Surgery ~ Current Problems in. Colonic Diverticular Disease

Transcription

1 Current Problems in Surgery ~ Volume 37 Number 7 July 2000 Colonic Diverticular Disease II Foreword In Brief Biographic InFormation Introduction Epidemiologic and Pathophysiologic Features and Natural History Incidence and Epidemiologic Features Etiologic Factors Pathophysiologic Features Natural History Uncomplicated Diverticulitis Diagnosis and Evaluation Medical Treatment Surgical Options Complicated Diverticular Disease Diverticular Hemorrhage Fistula Obstruction/Abscess Perforation Summary Curr Probl Surg, July

2 Special Problems Recurrent Diverticular Disease after Previous Resection Right-sided Diverticulitis Atypical Diverticulitis Diverticulitis in the Immunocompromised Patient Giant Colonic Diverticulum References Curr Probl Surg, July 2000

3 .gg, Foreword One of the more common maladies affecting Western society is colonic diverticulosis. The complications associated with this disease are myriad and include colonic perforation, diverticulitis and abdominal abscess formation, colonic hemorrhage, and colovesical fistula. For this issue of Current Problems in Surgery, Drs Young-Fadok, Roberts, Spencer, and Wolff of the Mayo Clinic, the Lahey Clinic, and the University of Minnesota have joined to write a monograph devoted to this topic. They provide a thorough review, beginning with the epidemiology, pathophysiology, and natural history of diverticulosis. Most of the manuscript is concerned with the management of patients with either uncomplicated or complicated diverticulitis. There is also a section addressing special problems associated with diverticulitis. This monograph is excellent and will serve especially well as a sole source reference for medical students, house officers, and practicing physicians who care for these patients. Samuel A. Wells, Jr, MD Editor in Chief Curr Probl Surg, July

4 gg, In Brief Colonic diverticulosis is common in industrialized nations, and the prevalence increases dramatically with increasing patient age. Diverticulosis is found in approximately 1% to 2% of patients who are less than 30 years of age, whereas diverticulosis is found in more than 40% of patients who are more than 60 years of age. Although symptoms will develop in 10% to 25% of patients with diverticulosis, few patients require hospitalization for septic complications. Although diverticula may occur throughout the colon, the most common site of involvement is the sigmoid colon, in as many as 95% of patients. Cecal involvement occurs in approximately 5% of patients. In the United States, patients with left-sided diverticulitis have an incidence of diverticula in the right colon that has varied from 7% to 30%. In the Far East, diverticular disease affects the fight colon more commonly than the left colon. Although diverticular disease has been termed a 20th century disease and in particular a "disease of Western civilization," our understanding of the pathophysiologic features of the disease has not improved appreciably in the last 25 years. Dietary fiber appears to play a significant role; the disease is rare in populations whose diet is high in fiber. Surprisingly, however, no data are available to suggest that a high-fiber diet decreases the risk of diverticulitis in patients with diverticulosis. Diverticular disease is thought to represent a motility disorder, wherein high intracolonic pressures in the sigmoid colon cause the process of segmentation and herniation of the bowel wall. Most patients (69%-83%) with acute sigmoid diverticulitis have left lower quadrant pain, fever, and leukocytosis. Pelvic and rectal examinations may reveal a mass. Urinary tract symptoms are consistent with a pelvic phlegmon, but pneumaturia or fecaluria may be found with a colovesical fistula. The differential diagnosis includes carcinoma, Crohn's disease, ulcerative colitis, ischemic colitis, irritable bowel syndrome, pelvic inflammatory disease, pyelonephritis, and appendicitis. Although a diagnosis of diverticulitis may be made by contrast enema examination ultrasonography or computed tomography (CT) scanning, CT scanning has had an increasing role in the diagnosis of abdominal pain. In the setting of diverticulitis, CT scanning has a potentially diagnostic and therapeutic role. Because diverticulitis is largely an extramural disease, CT scanning (which permits the evaluation of both the bowel 462 Curr Probl Surg, July 2000

5 wall and mesentery) has obvious appeal. CT findings consistent with diverticulitis include thickening of the bowel wall, streaky mesenteric fat, and associated abscess. Patients with mild abdominal tenderness, in the absence of systemic signs and symptoms, may be treated on an outpatient basis. A low-residue diet is advocated during the acute phase, and a broad-spectrum antibiotic is prescribed for 7 to 10 days. Patients with increasing abdominal tenderness, significant fever, or the inability to tolerate an oral diet are hospitalized. If the patient's condition improves, elective diagnostic evaluation is performed. For patients with more severe signs and symptoms, including significant pain or localized peritonitis in the absence of free perforation, hospitalization is indicated. The initial therapy consists of bowel rest, intravenous antibiotics, and intravenous fluids. Antibiotics should be chosen to cover Gram-negative aerobes and anaerobes (bowel flora). Meperidine is preferred for analgesia instead of morphine because the latter may increase the intracolonic pressure in the sigmoid colon. Improvement (as manifested by decreased tenderness, fever, and leukocytosis) is often seen within 48 hours. Persistent fever and leukocytosis suggest an unresolving phlegmon or abscess, and CT scanning may help to identify patients who may be candidates for percutaneous drainage. Patients who improve are discharged with instructions to follow a lowresidue diet and-are evaluated with either a combination of flexible sigmoidoscopy and contrast enema or colonoscopy. After the acute inflammatory process has resolved, a high-fiber diet is recommended. After a single attack of diverticulitis, long-term fiber supplementation may prevent recurrences in most patients who are observed for more than 5 years. After a single attack of diverticulitis, approximately 22% to 30% of patients will have a second attack. After a second well-documented attack of diverticulitis, most patients will have further symptoms from diverticular disease, and elective resection should be considered. Surgical intervention is mandatory for patients with complications of diverticulitis (eg, perforation, abscess, obstruction, and fistula) and is associated with high mortality and morbidity rates. Ideally, patients should undergo operation before complications ensue. Elective resection is advocated for patients who fulfill the following criteria: (1) 2 or more attacks of proven diverticulitis that is generally severe enough to require hospitalization and (2) an attack of diverticulitis that is associated with leakage of contrast material at the time of barium or water-soluble enema, with obstructive symptoms, or with an inability to differentiate between diverticulitis and cancer. Elective resection should be performed 6 to 8 weeks after Curr Probl Surg, July

6 an initial attack of diverticulitis. This enables the acute symptoms to subside and the inflammatory process to resolve. Waiting longer periods of time may increase the possibility of another attack of diverticulitis. Sigmoid resection may be approached by either an open technique or a laparoscopic technique. Although the inflammatory changes associated with diverticulitis may make a laparoscopic approach difficult, in 1 series of 164 patients, a laparoscopic approach was successful in 148 patients (90%). The transitional 3-stage procedure is rarely indicated in this day of advanced antibiotics, on-table lavage, ureteral stent placement, and CTguided drainage. Factors to consider in each patient include the degree of peritoneal contamination, the patient's overall clinical situation, and the condition of the bowel wall in the region of the intended anastomosis. Primary anastomosis may be contraindicated in patients who are hemodynamically unstable, immunocompromised, and malnourished. The Hartmann procedure, originally described by Hartmann in 1923 for the treatment of patients with carcinoma of the rectum, is the most commonly performed 2-stage procedure for the treatment of patients with diverticulitis. This procedure involves mobilization and resection of the sigmoid colon and either a stapled or sutured closure of the rectum. An alternative is to use the distal end as a mucous fistula. However, when total sigmoidectomy has been performed, a sufficient length of bowel is rarely present to permit construction of a tension-free mucous fistula. An alternative to the Hartman procedure (in favorable circumstances with a lack of significant contamination, a good blood supply to bowel ends, a lack of anastomotic tension, and a relatively empty colon) is resection with primary anastomosis with a proximal stoma. This may consist of an ileostomy or diverting colostomy. When a patient cannot undergo preoperative mechanical and antibiotic bowel preparation, on-table lavage may be considered with subsequent primary resection and anastomosis in selected patients. A patient with a discrete abscess will have continued fever, abdominal tenderness, leukocytosis, and often unresolved ileus on examination. Although a small pericolic abscess may resolve with antibiotic therapy, larger abscesses or distant abscesses (such as retroperitoneal or pelvic abscesses) often require surgical intervention or percutaneous drainage under ultrasonographic or CT guidance, When a discrete abscess is found by CT or ultrasound scanning, percutaneous drainage may permit stabilization of the patient's condition. As a result of the septic process, a singlestage sigmoid resection instead of a 2-stage procedure may be possible. The incidence of left-sided colonic obstruction associated with divertic- 464 Curr Probl Surg, July 2000

7 ular disease varies from 8% to 65%, with most series reporting an incidence of approximately 10%. Obstruction associated with diverticular disease is usually incomplete and resolves with bowel rest and nasogastric suction. For patients whose symptoms resolve, endoscopic or contrast studies or both are performed to confirm a diagnosis of diverticular obstruction and to exclude a diagnosis of cancer. Resection and primary anastomosis can then be performed after mechanical and antibiotic bowel preparation. In patients with unresolving obstruction, urgent operation is performed. Primary resection with end colostomy and Hartmann closure of the rectum may be performed. In selected patients, on-table colonic lavage and sigmoid resection with primary anastomosis can be performed safely. Fistulas associated with diverticulitis result from the perforation of localized pericolic abscesses and may involve adjacent structures, such as the bladder, uterus, vagina, fallopian tubes, ureter, small intestine, or abdominal wall. Fistulas have been reported in 10% to 24% of patients who have undergone resection for complicated diverticular disease. Colovesical fistulas are most common and comprise approximately 50% of all fistulas that are associated with diverticular disease. These fistulas are more common in men than in women because of the protective effect of the intervening uterus. Most patients have urinary tract signs and symptoms on examination. Pneumaturia and recurrent polymicrobial urinary tract infections are common manifestations. Bowel complaints are usually mild because the area has decompressed from the higher pressure colonic side into the bladder. CT scanning is the best imaging study to demonstrate a colovesical fistula. Treatment consists of sigmoid resection and simple closure of the fistulous connection with the bladder. As long as a diagnosis of cancer has been excluded as the cause of the fistula, the fistulous communication may be pinched off and oversewn. Formal bladder resection is unnecessary. A Foley catheter is left in place for several days after operation. Free perforation is the most morbid complication of acute diverticulitis and occurs in 4% to 15% of patients who undergo operation for complicated diverticular disease. Patients with this complication are extremely ill, and after resuscitation (consisting of broad-spectrum antibiotics and intravenous fluids), immediate operation is indicated. Sigmoid resection with proximal end stoma and Hartmann closure of the rectum is the most commonly performed procedure. An estimation is that 30% of patients with diverticulosis have lower gastrointestinal tract bleeding at some point, ranging in severity from an occasional guaiac-positive stool to massive lower gastrointestinal tract bleeding. This number is probably an overestimation because of the greater Curr Probl Surg, July

8 frequency of endoscopic examinations and because the number of guaiacpositive stools that are attributed to diverticular disease has often been found to be the result of vascular ectasia, polyps, or colorectal carcinoma. A patient with known diverticulosis, guaiac-positive stool, and no obvious anorectal source of bleeding should be evaluated by colonoscopy. Diverticular hemorrhage is associated with diverticulosis and not with the inflammatory changes of diverticulitis. For patients with brisk hemorrhage, efforts should be made to localize the precise site of the bleeding. Persistent hemorrhage is treated with resection of the involved colonic segment. In rare instances, if the site of bleeding is not localized and if the small bowel is excluded as the cause of bleeding, subtotal colectomy is performed. Recurrent diverticulitis develops in approximately 7% of patients who undergo sigmoid resection for diverticular disease, and ultimately approximately 3% of patients require further operation. The incidence of recurrence is often found to be significantly higher if the distal margin used in the anastomosis was sigmoid colon compared with proximal rectum. Therefore, to prevent recurrent diverticular disease, the entire sigmold colon should be removed and resected distally onto the rectum. The proximal margin of resection is less clearly defined, and in general, the surgeon should resect proximally to an area of soft pliable bowel. Excision of all proximal diverticula is not necessary, but the resection should be free of diverticula. Immunocompromised patients with diverticulitis (including those patients receiving steroid therapy), patients who have undergone organ transplantation, patients with cancer who are undergoing chemotherapy or radiotherapy, patients with diabetes, and patients with chronic alcoholism tend to have a more complicated course, with increased morbidity and mortality rates and higher rates of free perforation and the need for operation. This is presumably the result of the inability to wall off the disease process. Patients with polycystic kidney disease seem to have a significantly higher rate of complicated diverticulitis than other patients after renal transplantation, and it has therefore been suggested that an aggressive diagnostic evaluation is indicated in these patients, even for minor abdominal pain. Diverticular disease of the colon is rare in patients younger than 40 years of age and constitutes only 2% to 5% of the total number of patients evaluated in multiple large series. Diverticular disease in young patients has been considered to be more virulent and more likely to be associated with complications. Although a large number of young patients with acute diverticulitis 466 Curr Probl Surg, July 2000

