CLINICAL MANAGEMENT. Lower Gastrointestinal Bleeding. Clinical Case. Background

Transcription

1 GASTROENTEROLOGY 2006;130: CLINICAL MANAGEMENT Loren Laine, M.D. Clinical Management Editor University of Southern California Los Angeles, California Lower Gastrointestinal Bleeding DON C. ROCKEY Department of Medicine, Division of Digestive and Liver Disease, University of Texas Southwestern Medical Center, Dallas, Texas Clinical Case A 70-year-old man was admitted to the hospital with repeated episodes of red blood per rectum beginning about 12 hours before admission. The patient had a history of hypertension for which he was prescribed a diuretic and ACE inhibitor. He denied any previous gastrointestinal (GI) diseases, abdominal pain, weight loss, or prior change in bowel habits. There was no family history of colon cancer. He had not been screened for colon cancer. On admission his heart rate was 96 supine and 118 when upright. His blood pressure was 124/90 upright and 110/72 supine. The hemoglobin was 11.0 g/dl with a hematocrit of 32% and MCV of 90 fl (his baseline hemoglobin was approximately 14 g/dl). His BUN level was 13 mg/dl and creatinine level was 0.8 mg/dl. Background Lower GI bleeding encompasses a wide clinical spectrum ranging from trivial bleeding to massive hemorrhage with shock. Furthermore, while abundant literature emphasizes management options in patients with acute upper GI bleeding, the literature that guides management for lower GI bleeding is more limited. Lower GI bleeding is approximately one-fifth as common as upper GI bleeding and accounts for approximately 20 to 30 hospitalizations per 100,000 adults per year. 1,2 The incidence of lower GI bleeding increases substantially with age, presumably due to the high incidence of diverticulosis and vascular disease in this group. Prognosis in lower GI bleeding varies. However, since most acute lower GI bleeding is self-limited, outcomes are typically favorable. Indeed, the mortality associated with lower GI bleeding is generally considered to be less than 5% and when it occurs, is often a result of comorbid conditions. 1,2 Data are now emerging to aid in predicting outcomes. One study found that the following clinical features were associated with severe bleeding (defined as transfusion of 2 units of blood and/or hematocrit decrease of 20%): heart rate 100 beats/minute; systolic blood pressure, 115 mm Hg; syncope; nontender abdominal examination; bleeding per rectum during the first 4 hours of evaluation; aspirin use; and more than 2 active comorbid conditions. 3 Thus, although the acuity of hemorrhage in patients with lower GI bleeding is usually less than in upper GI hemorrhage, clinical variables important in predicting severity of bleeding and outcome appear to be similar to those identified in upper GI bleeding. Differential Diagnosis In lower GI bleeding, or GI bleeding from any part of the GI tract for that matter, management begins with development of a differential diagnosis (Table 1) (assessment, monitoring, and management of hemodynamic alterations typical of patients with GI bleeding should proceed as well). First, epidemiologic and historical features should be considered. For example, in patients with lower GI bleeding over the age of 65, vascular ectasia, diverticular hemorrhage, or ischemic colitis, are most common, while in young patients, infectious or inflammatory conditions are more likely. 4,5 Other historical features are also important. Patients with previous vascular disease are at risk for ischemic colitis. Patients with comorbid diseases are at increased risk for vascular ectasias. In immunosuppressed patients, lower GI bleeding due to cytomegalovirus (CMV) infection is an important consideration. 6 NSAIDs appear to be associated with lower GI bleeding, especially from diverticula. 7 Abbreviations used in this paper: CMV, cytomegalovirus; LGIB, lower gastrointestinal bleeding by the American Gastroenterological Association /06/$32.00 doi: /j.gastro

2 166 DON C. ROCKEY GASTROENTEROLOGY Vol. 130, No. 1 Table 1. Causes of Lower Gastrointestinal Bleeding and Associated Features Disorder Prevalence Typical age of onset Typical symptoms Volume of bleeding Other features Diverticula Common Elderly Painless Large Vascular ectasia Common Elderly Painless Variable Renal failure Hemorrhoids Common Any Local Small Upper GI source Common Any Upper GI Large Neoplasia Less common Elderly Painless Small IBD Less common Young Tenesmus/Abd. pain Variable Ischemic colitis Less common Elderly Abd. pain Small Vascular disease Radiation proctitis Less common Any Tenesmus Small Radiation Small bowel Less common Any Small intestinal Variable source Rectal varices Rare Any Liver related Large Portal hypertension Colonic ulcers Rare Any None or abd. pain Variable NSAIDs Dieulafoy s lesion Rare Any Abd. Pain Large Symptoms are important to assess. Painless bleeding is typically caused by diverticular bleeding, or vascular ectasia. However, abdominal pain is often associated with inflammation or ischemia as the cause of bleeding. A history of abdominal radiation, previous surgery (eg, abdominal aortic aneurysm repair, aortofemoral bypass grafting, intestinal resection), constipation, change in bowel habit, and anorectal disease or trauma is important to consider in making a correct diagnosis. It is also imperative to evaluate the character of bleeding, which may be difficult, since accounts of hematochezia vary; some have suggested that the color of the blood first seen by the patient is most informative. 