9 require urgent or emergent laparotomy at the time of initial examination, the natural history of diverticular disease after a single episode of relatively mild diverticulitis in this group is less clearly defined. Such patients may recover fully and, with the institution of a high-fiber diet, may never have another bout of diverticulitis. However, because a young person will have a life expectancy of an additional 30 to 40 years, long-term follow-up studies are necessary. Therefore, diverticulitis in young patients may have a natural history similar to that of older patients, and a recommendation for operation after only 2 attacks of diverticulitis may be reasonable. Cecal diverticula consist of 2 types. The congenital variety, a true diverticulum, is usually solitary and contains all layers of the bowel wall. Acquired diverticula are usually multiple and are associated with diverticula elsewhere in the colon. Like sigmoid diverticula, they contain only mucosa and muscularis mucosa and therefore are false diverticula. Cecal diverticulitis is rare, with approximately 900 cases reported. At examination, patients with cecal diverticulitis may have a clinical picture identical to that of patients with acute appendicitis. Patients with cecal diverticulitis tend to be older than patients with appendicitis (average age, 40 years) and younger than patients with sigmoid diverticulitis. Radiographic signs include paracolic mass, calcified fecalith, and localized ileus. Improved diagnostic accuracy with CT scanning has been reported. At laparotomy, cecal diverticulitis may be indistinguishable from acute appendicitis. However, a striking inflammatory reaction in the mesentery of the ascending colon in the absence of similar change in the appendix is suggestive of the diagnosis. Treatment should be dictated by the intraoperative findings. If a solitary diverticulum is found with a well-circumscribed area projecting from the cecal wall, excision of the involved diverticulum and closure is adequate. In most cases, however, a significant inflammatory mass is found that involves the cecum and ascending colon, and fight colectomy is indicated. For multiple diverticula or a cecal phlegmon or when neoplastic disease cannot be excluded, fight colectomy and ileocolic anastomosis are indicated. Curr Probl Surg, July

10 . _. ~ ~ ~.~,_~.~k~c--~.,~41 ~ Tonia M. Young-Fadok, 9 BM, BCh, received her degrees from Oxford University. After 2 years of research at the Beth Israel Deaconess Hospital in Boston, she entered the general surgery residency at St Elizabeth's Medical Center in Boston. She then completed a colon and rectal surgery fellowship at the Mayo Clinic, plus an additional year of laparoscopic colorectal training. In 1997 she joined the faculty at the Mayo Clinic in the Division of Colon and Rectal Surgery and currently is Assistant Professor of Surgery at Mayo Medical School. In June 2000, she received a Master of Science in Epidemiology from the Harvard School of Public Health. Her research interests include the application of laparoscopic techniques to colorectal procedures and surgical outcomes research. Patricia L. Roberts, MD, / / ~. ~ J received her BA and MD degrees from the 6-year medical education program at Boston University. After completing her general surgical residency at Boston University, she completed a clinical and research fellowship in colon and rectal surgery at the Lahey Clinic. Since 1988 she has been a staff surgeon in the Department of Colon and Rectal Surgery at the Lahey Clinic. She is Assistant Clinical Professor of Surgery at Tufts University School of Medicine. Her interests include diverticular disease, inflammatory bowel disease, and clinical guideline and pathway development for colon and rectal surgery. ~'/L~,~z..~(f ~,._~- Z ~. / ~ Michael P. Spencer, MD, received his medical degree from Southern Illinois University. He completed a general surgery residency and research fellowship at the Mayo Clinic before completing a colon and rectal surgery fellowship at the University of Minnesota. In 1992 he joined the faculty of the University of Minnesota Division of Colon and Rectal Surgery and became a partner in Colon and Rectal Surgery Associates, Ltd, of Minnesota. His interests include fecal incontinence, placement of the artificial bowel sphincter, diverticular disease, and rectal cancer. 468 Curr Probl Surg, July 2000

11 ,,v.-,..,.~ ~. ~,t~,'~':'~ Bruce G. Wolff, M D, received his medical degree from Duke University. He began an anesthesia residency at Duke Medical Center before undertaking a residency in general surgery at The New York Hospital, Cornell Medical Center. After 2 years of military service, he completed his general surgery training in This was followed by a colon and rectal surgery residency at the Mayo Clinic, after which he became a consultant in colon and rectal surgery there. He is currently Professor of Surgery at Mayo Medical School. His interests include inflammatory bowel disease and colorectal neoplasia. Curr Probl Surg, July

12 Colonic Diverticular Disease ~ diverticulum (plural, diverticula) is a sac-like protrusion of mucosa through the muscular colonic wall. Diverticulosis indicates the presence of diverticula and generally denotes an absence of symptoms. Diverticulitis describes the presence of an inflammatory process associated with diverticula. Diverticular disease is a term that encompasses the spectrum of clinical manifestations of the presence of diverticula, including hemorrhage, inflammation (diverticulitis), or its complications (ie, obstruction, fistula, and perforation). Epidemiologic and Pathophysiologic Features and Natural History Incidence and Epidemiologic Features Incidence. Diverticular disease has increased in incidence since the beginning of this century, when it was an uncommon entity. Mayo and colleagues 1 first reported surgical resection for complicated diverticulitis in The prevalence has apparently increased from 5% to 10% in the 1920s 2 to between 35% and 50% in the late 1960s. 3 Unfortunately, there are no large recent population-based studies. There is a definite relationship to age, with a prevalence of less than 5% at 40 years of age, increasing to 30% by age 60 years, and up to 65% by age 85 years. 4'5 Estimates of the incidence of bleeding in diverticulosis suggest that bleeding is encountered in 15% of patients with diverticulosis. 6 In one third of these patients, or 5% of all patients with diverticulosis, the bleeding is massive. Colon carcinoma is the most common source of lower gastrointestinal bleeding, but diverticular bleeding is the most common cause of massive blood loss, being estimated to be the source of 30% to 50% of massive colonic bleeding. 7'8 With current methods of investigation, it is estimated that angiodysplasia accounts for another 20% to 30% of massive colonic bleeding 8 and is a more common cause of bleeding than diverticulosis in patients over the age of 65 years. 9,1~ Patients who have diverticular bleeding are often elderly (mean age, years) 7'8 and have comorbid conditions that contribute to the high morbidity and mortality rates (10%-20%) noted in early series. TM Epidemiologie Features. The effect of age appears to be moderated by gender. Early reports suggested a male preponderance, but more recent studies show either an equal distribution or a female preponderance. 5 This 470 Curr Probl Surg, July 2000

13 discrepancy is possibly explained by a large series from 1974 through 1983 that illustrated a gender distribution that varied according to age. 12 Overall, of these patients, 59.1% were women and 40.9% were men. In patients under 50 years of age, men predominated (35 men, 16 women). Men were less frequent in ages 50 to 70 years (77 men, 100 women); after 70 years of age, women predominated (30 men, 92 women). The overrepresentation of men has also been noted in acute diverticulitis in patients younger than 40 years of age. 13,14 Geographic location impacts on both the prevalence of diverticular disease and its anatomic distribution. Prevalence rates in "Westernized" nations vary from 5% to 45%, depending on the method of diagnosis and the age of the study population. 3,~5 Most diverticular disease in these countries is left-sided, with fight-sided diverticulitis occurring in only 1.5%. 16 This differs markedly from parts of Africa and Asia where the prevalence is less than 0.2% and is usually right-sided. 2,17 As Japan has adopted a more Western lifestyle, there has been an increase in diverticulosis, TM but it remains right-sided. 3 In Singapore, the incidence has risen to 20%, and fight-sided disease remains more common; 70% of cases are seen in patients who are less than 40 years old. 19 In Hong Kong up to 76% of diverticulosis affects the right colon2~ right-sided diverticulitis accounts for 17% of acute diverticulitis but is still rare, being encountered only once in every 180 cases of appendicitis? 1 Etiologic Factors Painter and Burkitt 4,22 postulated that low dietary fiber predisposes to the development of diverticular disease. Although this has remained controversial, 17'23'24 the Health Professionals Follow-Up Study, 25 of a cohort of over 47,000 men, has provided stronger evidence for the role of fiber. After an adjustment for age, energy-adjusted total fat intake, and physical activity was made, total dietary fiber intake was found to be inversely associated with the risk of symptomatic diverticular disease (ie, a diet low in dietary fiber increases the risk). Further evidence is provided by the finding that diverticular disease is less common in vegetarians than nonvegetarians. 26 Other dietary factors have been examined. A separate analysis in the Health Professionals Follow-Up Study 27 found no increased risk associated with smoking, caffeine, or alcohol. Other investigators, 28 however, have suggested that smoking may be an independent risk factor that predisposes the individual with diverticular disease to the development of complications. Certain common analgesic medications have also been implicated. The Health Professionals study 29 identified and followed more Curr Probl Surg, July

14 than 35,000 male health professionals who were initially free of diverticular disease; 310 cases were diagnosed over a 4-year period. After an adjustment was made for confounding factors, the consistent use of nonsteroidal anti-inflammatory drugs and acetaminophen was positively associated with the risk of symptomatic diverticular disease, particularly bleeding. Much smaller series have noted an association of obesity in men less than 40 years old with acute diverticulitis. This would agree with observations that the combination of a high intake of total fat or red meat and a diet low in total dietary fiber either augments the risk of symptomatic diverticular disease over the risk associated with a low fiber intake or is a marker for higher risk. 26 Pathophysiologic Features Pathologic Features. A colonic diverticulum is a "false" or pulsion diverticulum. Hence, it does not contain all layers of the wall as a true (congenital) diverticulum does. The mucosa and submucosa herniate through the muscle layer and are covered only by serosa. Diverticula develop at 4 well-defined points around the circumference of the colon, where the vasa recta penetrate the circular muscle layer. 3~ These vessels enter the wall on either side of the mesenteric taenia and on the mesenteric border of the 2 antimesenteric taeniae (Fig 1). Diverticula do not develop in the rectum, presumably because of the coalescence of the tenia into the longitudinal muscle layer, which marks the junction between the sigmoid colon and the rectum. Diverticula are not distributed equally throughout the colon. Ninety-five percent of patients have diverticula in the sigmoid colon, although 35% of patients also have more proximal disease. In 65% of patients, diverticula are limited to the sigmoid colon. In 24% of patients, diverticula involve the sigmoid and other segments of the colon. Diverticula occur throughout the colon in 7% of patients, and only 4% of patients exhibit diverticula limited to a segment proximal to the sigmoid. 31 The location of diverticular disease requiring operation is similar, with 95% of all operative cases involving the sigmoid. 12 Pathophysiologie Features of Divertieulosis. Areas where the circular muscle is traversed, where the vasa recta penetrate the bowel wall, are considered to be points of weakness. These are the points at which diverticula develop and have been demonstrated angiographically. 32 Most patients with sigmoid diverticula exhibit myochosis, a set of findings that includes thickening of the circular muscle layer, shortening of the taeniae, and luminal narrowing. There is no hypertrophy or hyperplasia of the bowel wall, but there is increased elastin deposition in the 472 Curr Probl Surg, July 2000

15 Mesenterlc tenia t recta ' -Anti-mesenterlc Fig 1. Cross-section of the sigmoid colon. The illustration indicates the points of penetration of the vasa recta around the bowel circumference. Insets, The development of a diverticulum at 1 such point of weakness. (From Young-Fadok TM, Pemberton JH. Colonic diverticular disease: epidemiology and pathophysiology. In: Rose BD, editor. UpToDate in medicine [CD-ROM]. Wellesley, MA: UpToDate; With permission.) tenia. 33 Structural changes in the collagen of the bowel affected by diverticulosis are similar to those changes that occur with aging but are greater in magnitude. 34 These changes may result in decreased resistance of the wall to intraluminal pressure. Structural changes in the wall may also be responsible for the occurrence of diverticula at an early age in connective tissue disorders such as Ehlers-Danlos and Marfan's syndromes. Diverticula are believed to develop as a result of elevated intraluminal pressures. This proposal became more plausible after a demonstration of the existence of segmentation of the colon. 35 Segmentation describes the strong muscular contractions of the colonic wall that serve to propel luminal contents or to halt the passage of material. If 2 such contractions occur relatively close to each other and form an enclosed space, the pressure in the intervening segment of colon may exceed 90 mm Hg (Fig 2). That this is most common in the sigmoid colon is potentially explained by the law of Laplace, which states that pressure (P) is directly proportional to wall tension (T) and inversely proportional to the bowel radius (R; ie, P -- kt/r [where k is a conversion factor]). It has been suggested that, because the Curr Probl Surg, July

16 \ Fig :2. The concept of Painter and Burki~ of segmentation that causes the formation of pulsion diverticula. (From Pemberton JH, Armstrong DN, Dietzen CD. Diverticulitis. In: Yamada T, editor. Textbook of gastroenterology. 2nd ed. Vol 2. Philadelphia: Lippincott; p With permission.) sigmoid colon is the segment of the colon that has the smallest diameter, it will also be the site of the highest pressure. This would not be true under normal circumstances because the colon is, in effect, a long tube and the pressure should be the same throughout the colon. However, the process of segmentation separates the lumen into a series of chambers, and these pressure changes appear to be most exaggerated in the sigmoid colon. This allows isolated increases of intraluminal pressure that are thought to predispose to herniation of mucosa through the weak points noted earlier. Pathophysiologic Features of Diverticulitis. The term diverticulitis represents a spectrum of inflammatory changes that range from localized subclinical inflammation to generalized peritonitis with free perforation. The underlying cause is believed to be perforation of a diverticulum, either microscopic or macroscopic. An early belief that obstruction of the diverticular lumen (eg, by a fecalith ) was responsible for increased diverticular pressure and subsequent perforation (similar to the pathogenesis of appendicitis) is now thought to be a rare event. 17 Increased intraluminal pressure or inspissated food particles may erode the diverticular wall; inflammation and focal necrosis ensue, and perforation results. If the perforation is small and the patient is immunocompetent, inflammation may 474 Curr Probl Surg, July 2000

17 be mild, and the perforation is walled off by pericolic fat and mesentery. A localized abscess may form. If adjacent organs are involved in this containment, a fistula or obstruction may develop. Poor containment results in free perforation and peritonitis. Pathophysiologic Features of Diverticular Bleeding. Consideration of the manner in which diverticula develop helps to explain the mechanism of diverticular bleeding. As a diverticulum herniates, the penetrating vessel that is responsible for the wall weakness at that point becomes draped over the dome of the diverticulum and is separated from the bowel lumen only by mucosa. Over time the artery is exposed to injury along the aspect of the vessel that faces the lumen. Microangiographic studies demonstrate a characteristic angioarchitecture of colonic diverticula. 32 There is asymmetric rupture of the vas rectum (the blood vessel draped over the diverticulum) toward the lumen of the diverticulum at its dome or antimesenteric margin. This is associated with eccentric thickening of the intima of the vessel, with thinning of the media near the bleeding point. There is also a general absence of diverticulitis. These changes are histologically identical to those produced by experimental forms of injury. This has led to the conclusion that injurious factors within the colonic lumen produce asymmetric damage to the luminal aspect of the underlying vas rectum, resulting in segmental weakness of the artery and a predisposition to rupture into the lumen. The anatomic relationship between diverticula and vasa recta is similar in both the fight and left colon. However, the right colon is the source of diverticular hemorrhage in 48% to 90% of patients, 7,3~ despite the fact that approximately 75% of all diverticula are in the left colon; when fightsided diverticula occur, they are usually associated with left-sided diverticula. 17 One possible explanation for the increased frequency of bleeding from the right colon is that fight-sided diverticula have wider necks and domes, potentially exposing the vasa recta over a greater length to injury. 3~ Other authorities suggest that the phenomenon may be explained by the thinner wall of the fight colon. 6 Natural History Understanding of the natural history of diverticular disease is important in the determination of which patients are the most appropriate candidates for surgical intervention. Diverticulosis. Most patients with diverticulosis appear to remain asymptomatic. Approximately 70% of patients remain asymptomatic; diverticulitis develops in 15% to 25% of patients, and 5% to 15% exhibit some form of diverticular bleeding. Because most patients remain asymp- Curr Probl Surg, July

18 First Episode Second Episode Mortality 1.3-5% Mortality 5-10% Morbidity 25% Morbidity 50-60% Asyrnptornatic k ~ 30-40% 85%.I CONSERVAa'IVE. A~ocramps " ~ ' 30%~ SECOND ~ AsymP0t~ Fig 3. Colonic diverticular disease: natural history, clinical features, and diagnosis. (From Young-Fadok TM, Pemberton JH. Colonic diverticular disease: epidemiology and pathophysiology. In: Rose BD, editor. UpToDate in medicine [CD-ROM]. WelLesley, MA: UpToDate; With permission.) tomatic, the mere presence of diverticula does not indicate the need for intervention. Some patients may benefit from a high-fiber diet. Diverticulitis. Diverticulitis represents a spectrum of disease that ranges from mild peridiverticular inflammation (that can be treated on an outpatient basis) to perforated diverticulitis with fecal peritonitis, sepsis, and death. This spectrum can be divided broadly into 2 groups: simple and complicated diverticulitis (Fig 3). Simple diverticulitis (approximately 75% of this group) refers to those diseases that respond to medical therapy. Complicated diverticulitis describes the development of perforation, obstruction, abscess, or fistula, which arise in approximately 25% of patients. Most of those patients with complicated disease will require operation, either acutely or on an elective basis. After the first episode of diverticulitis, 20% to 29% 37,38 of patients require surgical intervention. Most have complicated diverticulitis. Emergent or urgent indications for operation during the acute phase are free perforation with generalized peritonitis, obstruction, clinical deterioration or failure to improve with conservative management, and abscess not amenable to percutaneous drainage. Indications for elective surgical intervention are recurrent or intractable symptoms, persistent mass, inability to exclude carcinoma, obstruction, presence of a fistula, and previous percutaneous abscess drainage (PAD). With the first episode of diverticulitis, 15% to 25% of patients exhibit complications that require operative intervention, and 75% to 85% of patients respond to conservative therapy? 7 The overall mortality rate is 1% to 5%. 37,39 Long-term follow-up (median, 48 months) reveals a read- 476 Curr Probl Surg, July 2000

19 mission rate of 2% per patient year of follow-up. 37 Between 30% and 40% of patients remain asymptomatic; another 30% to 40% of patients experience episodic abdominal cramps or discomfort without frank diverticulitis, and approximately 20% to 30% of patients proceed to a second episode of diverticulitis. 39,4~ Up to 60% of this latter group experience complications, and the mortality rate is doubled. In addition, only 10% of patients subsequently remain asymptomatic after recovering from this second attack. 5,6 This underscores the importance of an understanding of the natural history and of an attempt to identify those patients at higher risk of experiencing further episodes. Therefore, for most patients who experience second uncomplicated episodes of diverticulitis that require hospitalization, elective resection is usually recommended. Patients who are treated operatively are generally considered to be cured even if diverticula are left in the proximal colon. Progression of diverticulosis in the remaining colon occurs in only 15% of patients, 41 with a need for additional surgery in only 2% to 11% of patients However, up to 27% of patients describe abdominal pain after operation in the same location. These persistent symptoms may be explained by coexistent irritable bowel syndrome rather than by recurrent diverticulitis, because there is an excess representation of female patients in this group. Diverticulitis in Young Patients. Certain subsets of patients appear to have a higher risk of complications either concomitant with or subsequent to a first episode of diverticulitis. The management of complicated diverticulitis with free perforation, failure of resolution with medical management, abscess, stricture, or fistula involves surgical intervention and is independent of the age of the patient. However, there is controversy about the management of young patients when the first episode of diverticulitis has resolved with medical therapy. The current "standard of therapy" has been to recommend elective resection in young patients after resolution of the first episode. This recommendation is based on 2 premises. First, these young patients experience a more virulent form of the disease and are more likely to have complications (eg, perforation, fistulas, and obstruction) and to require operation for the first episode. The second premise is that patients who respond to medical management are more likely to have recurrent episodes of diverticulitis and ultimately require surgical intervention: A review of the literature, however, Suggests that the clinical situation is not so well defined. The natural history of diverticulitis in the younger patient is clouded by the relative rarity of the diagnosis, which precludes large series. Patients younger than 40 years of age comprise 12% to 29% Curr Probl Surg, July

20 of a large series. 13'14'38'44'45 The percentage of these patients who require surgical intervention varies widely as does the apparent high rate of misdiagnosis. A closer look at reported series explains some of these discrepancies. Certain features of this patient group are common to most reported series. Unlike the overall population with diverticulitis, where there is a modest female predominance, there is a consistent male dominance in patients younger than 40 years of age (range, 2:1-4:1). 13'14'3s'45 Being young, these patients have few comorbid conditions, with the exception of obesity, which is noted in up to 84% to 96%. 14'45 Diverticulosis is classically confined to the sigmoid with or without the descending colon. The suggestion that diverticulitis is more virulent in young patients arises from several series that have shown that a higher percentage of these patients require operative intervention. However, the incidence of surgical intervention varies widely from 23% to 76%. 45'46 For purposes of comparison, large studies of all patients with diverticulitis indicate an overall incidence of operative intervention of 27% to 33%. 5'12 Support for the more virulent theory comes from studies of young patients alone that demonstrated operative rates of 48% to 88%. 14'44'45 Other series of young patients have found disagreement with this statement and demonstrated operative rates during the first admission of 15% to 41%. 13'38 Many younger patients undergo urgent operation because of an incorrect preoperative diagnosis47; this is supported even in the more recent literature, in which series with high missed diagnosis or incorrect diagnosis rates of 41% to 50% 14'45 are associated with higher operative rates. One series of 63 patients under 45 years of age found that 65% of the patients were successfully treated medically. Of the 22 patients (35%) who underwent emergent operation, 12 patients were misdiagnosed preoperatively (ie, only 10/63 patients [16%] actually required urgent operation). 48 In 1 study in which preoperative computed tomography (CT) scans or contrast studies were used extensively, the operative rate in patients less than 40 years of age was 15% compared with 33% in older patients. 38 However, this same study also supports the "more virulent" theory because younger patients had more severe diverticulitis by CT scan than older patients and had an increased incidence of poor outcomes (eg, persistent inflammation, residual abscess, fistula, and colonic stenosis) that ultimately required operation. 38 Other investigators have noted this trend in the natural history towards recurrence of symptoms. A report of 77 patients younger than 50 years of age showed that 23% of patients required operation at examination for complications of peritonitis, abscess, bowel obstruction, and fistula. One 478 Curr Probl Surg, July 2000