8 Bright red blood most commonly indicates a distal source or a rapidly bleeding proximal source, whereas black stool indicates a source proximal to the colon or, rarely, a slowly bleeding right colonic source. In patients with large amounts of blood per rectum and/or unstable vital signs, it is important to exclude upper GI hemorrhage (see below). Specific causes of lower gastrointestinal bleeding. Important causes of lower GI bleeding are highlighted in Table 1. Very rare abnormalities not listed include solitary rectal ulcer, vasculitis, endometriosis, intussusception, portal colopathy, diversion colitis, and GI bleeding in runners. Notably, the source of bleeding cannot be definitively identified in up to 25% of patients. 1,4 The most common cause of lower GI bleeding in the Western world is colonic diverticula, which typically are located in the colonic wall at the sites of penetrating nutrient vessels. The diagnosis of diverticular hemorrhage is usually one of exclusion, most often made by identification of diverticula and excluding other diagnoses. The character of bleeding often helps diagnostically patients with diverticular bleeding generally bleed in bursts, with clinically obvious bleeding, and do not typically exhibit frequent small volumes of bleeding. Importantly, bleeding can be positively identified from a diverticula at the time of endoscopy in a small number of patients. 9,10 Bleeding from diverticula usually stops spontaneously but can recur in 10% to 40% of patients. 11 Colonic vascular ectasias, or angiodysplasias, are a common cause of acute, chronic, and occult lower GI bleeding. They are common in the right colon, but have been identified in all portions of the GI tract. The pathogenesis of vascular ectasias is largely unknown but is probably associated with aging. Colonic vascular ectasias are uncommon among healthy, asymptomatic people and when identified are typically small. 12 Patients with bleeding vascular ectasias often have chronic underlying medical conditions, including renal failure in particular. Overt lower GI bleeding caused by vascular ectasia is clinically indistinguishable from diverticular bleeding, because both are characterized by painless hematochezia. The pace and volume of bleeding, however, usually are less severe with vascular ectasia than with diverticular bleeding. As with diverticular bleeding, the diagnosis of vascular ectasia is most often made by excluding other diseases since colonoscopy most often identifies a vascular ectasia without stigmata of active bleeding, making ascertainment of its role in bleeding difficult. Acute lower GI bleeding from colon carcinoma is uncommon (bleeding from colon cancer is most often occult). Although colonic polyps may bleed, the bleeding is rarely aggressive, and, as with carcinomas, is generally painless, intermittent, and of small volume. Weight loss, intermittent hematochezia, change in caliber of stool, and evidence of chronic bleeding (eg, iron-deficiency anemia) should raise the possibility of bleeding from colonic neoplasia. Post-polypectomy bleeding is an uncommon but important cause of lower GI hemorrhage, 13 reported in up to 3% of patients after polypectomy, 14 although probably less common, in the range of 0.2% to

3 January 2006 LOWER GI BLEEDING %. 15,16 The risk appears to be greatest in patients taking warfarin or after polypectomy of large lesions (note that the risk of bleeding does not appear to be increased in those taking anti-platelet agents 17,18 ). Hemorrhoids are extremely common and are reported to account for 5% to 10% of acute lower GI bleeding episodes, 4 although a bleeding site can rarely be specifically localized. Hemorrhoids cause intermittent lowvolume bleeding, with bright red blood seen on the toilet tissue or around, but not mixed, in the stool. Careful examination of the anorectal area with anoscopy is essential for diagnosis. Since hemorrhoids are common, lower GI hemorrhage should not be ascribed solely to hemorrhoids until other lesions have been excluded. Meckel s diverticulum is a remnant of the vitelline duct present in the distal ileum that contains gastric mucosa, which secretes acid and results in ulceration of adjacent mucosa. Bleeding usually occurs in children, and to a lesser extent in young adults. Bleeding is often brisk and painless; radiolabeled technetium scanning typically makes the diagnosis. Many different diseases can cause colitis ulceration and inflammation in the colon. Included in this group are colitis due to inflammatory bowel disease, 19 infectious colitis (Salmonella species, Escherichia coli especially the O157:H7 variant, Shigella species, Campylobacter species, Clostridium difficile, Cytomegalovirus), radiation colitis affecting the rectum after pelvic radiotherapy, and ischemic colitis. 