21 fourth of the whole group and two thirds of those patients undergoing operation had previously been hospitalized with a complication of diverticular disease. 46 The recurrent nature of the disease in patients younger than 40 years of age was reported in medically treated patients who had more emergency room visits and complications than those patients whose condition was managed surgically. 49 The authors recommended resection for the first episode of diverticulitis in patients younger than 40 years of age. However, whereas some studies have reported readmission rates of up to 55% 5o and subsequent operative rates of 20% to 41%, 47,5~ other studies have reported no subsequent operation after 4 years. 52 As a result, the outcome after successful medical management is also disputed. One way to summarize these conflicting data is to consider the overall total operative rate, either during the first admission or subsequently. 53 This appears to be in the range of 50%, with many series either suggesting a high initial operative rate at the first presentation ~4'44'45 or a lower rate on first admission of 15% to 25%, but with a poor outcome in up to 29% 38 of patients at first admission or subsequent operation in 32% of patients. 51 These data are relatively consistent when examined in this manner, but different authors have different interpretations. Some have concluded that after medical therapy a risk of subsequent operation of 32% to 41% in patients followed for 5 to 9 years does not merit elective operation. 51 Other authors would disagree with this approach and recommend elective resection on the basis of the same data. 5~ In conclusion, it is unclear whether young patients experience a more virulent form of diverticulitis. The diagnosis may not be considered in younger patients, therefore leading to higher operative rates. The percentage of patients who require operation may be lower when CT scans are readily used. There is also evidence that suggests an ultimate operative rate of approximately 50%. As the initial diagnosis improves with more widespread use of CT scanning, although the requirement for operation on the first admission may fall, a larger proportion of those patients who are treated with antibiotics may ultimately require resection. Once the patient is advised of the possible risks, the issue becomes one of patient evaluation of risks and lifestyle concerns. In a patient with no significant comorbid conditions, elective operation after a single episode remains a reasonable recommendation. Others with the same risk might equally be justified in following a course of observation. Immunosuppressed Patients. Immunosuppression is associated with an increased incidence of perforated diverticulitis. Such patients obviously include those patients who receive chemotherapy or long-term corticosteroid therapy, but the phenomenon is also apparent in patients with dia- Curr Probl Surg, July

22 betes and patients with renal failure. Such patients may have minimal symptoms or signs even in the presence of frank peritonitis, and the diagnosis is frequently delayed. Medical therapy of acute diverticulitis is successful in 75% of normal patients but is necessary in almost all patients who are immunocompromised. 54 Early surgical intervention should be considered in these patients. Diverticular Fistula. Diverticular fistulas account for up to 20% of surgically treated cases of diverticular disease. 55 In 90% of all patients with diverticulitis, the inflammation involves the sigmoid colon, and fistulization most commonly arises from this segment. Colovesical fistulas account for 65% of diverticular fistulas, with colovaginal fistulas next in frequency (25%), followed by coloenteric and colouterine fistulas. 55 However, a fistula can form to whichever organ the inflammatory process tracks and has been described in many unexpected sites. Colovesical fistulas are the most common of all diverticular fistulas, and conversely diverticulitis is the most common cause of colovesical fistula, accounting for 40% to 89% of colovesical fistulas. 56 Although diverticulitis occurs with a slight female predominance, colovesical fistulas as the result of diverticulitis occur 2 to 4 times more often in men, with male patients comprising 66% to 78% in some series. 55,57 That the uterus protects the bladder from the inflamed sigmoid is supported by the observation that 50% to 68% of women with a colovesical fistula and 83% with colovaginal fistulas have had a previous hysterectomy. 55,56'58 Diverticular Bleeding. Only 15% of all patients with diverticulosis have any form of bleeding. Approximately 70% to 80% of patients with hemorrhage stop bleeding spontaneously, but the risk of rebleeding is 14% to 25%. 7,59 However, this risk of subsequent bleeding increases to 50% in patients who experience a second episode of bleeding? 9 Uncomplicated Diverticulitis Diagnosis and Evaluation Most patients (69%-83%) with acute sigmoid diverticulitis have left lower quadrant pain, fever, and leukocytosis. Pelvic and rectal examinations may reveal a mass. Urinary tract symptoms are consistent with a pelvic phlegmon, but pneumaturia or fecaluria may be present with a colovesical fistula. The differential diagnosis includes carcinoma, Crohn's disease, ulcerative colitis, ischemic colitis, irritable bowel syndrome, pelvic inflammatory disease, pyelonephritis, and appendicitis. It has been suggested that the diagnosis can be made on the basis of clinical criteria; when the clinical picture is clear, no other tests are needed to 480 Curr Probl Surg, July 2000

23 Fig 4. A long stricture in a patient with long-standing diverticular disease. Endoscopic examination should be performed to exclude a diagnosis of cancer. make the diagnosis. 6~ However, by relying on clinical parameters alone, the diagnosis may be incorrect in up to one third of patients. 61,62 In the patient who is hospitalized because of a diagnosis of diverticulitis, we prefer to obtain objective confirmatory radiographic evidence of a diagnosis of diverticulitis. Although a diagnosis of diverticulitis may be established by contrast enema examination (Figs 4-6), ultrasonography, or CT scanning, CT scanning has had an increasing role in the diagnosis of abdominal pain. In the setting of diverticulitis, CT scanning has a potentially diagnostic and therapeutic role. Because diverticulitis is largely an extramural disease, CT scanning, which permits the evaluation of both the bowel wall and mesentery, has obvious appeal. CT findings consistent with diverticulitis include thickening of the bowel wall, streaky mesenteric fat, and associated abscess (Fig 7). In a series of 42 CT examinations in patients with diverticular disease, 63 the most common findings were inflammation of the pericolic fat (98%), diverticula (84%), thickening of the bowel wall (70%), pericolic abscess (35%), peritonitis (16%), fistula (14%), colonic obstruction (12%), and intramural sinus tracts (9%). CT scanning is the best imaging technique for demonstrating colovesical fistula in which the presence of air in the bladder Curr Probl Surg, July

24 Fig 5. Long intramural fistula (arrow) is consistent with a diagnosis of diverticulitis. Intramural fistulas may also be seen in Crohn's disease. Fig 6. Barium enema examination (lateral view) shows a large colovaginal fistula (arrow). 482 Curr Probl Surg, July 2000

25 Fig 7. A, CT scan shows a large abscess (arrow) filled with contrast material. The patient subsequently underwent percutaneous drainage and then single-stage sigmoid resection 6 weeks later. B, Complex pelvic abscess from diverticulitis (arrow). in the absence of previous instrumentation is diagnostic of a fistula (Fig 8). In a series of 23 patients who underwent CT scanning, 64 air was found in the bladders of 20 patients. Localized thickening of the bladder or the colon in the region of the fistula may also be present. Some studies 65'66 have shown in addition that the use of CT scanning for patients with acute diverticulitis enabled a more accurate diagnosis, identified complications of the disease earlier, and possibly led to decreased hospital costs. Curr Probl Surg, July

26 Fig 8. Air in the bladder (arrow) on CT scan in a patient with a colovesical fistula. Ultrasonography may reveal a thickened colonic wall or cystic masses with echogenic densities consistent with abscess. 67 A prospective study of 130 consecutive patients with abdominal complaints evaluated by ultrasonography 68 found ultrasonographic signs of diverticulitis in 96% of patients. Ultrasonography, however, is limited because it is operator dependent. In addition, abdominal distention, which is frequently present in patients with diverticulitis from either associated ileus or obstruction, may limit its utility. In the acute setting, a contrast enema should be performed if the diagnosis is equivocal or unclear, on the basis of the CT scan. In a patient with colonic obstruction, the contrast enema examination can distinguish whether the obstruction is from diverticular disease or cancer. Gastrografin is hyperosmolar and may sometimes assist in relieving a partial obstruction. Endoscopic procedures (either proctosigmoidoscopy or flexible sigmoidoscopy) are relatively contraindicated in the acute setting because insuffiation of air may convert a sealed perforation into a free perforation. In the presence of acute diverticulitis, limited sigmoidoscopy may be performed to exclude another diagnosis, such as inflammatory bowel disease. After a patient has recovered from an episode of diverticulitis, endoscopic examination of the sigmoid colon may be helpful to distinguish diverticular disease from carcinoma, particularly in the patient who is found to have a stricture. 484 Curr Probl Surg, July 2000

27 Medical Treatment Patients with mild abdominal tenderness in the absence of systemic signs and symptoms may be treated on an outpatient basis. A low-residue diet is advocated during the acute phase, and a broad-spectrum antibiotic is prescribed for 7 to 10 days. Patients with increasing abdominal tenderness, significant fever, or an inability to tolerate an oral diet are hospitalized. If the patient's condition improves, elective diagnostic evaluation is performed. For patients with more severe signs and symptoms (including significant pain or localized peritonitis in the absence of free perforation), hospitalization is indicated. Initial therapy consists of bowel rest, intravenous antibiotics, and intravenous fluids. Antibiotics should be chosen to cover Gram-negative aerobes and anaerobes (bowel flora). Meperidine is preferred for analgesia instead of morphine because the latter may increase intracolonic pressure in the sigmoid colon. Improvement (as manifested by decreased tenderness, fever, and leukocytosis) is often seen within 48 hours. Persistent fever and leukocytosis suggest an unresolving phlegmon or abscess, and a CT scan may help to identify patients who may be candidates for percutaneous drainage. Patients who improve are discharged with instructions to follow a lowresidue diet and are evaluated with either a combination of flexible sigmoidoscopy and contrast enema or colonoscopy. 6~ After the acute inflammatory process has resolved, a high-fiber diet is recommended. After a single episode of diverticulitis, long,term fiber supplementation may prevent recurrences in most patients who are observed for more than 5 years. 69,7~ After a single episode of diverticulitis, approximately 22% to 30% 31'4~ of patients will have a second episode. After a second well-documented episode of diverticulitis, most patients will have further symptoms from diverticular disease, and elective resection should be considered. Surgical Options Elective Procedures Sigmoid Resection. Surgical intervention is mandatory for patients with complications of diverticulitis (including perforation, abscess, obstruction, and fistula) and is associated with high mortality and morbidity rates. Ideally, patients should undergo operation before complications ensue. Elective resection is advocated for patients who fulfill the following criteria: (1) 2 or more episodes of proven diverticulitis generally severe enough to require hospitalization and (2) an episode of diverticuli- Curr Probl Surg, July

28 tis associated with leakage of contrast material at the time of barium or water-soluble enema, obstructive symptoms, or an inability to differentiate between diverticulitis and cancer. Elective resection should be performed 6 to 8 weeks after an initial episode of diverticulitis. This enables the acute symptoms to subside and the inflammatory process to resolve. Waiting longer periods of time may increase the possibility of another episode of diverticulitis. Before operation, the patient is prepared with a mechanical and antibiotic bowel preparation. Even after a period of 6 to 8 weeks after an episode of diverticulitis, a phlegmon may still be present, and dissection and mobilization of the left colon may be difficult. Urinary catheters are not generally used on a routine basis but may be helpful in some patients. Although they do not prevent ureteral injury, they may permit prompt recognition and repair of ureteral injuries. The incidence of ureteral injury in a series of 198 patients who underwent colonic resection was 2%. 71 A technique that may be helpful in mobilization includes "proximal-to-distal" resection in which the colon is divided proximal to the phlegmon with a linear stapler, and the colon is dissected proximal-to-distal rather than performing a lateral-to-medial dissection. 72 The proximal margin of resection is soft pliable bowel, and distally, the margin of resection is the proximal rectum. This is easily identified as the area in which the taeniae coalesce. Sigmoid resection may be approached by either an open technique or a laparoscopic technique. Laparoscopic mobilization may be performed with a subsequent intracorporeal double-stapled anastomosis. In a series of 25 patients who underwent laparoscopic resection for diverticular disease compared with 17 patients who underwent open resection for diverticular disease, 73 patients who underwent laparoscopic operation had a faster recovery and shorter hospital stay. The cost in this group was higher because of the higher cost of operating room usage time. Although the inflammatory changes associated with diverticulitis may make a laparoscopic approach difficult, in one series of 164 patients, 74 a laparoscopic approach was successful in 148 patients (90%). Hand-assisted laparoscopic techniques, whereby a hand may be placed through a small incision into the abdomen, thereby permitting the surgeon to have tactile sensation, may further increase the feasibility of laparoscopic operation for diverticular disease. 75 Surgery for Acute Diverticulitis Transverse Colostomy and Drainage. Lockhart-Mummery 76 and Smithwick 77 advocated staged operation for the treatment of patients with complicated diverticular disease. An initial proximal colostomy was fol- 486 Curr Probl Surg, July 2000

29 lowed by resection of the diseased segment and later closure of the colostomy. Smithwick 77 reported a mortality rate of 5% and a morbidity rate of 12% in a series of patients treated with staged operation. Subsequent reports, however, revealed much higher mortality and morbidity rates. Greif and colleagues 78 reviewed the records of more than 1300 patients who underwent operation for perforated sigmoid diverticulitis. The combined mortality rate for patients undergoing initial colostomy and drainage was 29% compared with 12% in patients who underwent primary resection. An additional review 79 of emergency operations for perforated diverticulitis found a mortality rate of 25% in patients treated without resection versus 11% in patients treated with resection. Threestage procedures have virtually no role in the management of complicated diverticular disease. Two-stage Procedures versus Primary Anastomosis. After sigmoid resection, the decision of whether to perform a primary anastomosis or to perform fecal diversion should be made. In most patients with pericolic abscess or pelvic abscess who have tolerated bowel preparation before operation, primary anastomosis may be performed. Most patients with purulent peritonitis and patients with fecal peritonitis require proximal fecal diversion. Factors to consider in each patient include the degree of peritoneal contamination, the patient's overall clinical situation, and the condition of the bowel wall in the region of the intended anastomosis. Primary anastomosis is contraindicated in patients who are hemodynamically unstable, immunocompromised, and malnourished. Selected patients who are hemodynamically stable and in whom there is minimal peritoneal contamination may undergo on-table lavage and primary anastomosis. Hartmann Procedure. The Hartmann procedure, originally described by Hartmann 8~ in 1923 for the treatment of patients with carcinoma of the rectum, is the most commonly performed 2-stage procedure for the treatment of patients with diverticulitis. The procedure involves mobilization and resection of the sigmoid colon and either a stapled or sutured closure of the rectum. Although the sigmoid colon is acutely inflamed and edematous, mobilization is almost always possible with the use of blunt finger dissection. Dissection from the proximal colon, proceeding in a caudad direction, facilitates the procedure. In diverticulitis, the proximal rectum is not involved, and this area serves as the distal margin of resection. An alternative is to use the distal end as a mucous fistula. However, when total sigmoidectomy has been performed, a sufficient length of bowel is rarely present to permit construction of a tension-free mucous fistula. Leaving inflamed distal sigmoid colon to achieve the cre- Curr Probl Surg, July

30 A CLINIC [O 199e Fig 9. To obviate the difficulty with subsequent reversal of a Hartmann procedure, primary resection and anastomosis (A) with proximal fecal diversion (B) may be performed. Colostomy closure (r is performed 3 months later. (Reprinted by permission of Lahey Clinic, Burlington, Mass.) ation of a mucous fistula also creates a potential source of persistent diverticulitis. After Hartmann resection, there is not universal agreement regarding the timing of closure of the colostomy. 81,82 Many patients may adapt to their stoma and elect to have no further surgery. Although a waiting period of at least 3 months is usually advocated, this should be individualized. Certainly, some patients may not have recovered sufficiently physically from the first procedure in this time, and an additional waiting period is indicated. Resection with Primary Anastomosis and Proximal Stoma. Although the Hartmann procedure successfully removes the septic focus of sigmoid colon, reversal of the colostomy may be difficult because of adhesions and difficulty with identification and mobilization of the rectal stump. In one series of 27 patients who underwent the Hartmann procedure, 83 closure of the colostomy was associated with a considerable length of stay and morbidity and left one third of patients with a permanent stoma. One way to obviate these potential difficulties is to perform a resection with primary anastomosis and proximal stoma at the time of the original operation (Fig 9). 84,85 The proximal diversion may consist of either a diverting colostomy or ileostomy. Single-stage Procedure with On-table Lavage. When a patient cannot undergo preoperative mechanical and antibiotic bowel preparation, ontable lavage may be considered with subsequent primary resection and 488 Curr Probl Surg, July 2000

31 anastomosis in selected patients. On-table lavage can be considered in patients with large-bowel obstruction as the result of diverticular disease and in patients with pericolic and, in selected patients, with pelvic abscesses who cannot be prepared before operation. Patients whose condition is hemodynamically unstable, who have significant purulent or fecal contaminations, are malnourished, or are immunosuppressed are not candidates for on-table lavage. On-table lavage is performed after standard mobilization of the sigmoid colon. Mobilization of the splenic and often the hepatic flexure is helpful. The lumen proximal to the area of diverticulitis is occluded with tape, and corrugated plastic tubing is inserted and secured with the distal end passed off the field into a disposable cannister. The bowel is cannulated proximally with a Foley catheter through either the appendix or, if the appendix has been removed, through the terminal ileum or cecum. Lavage is performed with warm saline solution through the Foley catheter until the returns are clear. Resection and anastomosis are then performed in the standard fashion. On-table lavage generally adds 30 to 45 minutes to the operative procedure. In 33 of 62 patients who underwent nonelective operation for diverticular disease, 1 anastomotic complication occurred, s6 According to the Hinchey classification, 18 patients had stage I disease, l0 patients had stage II disease, and 5 patients had stage III disease. Thus, on-table lavage can be accomplished with acceptable morbidity and mortality rates in selected patients. Complicated Oiverticular Disease The optimum management of complicated diverticular disease remains controversial and reflects in part uncertainty about the precise cause and natural history of diverticular disease itself. Because technical advances in medical and surgical care have enhanced our ability to stabilize patients nonoperatively and convert emergency surgical interventions into elective procedures, we have reduced the morbidity and mortality rates associated with acute diverticulitis. Diverticular disease is prevalent in aging Western populations, with estimates ranging from 35% to 50% in the general population. 3,87 The actual incidence of symptomatic inflammation leading to hospitalization is unknown, but it is estimated at 1% to 2%. Of patients hospitalized for symptomatic diverticular disease, 10% to 20% will eventually require operation. The indications and frequency of complications necessitating surgical intervention vary depending on the patient population studied. The findings of one such review compiled over 20 years at the Curt Probl Surg, July

32 TABLE 1. Indications for operation Primary complications Sepsis Fistula Obstruction Hemorrhage Recurrent attacks Persistent mass Symptomatic stricture Persistent urinary symptoms Rapid progression of symptoms Relative youth Inability to exclude carcinoma Modified from Rodkey GV, Welch CE. Changing patterns in the surgical treatment of diverticular disease. Ann Surg 1984;200: With permission. Massachusetts General Hospital are listed in Table 1. The focus of this review is to provide some historic background and a practical approach to several commonly encountered complications such as bleeding, fistula and abscess, and perforation associated with diverticular disease. Diverticular Hemorrhage Bleeding can be expected to occur in 15% of patients with diverticulosis, making diverticular disease one of the most common causes of acute lower gastrointestinal bleeding in adults. Advances in localization techniques with angiography and emergent colonoscopy have implicated angiodysplastic lesions with increasing frequency as a common cause of lower gastrointestinal bleeding, particularly in the geriatric population. Diverticular disease, however, accounts for massive rectal bleeding more often than any other source in most series. Despite improved diagnostic capabilities, 30% to 40% of all patients with lower gastrointestinal hemorrhage will fail to have a bleeding source accurately determined. Because most patients with diverticular hemorrhage will stop bleeding spontaneously (often before examination at the hospital), it is not surprising that the site of hemorrhage is not identified. The risk of rebleeding after the first hemorrhage is approximately 30% but increases to 50% after the second episode of bleeding. Right-sided diverticula are thought to have a greater risk of hemorrhage and rebleeding overall. 77 Diverticula develop adjacent to blood vessels as they penetrate the circular muscle layer of the bowel wall. The vasa recta at the neck of the diverticula are subject to degenerative and traumatic forces weakening the arterial wall and predisposing it to rupture. The pathologic finding of intimal damage and subsequent eccentric intimal thickening with eventual 490 Curr Probl Surg, July 2000

33 thinning of the underlying media have been well documented. It should be noted that diverticular hemorrhage usually occurs in the absence of acute or chronic inflammation. For most patients, the initial diverticular hemorrhage will be a self-limited episode with minor to moderate bleeding. Yet massive, exsanguinating hemorrhage can occur in up to one third of patients. The physical examination is usually unremarkable with no history of antecedent problems. A careful history, however, can often detect a previous episode of bleeding that has significant implications regarding recurrent hemorrhage. The management of lower gastrointestinal bleeding must be guided by the patient's overall clinical situation. Because most of these patients are elderly and frequently have comorbid conditions, it is not surprising that the morbidity and mortality rates associated with diverticular hemorrhage remain high. All patients with massive bleeding require aggressive resuscitation and monitoring. The passage of a nasogastric tube to exclude upper gastrointestinal bleeding and a proctoscopy to determine ongoing bleeding can be accomplished while the patient is being resuscitated. This will facilitate the direction and timing of the remainder of the evaluation. Continuous massive bleeding in a patient whose condition is hemodynamically unstable is an indication for an emergent operation. Because an emergency subtotal colectomy for nonlocalized bleeding portends significant morbidity and mortality rates, every effort should be made to localize the source of hemorrhage and stabilize the patient's condition. This frequently will convert an emergent extensive resection to a segmental excision in an elective or semielective setting. Selective mesenteric angiography is an accurate method not only to localize the bleeding site but also to intervene therapeutically in the patient whose condition is hemodynamically stable. The bleeding rate should exceed 1.0 to 3.0 ml per minute for successful localization. Intraarterial infusion of vasopressin at 0.2 to 0.4 units per minute can then be used to suppress hemorrhage. More recently, selective embolization with thrombotic agents has been used with good success. If bleeding is not controlled with angiographic measures, surgical intervention is indicated. The arterial catheter should be left in place to assist the surgeon with the localization of the bleeding site. Infusion of methylene blue can also be used to facilitate the identification of the bleeding site and limit the extent of resection. If bleeding is controlled with angiography, the vasopressin infusion should be maintained for 12 to 24 hours and gradually discontinued. The catheter should be left in place for an additional period of time, typically 8 hours, should bleeding recur. Recurrent bleeding can again be managed Curr Probl Surg, July

34 with vasopressin. However, surgical intervention should be strongly considered even if the hemorrhage is controlled because recurrent bleeding is likely. Radioisotope scans are of 2 basic types: technetium 99m labeled sulfur colloid or tagged red blood cells. The 99mTc sulfur colloid is cleared from the circulation within several minutes; pooling of extravasated material into the intestinal lumen identifies gastrointestinal bleeding. The main advantage of this technique is the short time it takes to accomplish. Labeled erythrocytes have a much longer circulating half-life that allows for repeated scanning over 24 to 36 hours. As a result, this study can be used to identify intermittent bleeding. Both tagged red blood cells and 99mTc sulfur colloid can detect extremely slow rates of bleeding, as low as 0.1 ml per minute. The clinical success of radioisotope scans for localizing the site of hemorrhage is variable; reported localization accuracy rates range from 24% to 91%. 88 The reasons for the relatively poor localization rates vary. Blood within the intestinal lumen does not remain stationary, and migration can distort the findings. Anatomic variation and the mobility of the gastrointestinal tract may superimpose adjacent loops of bowel, also making an accurate interpretation difficult. Although bleeding scans are extremely sensitive for detecting active bleeding, surgeons remain reluctant to proceed with segmental colon resection solely on the basis of the results of a positive red blood cell scan. Colonoscopic evaluation of patients has been advocated for acute lower gastrointestinal hemorrhage. In general, this is an accurate technique to localize bleeding and provide both diagnostic and therapeutic measures. It should be noted, however, that centers that advocate this method have experienced staff and well-equipped facilities that are crucial to the successful treatment of these patients. With moderate to massive bleeding, it is difficult to clear the colon even with irrigation systems and to visualize adequately the bleeding source to intervene therapeutically. Colonoscopy is the test of choice for those patients with self-limited bleeding. For patients with moderate bleeding that has stopped spontaneously, our preference is to admit them to the hospital for observation and colonic lavage then to proceed with colonoscopy within the next 12 to 24 hours. Patients with less severe bleeding are prepared for urgent colonoscopy on an outpatient basis. The indications for emergent surgical intervention for lower gastrointestinal bleeding are hemodynamic instability, a transfusion requirement greater than 2000 ml in 24 hours, and recurrent massive hemorrhage. The operation may be either segmental or subtotal, depending on the success of preoperative localization. If the bleeding site has been localized, a seg- 492 Curr Probl Surg, July 2000