4,20,21 Bleeding from colitis is usually associated with crampy abdominal pain, tenderness, and perhaps leukocytosis. Bleeding is rarely vigorous. Diagnosis of a specific form of colitis requires integration of the clinical picture, with endoscopic and histologic findings. Potential Management Strategies Management of lower GI bleeding depends in part on the specific diagnosis. In general, the approach to lower GI bleeding is controversial and not yet standardized. Nasogastric Aspiration and Upper Endoscopy First, it is imperative to consider an upper GI lesion, and this is especially true in the context of aggressive bleeding. Nasogastric aspiration can identify an upper GI bleeding site. 22 However, gastric sampling may not detect lesions that are distal to the pylorus, or that have ceased bleeding. It is relatively specific in that, excluding traumatic insertion with iatrogenic bleeding, a positive aspirate is indicative of upper GI bleeding. If there is any question about an upper GI bleeding source, the definitive test is esophagogastroduodenoscopy. Once an upper GI source has been considered and excluded, I recommend focusing on the colon and rectum. Anoscopy/Flexible Sigmoidoscopy I believe that routine anoscopy should be performed as part of the physical examination. It is easy to do, inexpensive, and the best way to detect local anorectal abnormalities such as internal hemorrhoids, anal lacerations, tears, and fistulas. Flexible sigmoidoscopy may be diagnostic for ulcerative or infectious colitis, hemorrhoids, proctitis, or solitary rectal ulcer, eliminating the need for emergency colonoscopy. However, this approach has not been widely studied, and sigmoidoscopy is rarely as informative as colonoscopy. It is important to emphasize that an anal or rectal lesion must be interpreted in context, and may not exclude a more proximal bleeding lesion. Colonoscopy If an upper GI source has been excluded and anorectal disease is unlikely based on history and examination, management options include radiographic localization techniques and colonoscopy. There is little if any role for air-contrast barium enema (and likely computed tomographic colonography) in lower GI bleeding. Thus, in the vast majority of patients, focus should shift to the potential use of colonoscopy. Although use of early endoscopy for the diagnosis and treatment of upper GI bleeding is predicated on sound data, early endoscopy for lower GI bleeding has not been similarly studied or adopted. Historically, colonoscopy has been used largely in an expectant manner, usually after cessation of bleeding and colonic preparation. The reluctance to perform colonoscopy acutely is due to poor visibility, potential for complications, and theoretical concern about the adverse effects of purging the colon in the setting of active GI bleeding. Colonoscopy is attractive in lower GI bleeding because it provides the best opportunity for early diagnosis, and thus early triage. This possibility is supported by 2 studies demonstrating that the length of time from presentation to colonoscopy is an independent predictor of hospital length of stay. 4,23 Essentially, the sooner colonoscopy was performed, the shorter the length of stay, consistent with enhanced diagnostic yield. 4,23 Nonetheless, there is great controversy about timing of colonoscopy. On one hand, urgent colonoscopy appears to be safe, and provides a specific diagnosis in a high proportion of patients. 9,24 28 However, outcome data supporting its use are lacking. In a randomized trial designed to address this issue, urgent colonoscopy was