35 TABLE 2, Types of diverticular fistula Coloappendiceal Colocoxal Colocolonic Colocutaneous Coloenteric Coloepidural Colouterine Colovenous Colo~astric Coloperineal Coloperianal Colosalpingeal Coloureteral Coloureterovesical Colovaginal Colovesicovaginal Modified from Sonnenshein MA, Cone LA, Alexander RM. Diverticulitis with colovenous fistula in portovenous gas: report of two cases. J Clin Gastroenterol 1986;8:195. mental resection will control the bleeding in 90% of patients. A subtotal colectomy is also effective in controlling bleeding, but this procedure is associated with much higher morbidity and mortality rates. The incidence of recurrent diverticular bleeding is approximately 5% per year. Therefore, the indication for elective resection is controversial. For those patients with recurrent hemorrhage, operation is recommended, particularly if the site has been localized. Fistula Fistulas occur in 2% of patients with diverticular disease, but in patients undergoing operation for diverticular disease, 20% have fistulas. 36'89 Fistulas are thought to result from a localized inflammatory process usually associated with an abscess that spontaneously decompresses by perforating into adjacent viscera or through the skin. This event usually obviates the need for emergent intervention, provided the abscess has drained adequately. Complex fistulas involving 2 or more organs are unusual, although multiple simple fistulas occur in approximately 8% of patients. 9~ Fistulas occur more frequently in men than in women, presumably because the reproductive organs provide a barrier to fistula formation in women. Not surprisingly, colovesical and/or colovaginal fistulas are more common in women who have undergone a hysterectomy. 55 The most frequent fistula associated with diverticulitis is a colovesical fistula (65%); colovaginal, colocutaneous, and coloenteric fistulas are also commonly encountered. A more complete list of reported sites of fistulas is presented in Table 2. Colocutaneous fistulas are encountered more often in patients who have had previous abdominal surgery and, in particular, those patients with a history of previous operation for diverticular disease. 91 Fistula formation and other complications of diverticular disease have been suggested to occur more often in immunocompromised patients. Curr Probl Surg, July

36 The clinical findings associated with fistulas are often variable, given their intermittent patency. The diagnosis in such cases can be elusive and is not always easily documented with standard diagnostic studies. The clinician must have a high index of suspicion and may need to repeat diagnostic studies at a time when patients are symptomatic to document the presence of a fistula. The most commonly used diagnostic tests include the CT scan, contrast enema, cystoscopy, vaginoscopy, and fistulograms. 92 The use of oral activated charcoal can also be helpful for documentation of the presence of small, minimallysymptomatic fistulas. Although diverticulitis is the most common cause of enterovesical fistulas, it must be kept in mind that pelvic malignancies and Crohn's disease can also be encountered. A review by Pontari and colleagues 94 from Yale University and its affiliated hospitals noted a variation in clinical presentation and patient age associated with fistulas of different causes. Patients with diverticular disease as the cause of their fistula were older and primarily had pneumaturia. Those patients with neoplastic causes were more likely to have fecaluria, gastrointestinal symptoms, and/or hematuria. Patients with Crohn's disease were 20 years younger on average than patients with cancer or diverticulitis and had pneumaturia, an abdominal mass, and pain more frequently. Because most fistulas associated with diverticular disease and other causes can be stabilized with medical management, it is unusual that urgent intervention is required. A review of our own experience at the University of Minnesota and that of Kirsh and colleagues 95 reveals a reduction in morbidity and mortality rates and a shorter hospital stay in patients treated with a primary anastomosis. Therefore, every effort should be made to stabilize the patient's condition, to drain any intraabdominal abscess, and to resolve any acute inflammation to facilitate a 1-stage procedure. Because the primary pathologic findings with diverticular fistula are within the intestine, management of the fistula tract and associated viscera should be kept simple. If the fistula tract is obvious or associated with an abscess, the tissue should be debrided, and the opening should be repaired with absorbable suture. If the opening is difficult to identify, simple drainage along with resection of the involved bowel should be adequate. Resection of the bladder, vagina, adjacent bowel, or other tissue involved in the inflammatory reaction is reserved for patients with suspected malignancy or, in rare instances, in whom the viability of the tissue is marginal. Obstruction~Abscess Colonic obstruction as a consequence of diverticular disease is uncommon, accounting for 10% of large bowel obstructions. 96 Partial obstruction 494 Curr Probl Surg, July 2000

37 from edema, spasm, and acute and chronic inflammatory changes, however, is encountered frequently. Complete obstruction generally occurs when an acute abscess is superimposed on a chronic stricture. In the past, this situation necessitated urgent surgical intervention and most frequently a staged procedure such as a Hartmann's procedure. Percutaneous abscess drainage (PAD) has become the treatment of choice for simple, welldefined collections associated with a variety of inflammatory disorders. In most cases, successful drainage and aggressive medical management will alleviate obstruction, permitting preoperative bowel preparation with subsequent primary resection and anastomosis. In selected patients, percutaneous drainage may provide complete resolution of the inflammatory process, negating the need for surgical intervention altogether. The experience at the University of Minnesota with PAD, treating 82 patients with 111 abscesses between 1990 and 1994, suggests PAD to be extremely successful. 97 The overall success rate with PAD was 76%, and 100% of the simple unilocular abscesses resolved with PAD. Factors associated with diminished success were multiloculated collections, abscesses associated with enteric fistula, and abscesses containing stool or semisolid material. An anastomotic leak is the most frequently cited cause for abscess formation, accounting for 35% of the abscesses; diverticular disease accounts for 23% of the abscesses overall. Diverticular abscesses managed with PAD allowed resolution of acute problems for all patients in this series. Of the 7 patients treated in this manner, only 2 patients have subsequently required operation, and both of these patients experienced no complications and were treated on an elective basis for chronic partial obstructive symptoms. The 5 remaining patients are now more than 5 years from their PAD and remain asymptomatic. A long-term review of a larger series of patients is warranted, but nonoperative treatment may be prudent in some patients. Perforation Free perforation is fortunately uncommon with diverticular disease. When it does occur, it is often associated with generalized peritonitis. In an effort to classify the inflammatory complications and the extent of peritonitis associated with diverticular perforation, Hughes and colleagues 9s and Hinchey and colleagues 99 have proposed a scheme to grade the degree of involvement. Unfortunately, no single schema has been adopted uniformly, making comparisons of various published studies regarding optimal surgical management difficult to interpret. Furthermore, much of what has been published is retrospective, making accurate staging suspect. In general, there are 4 basic surgical options for Curr Probl Surg, July

38 the treatment of complicated diverticulitis: (1) the classic 3-stage colostomy and drainage only, (2) colostomy and resection (Hartmann's), (3) primary resection, anastomosis, and proximal diversion, and (4) primary resection with anastomosis. Currently, there is little support for colostomy and drainage alone because the septic focus is not adequately treated. The basic tenets of modern treatment for complicated diverticular disease should include control of sepsis, resection of diseased tissue, and restoration of intestinal continuity with or without a protective stoma. Primary resection is supported by a number of studies. Rodkey and Welch n and Auguste and colleagues 1~176 noted prolonged hospitalization and disability in patients treated with a staged operation. Finlay and Carter 1~ and Nagorney and colleagues 1~ reported greater morbidity in patients treated with colostomy and drainage. The Mayo Clinic review also reported a higher mortality rate in patients with colostomy and drainage (26% vs 7%) in those patients treated with resection. Krukowski and Mathesen 79 surveyed the literature for any reports on emergency procedures for perforated diverticulitis, and they also noted a survival advantage with primary resection. In this collected series, the mortality rate for primary resection was 11% versus 25% for drainage without resection. On rare occasions, the inflammatory changes in the pelvis and retroperiteneum are so extensive that mobilization and resection are felt to be unsafe. An adequate incision, synchronous lithotomy position, ureteral stents, and intraoperative endoscopy usually facilitate safe resection through normal tissue planes. When resection is not possible, a classic 3- stage procedure is advisable. To minimize the complications that accompany this approach, one should debride and drain the pelvis to the greatest extent possible. Proctoscopy, irrigation, and wash out of the distal colonic segment can also help to reduce continued fecal contamination and sepsis. After successful mobilization of the diseased segment of the colon, the surgeon must decide whether to perform a primary anastomosis. In this emergency setting, preoperative bowel preparation is not possible and intraoperative lavage should be considered, particularly if a large fecal load is encountered. This adds an additional 30 minutes on average to the procedure and can increase the risk of peritoneal contamination. The benefit of avoiding a second pelvic procedure generally outweighs the risks associated with on-table lavage. The surgeon must continuously reflect on the patient's overall wellbeing throughout the preoperative assessment and operative procedures. Factors outside the conduct of the operation do influence the success of an anastomosis and the overall mortality rate. Contraindications to prima- 496 Curr Probl Surg, July 2000

39 ry anastomosis include malnutrition, severe anemia, feculent peritonitis, immunosuppression, and questionable viability of the bowel. Technical problems with the anastomosis, the presence of a chronic abscess cavity, and mild systemic illness constitute relative contraindications for primary anastomosis. In these situations, the anastomosis can be performed, and a temporary proximal diverting ileostomy can be created to protect the anastomosis for an indeterminate period of time. This protects the patient from the consequences of an anastomotic leak and avoids the difficulty associated with a Hartmann's reconstruction. The Hartmann procedure is reserved for a select group of patients with extensive disease and severe comorbid conditions. A substantial percentage of these patients, however, will never have a colostomy closure. Summary Complicated diverticular disease remains a serious and frequently lifethreatening condition. Successful treatment requires timely and thoughtful judgment of the clinical situation, with selective intervention tailored to the individual patient. Whenever possible, the surgeon should strive to convert emergency situations to elective procedures to. reduce morbidity and mortality rates. Continued advances in the preoperative management should enhance the surgeon's ability to temporize complicated problems associated with diverticular disease and facilitate 1-stage procedures for more patients. Special Problems Recurrent Diverticular Disease after Previous Resection Recurrent diverticulitis after previous sigmoid resection can be a very difficult diagnosis and treatment problem. Fortunately, this phenomenon is rare. A compilation of large series of resections for diverticular disease shows an incidence of recurrent diverticulitis after resection from 1% to 10.4%. 42' (Fig 10). Given the high incidence of recurrent diverticulitis in patients who have not had a resection, it is somewhat surprising that recurrence rates after sigmoid resection are low. In one series of 136 patients followed by Wychulis and colleagues, 1~ 7% of patients had left lower quadrant pain, and 5% of patients were diagnosed as having recurrent diverticulitis. Benn and colleagues, 42 in a series of 501 patients who underwent left-sided resection for diverticulitis, found recurrent symptoms in 52 patients (10.4%). However, re-resection was necessary in only 15 patients (3%). The timing for recurrence in this series was from 1 month to almost 12 years. Curr Probl Surg, July

40 Proximal segment in anastomosis Transverse colon rectal Descending colon anastomoses Sigmoid colon Sigmoidal anastomoses 1//I ;t/ijl'l 2 (1.1%) Anastomotic 3 (0.9%) Itllllll]l/I /t/'tllllil,eaks \t//t/l!it)/ \/ktlljllu t= (s 7%) Recurre.t 40 (t24%) ~",~illllly " diverticulitis A ~ 4 (2.2%) Re-operation 11 (3.4%)~ lal Rectum 81 Descending colon anastomosis Sigmoid 132 Recurrent diverticulitis 5 (6.2%) 30 (22.7~1 B Fig lo. A, Level of anastomosis and clinical outcome in 501 patients after sigmoid resection for diverticular disease. B, Incidence of recurrent diverticulitis in the subset of 213 patients from whom the entire proximal sigmoid colon was removed with anastomosis of the descending colon to the rectum or the distal sigmoid colon. (From Bell AM, Wolff BG. Progression and recurrence after resection for diverticulitis. Semin Colon Rectal Surg 1990;1:2. With permission.) Patients who have symptoms of recurrent diverticulitis after resection should be evaluated carefully with a differential diagnosis that includes inflammatory bowel disease, infectious colitis, carcinoma, ischemic colitis, leiomyosarcoma, and irritable bowel syndrome. If possible, previously resected specimens should be re-reviewed by surgical pathologists. An association between diverticular disease and Crohn's colitis has been found in at least one study, 1~ with the association particularly strong, as might be expected, in elderly patients. Up to 30% of patients who have diverticulosis may also have irritable bowel syndrome, and the distinction can frequently only be made by the absence of leucocytosis and fever. The usual evaluation for diverticular disease includes a CT scan, contrast studies, and endoscopy. In the acute setting, colonoscopy must be used cautiously. The necessity for urgent reoperation in patients with recurrent 498 Curr Probl Surg, July 2000

41 diverticulitis should be very unusual, but patients may have the same complications (eg, perforation, abscess, obstruction, and fistula). Emergency operation in patients with recurrent diverticulitis should be a last resort because almost certainly a colostomy will be required, with all of the inherent difficulties of an unprepared bowel and with the re-resection bearing the hazards of bleeding and ureteral injury caused by the previous scarring and current inflammation. Ideally, a patient with acute recurrent diverticulitis would be able to be stabilized and treated conservatively with intravenous antibiotics and other standard maneuvers including bowel rest and percutaneous drainage of abscesses to avoid operation in the acute setting. Margins. The best strategy for the avoidance of the difficulties of recurrent diverticulitis after resection is adequate sigmoid resection at the first operation, With selection of soft, pliable bowel proximally in the descending colon anastomosed to the upper rectum distally, because diverticula in the rectum are rare. It is not necessary to resect all of the diverticular-bearing colon because patients frequently have extensive diverticulosis that affects the descending colon and transverse colon or even pancolonic diverticulosis. Ninety-eight percent of colonic diverticulitis is referable to the sigmoid colon. A Mayo Clinic study followed 61 patients who had undergone elective sigmoid resections for diverticular disease for at least 5 years with barium enema examinations. 41 The progression of diverticulitis was noted in 9 patients (14.7%) and was minimal. Seven patients (11.4%) had symptoms of recurrent diverticulitis, but only 3 of these patients had experienced the progression of diverticulosis. Indeed, diverticulosis of nonsigmoid origin may be an acquired connective tissue defect of completely different cause, as opposed to the dysmotility phenomenon caused by hypertrophic muscle in the sigmoid colon, creating the genesis of high-pressure zones with diverticula formation. Although abnormal compliance has been demonstrated consistently in the sigmoid colon of patients with diverticular disease, some abnormality provided by metric response to balloon distention may occur in the descending colon and rectum after resection, 1~ but this does not seem to be clinically significant. A noncompliant bowel wall is due to muscle hypertrophy and intrinsic derangement of collagen fibers in those patients with diverticular disease. 11~ The disordered compliance is also associated with increased elastin between muscle cells and the taeniae coli. 33 Although these findings in the descending colon and upper rectum after resection are interesting, they appear to have little relation to the clinical course after resection. The selection of proximal bowel for anastomosis should be in soft, pliable colon, usually found in the descending colon, although Curr Probl Surg, July

42 splenic flexure mobilization may be necessary to obtain an adequate length, particularly after a previous resection. The distal margin should be located at the so-called rectosigmoid junction or upper rectum. This is located near the sacral promontory where there is convergence of the teniae coli to form a continual sheet of longitudinal muscle. Dissection of the presacral space posterior to the rectum and mobilization of the upper rectum are frequently required to obtain added length for comfortable anastomosis. The importance of the distal margin of resection was shown by Benn and colleagues 4z in a study of 501 patients who underwent sigmoid resections for diverticular disease. Recurrent diverticulitis developed in 12.5% of patients in whom the distal sigmoid colon was used as a distal margin, compared with 6.7% of those patients in whom the rectum was used for anastomosis (P =.03). The anastomotic leak rate and reoperation rate were not statistically different. A subset study lu of these patients showed a striking difference in the incidence of recurrent diverticulitis between patients who underwent a descending colorectostomy (6.2%) versus those patients who underwent descending colosigmoidostomies (22.7%; Fig 10). Operation. When the decision for reoperation has been made and all attempts to convert acute recurrent diverticulitis to an elective situation have been made, the patient is marked on the fight and left lower quadrants before operation for possible colostomy or ileostomy. If at all possible, ureteral stents should be placed because the left ureter, in particular, will likely be found in close approximation bound in scar tissue to the anastomosis. Many urologists will now perform this maneuver with the patient in the synchronous position in the appropriate operating room; this takes only a few minutes. The positioning of patients in the synchronous position allows a stapled anastomosis after re-resection. If there is dense scar tissue surrounding the old anastomosis or phlegmon, the dissection should be started higher on the colon, working in front of Gerota's fascia, identifying the ureter, and proceeding distally. Likewise, it is sometimes possible to begin with the rectal mobilization, identify the ureter, and dissect proximally on the colon until the colon is completely mobilized. Sharp dissection with scissors or electrocautery is preferred to blunt dissection. Splenic flexure mobilization, and even mobilization of the transverse colon, may at times be necessary. Preservation of the omentum is preferred. Again, the principles of soft, pliable, proximal colon, whether descending colon or transverse colon, with anastomosis to upper rectum are required. In emergency situations, an on-table lavage, a subtotal colectomy, or a Hartmann procedure may be performed. If the latter procedure 500 Curr Probl Surg, July 2000

43 is performed after previous operation, the chances of reanastomosis at a later date are diminished considerably. If possible, an anastomosis with a proximal diversion, such as a loop ileostomy, should be performed if the usual requirements for anastomosis are met. If the rectum has been extensively mobilized posteriorly, closed suction drains are usually placed in the pelvis. Right-sided Diverticulitis In contrast to Western countries where diverticulitis is chiefly localized to the sigmoid colon, diverticulosis in Asia occurs on the fight side in 35% to 84% of cases. 18,11Ll13 Although the diet has changed in the Far East to a more Western cuisine, diverticular disease continues to be found predominantly on the fight side. TM Right-sided diverticulitis occurs at an average of 40 years of age, whereas sigmoid diverticulitis occurs at an average of 59 years of age. 18, Therefore, it would seem logical that there is a genetic basis for the development of acquired diverticulosis in Asian populations. Much has been made of the difference between true diverticula, which contain all layers of the bowel wall and are thought to be congenital, and false diverticula, which are made up of mucosa, muscularis mucosa, and either attenuated or totally absent submucosa and musculafis propria. Diverticulitis can occur in both, and for practical purposes, the differentiation of true from false diverticula has little or no relevance in the clinical setting. Appendiceal diverticulitis was first described in 1893 and is an uncommon but distinct pathologic entity apart from true appendicitis. 119 Right-sided diverticula in Western populations tend to be solitary and in Asian populations tend to be multiple, which may account for the increased incidence of diverticulitis in that population. Estimates of cecal diverticulitis in the continental United States are approximately 1 in 1100 laparotomies for an acute abdomen. 12~ One recent study from the Netherlands 121 has reported a frequency of fight colonic diverticulitis of 1 in 34 appendectomies, which is 9 times higher than that reported in other series. The complications of right-sided diverticulitis are the same as for the left and include abscess, fistula, phlegmon formation, perforation, obstruction, and sepsis. Diagnosis. The diagnosis of right-sided diverticulitis is very difficult to distinguish from acute appendicitis, with the chief symptoms being fight lower quadrant pain (in most patients), nausea, emesis, leukocytosis, and fever. An abdominal mass can be appreciated in 26% to 68% of cases. 122,123 Indeed, the diagnosis is established at operation in more than two thirds of cases. Only if the patient has had a previous appendectomy, Curr Probl Surg, July

44 previous repeated episodes of right lower quadrant pain, or a previous diagnosis of fight-sided diverticulosis can a preoperative diagnosis be made easily. Nevertheless, with the advent of appendiceal CT scans, which are (according to one study TM) 98% sensitive and 98% specific for the diagnosis of acute appendicitis, and advances in ultrasound scanning, the diagnosis can now be made more accurately before operation. Indeed, with the combination of CT and ultrasound scanning, 41 of 44 patients TM were treated conservatively with repeat radiologic examinations and antibiotics, with only 2 of the 41 patients requiring elective surgery. Five patients had recurrent symptoms. The differential diagnosis for right-sided appendicitis is chronic cholecystitis, appendicitis, mesenteric adenitis, ischemic colitis, pelvic inflammatory disease, pancreatitis, Meckel's diverticulitis, left-sided diverticulitis, and duodenal ulceration. CT and ultrasound scanning are the most effective diagnostic tools, with barium enema and colonoscopy, particularly in the acute setting, being less effective. Laparoscopy may be useful, particularly for differentiating appendicitis from fight-sided diverticulitis. Treatment. There has been much disagreement about the appropriate management of right-sided diverticulitis. In Asian countries, where the diagnosis has been made before operation, conservative treatment with antibiotics has been popular and effective. Diverticulectomy has been advocated for patients with inflamed or perforated diverticula. Right hemicolectomy has been reserved for patients in whom a malignant neoplasm cannot be excluded. In one series, 40 patients with nonperforated right-sided diverticulitis were treated with antibiotic therapy, and 25 patients were treated with diverticulectomy. 19 Only 3 patients underwent right hemicolectomy. One patient had recurrent episodes of right colon diverticulitis and underwent subsequent colectomy. There were no deaths, and the morbidity rate was minimal. A recent series by Lane and colleagues 125 of 49 patients, which is the largest single institution review reported in the mainland United States, reports a more aggressive approach with right hemicolectomy being performed in 80% of the patients and diverticulectomy being performed in only 14% of the patients. Appendectomy with drainage of an intraabdominal abscess was performed in 3 patients. Of the patients undergoing hemicolectomy, there were no deaths and a low complication rate of 18%. The most serious complications were 2 anastomotic leaks, the first of which required proximal diversion for peritonitis; intestinal continuity was reestablished in this patient 3 months later. The second leak appeared as a fistula 21 months after operation and resolved without surgical intervention. All patients who underwent appendectomy with drainage 502 Curt Probl Surg, July 2000

45 required subsequent hemicolectomy for continued inflammation. The 7 patients who underwent diverticulectomy did well, except for 1 patient who subsequently required right hemicolectomy for continued symptoms. Therefore, the choice of operation is usually made on the basis of the clinical findings at operation, except in patients in whom a preoperative diagnosis is made, a bowel prep can be effected, and a procedure can be performed electively. If right-sided diverticulitis is diagnosed during the operation, the options are conservative treatment (which includes only appendectomy and closure of the abdomen with postoperative antibiotic therapy) or appendectomy and diverticulectomy (if the lower portion of the diverticulum is noninflamed) or right hemicolectomy. Because right hemicolectomy, even with a nonprepared bowel, can be accomplished with low morbidity and few deaths, this would seem to be the procedure of choice 126 at this time. Right-sided diverticula can also be a source of lower gastrointestinal bleeding and are diagnosed frequently at colonoscopy. Such bleeding usually stops spontaneously, as it did in 16 of 25 cases in one report. 127 The other 9 patients in this series required fight hemicolectomy because of continuous or recurrent bleeding. There were no deaths, and morbidity was low. Bleeding in those patients treated conservatively did not recur, but the follow-up period was short. Atypical Diverticulitis The more common presentations of acute diverticulitis, with typical symptoms of left lower quadrant pain, fever, alterations in bowel habits, and elevated white blood count, which may become relapsing in several distinct episodes and thus chronic, have been described earlier in this monograph. Another form of acute diverticulitis is subacute diverticulitis, which may be a moderate or severe episode of diverticulitis with some resolution with antibiotics and conservative treatment but does not resolve completely and continues in a smoldering fashion with perhaps low-grade fever, left lower quadrant pain, and altered bowel habits for up to several months. These patients usually undergo elective resection when it becomes clear that the disease will not respond to more conservative measures. Complicated diverticulitis has also been well described as obstruction, mass or abscess, fistula, hemorrhage, or perforation. The diagnosis of these complications is relatively easy, and the solutions are more concrete. However, there is a third form of chronic diverticulitis in which the diagnosis is obscure and in which the surgical outcomes are even more difficult to determine (Table 3). Patients with atypical, or smoldering diverticulitis, may experience left lower quadrant pain and alteration in bowel Curr Probl Surg, July

46 TABLE 3. Types of diverticulitis Acute diverticulitis Typical, relapsing (chronic) Subacute Complicated diverticulitis Obstruction Mass/abscess Fistula Hemorrhage Perforation Chronic diverticulitis Atypical, "smoldering" Atypical presentation by site habits, but without obvious episodes of fever, and frequently without an elevated white blood count. Yet on operation, the resected specimen often shows typical pathologic findings of diverticulitis. These symptoms have been present for 6 months to many years. The chronic inflammation is even more subtle than that found in subacute diverticulitis, and the differential diagnosis of chronic colonic ischemia, irritable bowel syndrome, intermittent volvulus or intestinal obstruction, or gynecologic or urologic abnormalities is difficult. We have found that 47 (5.05%) of 930 patients who underwent sigmoid resection for diverticular disease (including complications of diverticular disease, emergencies, and second stage procedures) had atypical diverticulitis. Follow-up was complete in 79% of these 47 patients who were diagnosed as having "smoldering" diverticular disease. The chronicity of the left lower quadrant pain and the presence of diverticula, but absence of hallmarks of diverticulitis, characterized this group. Many of these patients had been treated for irritable bowel syndrome for long periods of time without satisfactory results. Sigmoid resection was formed in all 47 patients, and evidence of acute or chronic inflammatory changes in the sigrnoid colon with diverticula was present in 76% of resected specimens. Complete resolution of symptoms occurred in 70% of the patients, and 84% of the patients were pain free. 129 Such results lead to the obvious conclusion that this entity is an under-diagnosed but important element of diverticulitis. Atypical presentations by site is another difficult area of diagnosis within the spectrum of diverticular disease. Chronic hip, thigh, and knee infections with enteric flora, left adnexal masses in middle-aged women, extrasphincteric perianal or ischial rectal masses, other atypical inflammation in the perineum and genitalia, subcutaneous emphysema of the 504 Curr Probl Surg, July 2000

47 groin and abdominal wall, and hepatic abscesses (lacking a primary focus elsewhere in the body) are all examples of atypical presentations of diverticulitis, which are usually chronic by the nature of the length of time for these manifestations to Occur. 129 The CT scan is usually the best diagnostic study for correct diagnosis, but if a chronic abscess has been drained, a sinogram or fistulogram may well lead to the correct diagnosis. Treatment with standard sigmoid resection can then be undertaken. Diverticulitis in the Irnrnunocompromised Patient The immunocompromised patient has 2 major problems as a result of a dysfunctional immune system: predisposition to infection and difficulties with wound healing. Patients receiving exogenous corticosteroids have fewer and more dysfunctional circulating leukocytes with a relative neutrophilia. 13~ There is a decrease in the number of T lymphocytes and reduced monocyte and eosinophil counts. Alterations in chemotaxis, complement receptor expression, and cytokine secretion lead to T-lymphocyte and monocyte-macrophage functional deficiencies. Corticosteroids enhance protein breakdown, inhibit fibroblast proliferation, and decrease protein synthesis, creating a catabolic state that weakens normal connective tissue and leads to the impairment of wound healing. An additional problem is the masking of acute inflammatory episodes, particularly of abdominal origin, with masking of peritoneal signs and other signs and symptoms. Because of chronic exogenous steroid therapy, chemotherapy, or chronic renal failure, patients theoretically have a greater colonic wall weakness with greater colonic dysmotility. It is not known whether such patients have a greater incidence of colonic diverticulosis. Diverticulosis has been reported in 45% to 50% of patients with renal failure and in 13% of patients who have undergone transplantations. TM It seems that patients with uremia experience the development of diverticulosis earlier than their healthier counterparts. A particularly high incidence of diverticulosis has been noted in patients with polycystic kidney disease, with an unusually high rate of diverticular perforation in such patients. 132 Even though conclusive proof is lacking that the incidence of diverticulosis is higher in immunocompromised patients and patients with uremia, the incidence of complicated diverticulitis in immunocompromised patients is unquestioned. In one study of 209 patients, 133 there were 40 immunocompromised patients and 169 nonimmunocompromised patients with acute diverticulitis. Free perforation occurred in 43% of immunocompromised patients and in only 14% of nonimmunocompromised patients. The postoperative morbidity rate was 65% in immunocompro- Curr Probl Surg, July

48 mised patients and 24% in nonimmunocompromised patients. The postoperative mortality rate was similarly increased, at 39% (9/23 patients) and 2% (1/55 patients), respectively. This greater risk of free perforation and a greater need for operation have led to a different management strategy in immunocompromised patients with colonic diverticulosis. In another study, TM patients with polycystic kidney disease as a cause of renal failure had a significantly higher rate of complicated diverticulitis. Although patients with polycystic kidney disease comprised only 9% of the total transplantation population in this study, they accounted for 46% of cases of diverticulitis. The authors could not relate the use of cyclosporine or the source of the donor (living related versus cadaveric) to the increased incidence of diverticulitis. A study of lung transplant recipients found that 3 of 35 patients (8.6%) had perforated sigmoid diverticular disease that occurred within 4 weeks of transplantation, which was a much higher rate than that reported in other transplantation populations. The authors felt that perforated diverticulitis in the early posttransplantation period might be related to "intense posttransplantation immunosuppression, perioperative hypoperfusion, and increased intraluminal pressure from the use of narcotics and bowel stimulants. ''135 Thus, diverticulitis in the immunocompromised patient is much more likely to be complicated than in the nonimmunocompromised patient. The diagnosis of acute colonic diverticulitis in the immunocompromised patient is more difficult for several reasons. Younger patients with chronic renal failure will experience the development of symptomatic diverticular disease at a younger age than patients in a healthy population; therefore this disease may not be suspected. Corticosteroids will mask signs and symptoms of peritoneal irritation, and the inability to exhibit peritonitis and other related physical findings may be increased commensurately with the dosage of corticosteroids. Because free colonic perforation occurs more commonly in immunocompromised patients, morbidity and mortality rates will be increased. A high index of suspicion in such patients with vague abdominal complaints is essential for reducing these statistics. The abdominal and pelvic CT scan with contrast is the primary diagnostic study. Once the diagnosis is established, all immunosuppression medications should be stopped except for exogenous corticosteroids. 13~ Such patients may not require a big boost in the preoperative setting. Otherwise, patients may be treated in a way similar to immunocompetent patients except for the use of nephrotoxic antibiotics. Immunocompromised patients with acute uncomplicated diverticulitis may be treated medically with bowel rest and intravenous antibiotics. Percutaneous drainage of pericolic abscess may be performed. For 506 Curr Probl Surg, July 2000

49 patients with colonic perforation, primary resection with anastomosis should be avoided (particularly in cases with fecal peritonitis) because of the impaired immune system and impaired wound healing. Abdominal wound disruption is a relatively frequent problem; therefore the use of retention sutures should be considered, Vitamin A in a dosage of 25,000 IU administered daily may reduce the effects of steroids, to some extent, on wound healing. In general, patients having 1 episode of documented diverticulitis in the immunocompromised population should undergo elective resection as the circumstances dictate. Giant Colonic Diverticulum The condition called giant colonic diverticulum first described by Bonvin and Bonte in affects men and women equally and is rare, with between and cases reported depending on how the diverticulum is classified. These diverticula occur most often in patients over the age of 50 years and have an average diameter of 13 cm. 139 Diverticula as large as 30 to 40 cm in diameter have been described. 14~ The sigmoid colon is almost exclusively the site of occurrence, although such diverticula have been reported in the transverse and descending colon. There are various theories as to how these giant colonic diverticula develop. One proposal includes a ball-valve-type mechanism that allows air into a diverticulum; this air becomes trapped by being able to pass through a narrow neck into the diverticulum, but not the reverse. Another theory is a cyst formation by gas-forming microorganisms with inlet obstruction. Because some diverticula have fairly wide necks, the latter explanation does not seem plausible. Two types of diverticula have been described. The type I diverticulum is a pseudodiverticulum. 138 The wall of this diverticulum contains fibrous tissue with some inflammatory cells but lacks a distinct smooth muscle layer. This is the most common type of giant colonic diverticulum and accounts for almost 90% of the cases. The type II giant colonic diverticulum is a true diverticulum that contains all the layers that are normally found in the bowel wall and has a well-developed smooth muscle layer. Because symptoms such as vague abdominal pain and bloating or an abdominal mass are similar with both types of diverticulum, the classification has little clinical impact and is therefore moot. Occasionally, giant colonic diverticulum may perforate, cause small bowel obstruction because of adherence to adjacent small bowel loops and other organs, cause volvulus, or become infarcted. The simplest, and probably the most effective diagnostic test for this entity, is a flat and upright film of the abdomen. These diverticula usually occur in the presence of other diver- Curr Probl Surg, July

50 ticula; if there is a question about the diagnosis, a barium enema or CT scan will usually easily distinguish other entities in the differential diagnosis, such as emphysematous cholecystitis, cholecystoenteric fistula, pancreatic pseudocyst, Meckel's or jejunoileal diverticula, colonic duplications, sigmoid volvulus, and urinary bladder abnormalities. The treatment of patients with diverticulitis of a giant colonic diverticulum with an acute presentation of nausea, fever, and left lower quadrant irritation is similar to that for patients with ordinary sigmoid diverticulitis. Whether in the acute setting or with chronic symptoms, such diverticula should eventually be removed. In the elective setting, a sigmoid resection with end-to-end anastomosis is preferable over diverticulectomy, because many times the base of these diverticula is inflamed. Nevertheless, diverticulectomy has been performed in approximately 25% of procedures performed through In the acute setting, a Hartman procedure may be indicated. REFERENCES 1. Mayo WJ, Wilson LB, Giffin HZ. Acquired diverticulitis of the large intestine. Surg Gynecol Obstet 1907;5: Painter NS, Burkitt DP. Diverticular disease of the colon: a deficiency disease of Western civilization. Br Med J 1971 ;2: Hughes LE. Postmortem survey of diverticnlar disease of the colon: I. Diverticulosis and diverticulitis. Gut 1969;10: Painter NS, Burkitt DP. Diverticular disease of the colon: a 20th century problem. Clin Gastroenterol 1975;4: Parks TG. Natural history of diverticular disease of the colon. Clin Gastroenterol 1975;4: Imbembo AL, Bailey RW. Diverticular disease of the colon. In: Sabiston DC Jr, editor. Textbook of surgery. 14th ed. Philadelphia: WB Saunders; p Gostout CJ, Wang KK, Ahlquist DA, Clain JE, Hughes RW, Larson MV, et al. Acute gastrointestinal bleeding: experience of a specialized management team. J Clin Gastroenterol 1992;14: Browder W, Cerise EJ, Litwin MS. Impact of emergency angiography in massive lower intestinal bleeding. Ann Surg 1986;204: Boley S J, Sammartano R, Adams A, DiBiase A, Kleinhaus S, Sprayregen S. On the nature and etiology of vascular ectasias of the colon: degenerative lesions of aging. Gastroenterology 1977;72: Boley S J, DiBiase A, Brandt LJ, Sammartano RJ. Lower intestinal bleeding in the elderly. Am J Surg 1979;137: Uden P, Jiborn H, Jonsson K. Influence of selective mesenteric arteriography on the outcome of emergency surgery for massive lower gastrointestinal hemorrhage: a 15-year experience. Dis Colon Rectum 1986;29: Rodkey GV, Welch CE. Changing patterns in the surgical treatment of diverticular disease. Ann Surg 1984; 200: Curr Probl Surg, July 2000

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