4 168 DON C. ROCKEY GASTROENTEROLOGY Vol. 130, No. 1 compared with a standard care algorithm (including red blood cell scintigraphy). 28 In this study, a definite source of bleeding was found more often in urgent colonoscopy patients (diverticula, 13; angioectasia, 4; colitis, 4) than in the standard care group (diverticula, 8; colitis, 3) (P.035). However, there were no differences in important outcomes including: mortality, hospital stay, transfusion requirements, early rebleeding, surgery, or late rebleeding at a mean follow-up of approximately 60 months. It is also noteworthy that the definition of urgent and the timing of procedures vary greatly both in clinical practice and in published reports. Urgent colonoscopy is typically performed after a purge preparation (usually with a polyethylene glycol-based solution), within 8 hours of preparation. (Some researchers have proposed urgent, unprepared colonoscopy for evaluation of lower GI bleeding. In one analysis of 85 consecutive patients who underwent 126 colonoscopies, a bleeding site was identified in 97%. 25 ) Regardless of the timing of colonoscopy, the consensus opinion is that colonoscopy is the diagnostic procedure of choice in most patients with lower GI bleeding. 29 Whether it should be performed urgently with or without a purge preparation or can be performed expectantly is an open question at this time. If abnormalities are more likely to be found during colonoscopy when it is performed urgently than when it is performed expectantly, it would follow that endoscopic therapy would be more likely in this circumstance. Approximately 10% to 15% of patients undergoing urgent colonoscopy had some form of endoscopic therapy. 30 Methods of hemostatic therapy include injection, laser, heater probe, monopolar and multipolar electrocoagulation, and argon plasma coagulation. 14 The most commonly treated abnormalities include diverticula 9,28,30,31 and vascular ectasias. 14,30,32 34 Although data on the effectiveness of endoscopic therapy for lesions causing lower GI bleeding are limited, the global experience suggests that there is likely to be benefit. In the historical control group of a study on endoscopic therapy in diverticular bleeding, 9 17 patients with stigmata of such bleeding were not treated: 9 (53%) rebled, requiring surgical intervention in 6. In the second phase of the study, 10 comparable patients underwent endoscopic therapy with epinephrine (1:20,000), bipolar coagulation (10 to 15 W, 1-second pulses), or both, and no patient rebled. Not all studies, however, have demonstrated such a favorable outcome after endoscopic therapy for diverticular hemorrhage. In a study of 12 patients with diverticular hemorrhage and stigmata of bleeding who underwent similar endoscopic therapy, 1 patient rebled early and 4 rebled late. 31 Thus, albeit very modest, the greatest experience with endoscopic therapy in acute overt lower GI bleeding has been with diverticular bleeding. Endoscopic therapy should be undertaken cautiously in the right colon because of its thin wall. RBC Scintigraphy The use of scintigraphy (technetium-labeled RBC scan), in patients with lower GI bleeding is highly controversial. Although this technique reputedly can detect small amounts of bleeding (as little as 0.1 to 0.5 ml/minute), the technique is associated with a number of problems. Important issues include its lack of therapeutic capability and doubt about its accuracy. Perhaps the most important question surrounding RBC scintigraphy is exactly how reliable it is in directing specific management. In a pooled data set from 14 studies including 343 cases of positive scans in which the site of bleeding was localized by endoscopy, angiography, or surgery, tagged RBC scintigraphy was accurate in 269 (78%) cases. 35 However, it is this author s belief that further definitive therapy is rarely undertaken on the basis of tagged RBC scintigraphy alone. Angiography Angiography may provide accurate localization of rapidly bleeding lesions, although it is able to detect active bleeding only down to a rate of 0.5 to 1.0 ml/ minute. Additionally, angiography can be therapeutic. However, angiography can cause serious complications such as arterial thrombosis, contrast reactions, and acute renal failure. Thus, its use should be carefully considered. Super selective techniques (ie, coil microembolization) have become popular, and appear to offer greater safety. 36 Furthermore, selection of patients for angiography may improve safety and efficacy. In this regard, it appears that patients who develop an immediate blush on RBC scintigraphy appear to have the highest diagnostic yield at angiography. 37 Angiography also has hemostatic capability, achieved by intra-arterial infusion of vasopressin or super selective embolization. Early studies reported a significant risk of bowel infarction, especially with embolization techniques. Various embolic agents have been used, including gelatin sponge pledglets, microcoils, and polyvinyl alcohol particles. Current techniques appear to be more effective and safer than older ones. 36,38 40 Ischemic complications can occur, most likely because of the relatively limited collateral circulation in the colon as compared to the stomach and duodenum). Thus, angiographic therapy must be used with certain reservations. First, these procedures are technically demanding; local expertise will dictate their effectiveness, as well as their priority among therapeutic options. Second, which patients are

5 January 2006 LOWER GI BLEEDING 169 likely to benefit the most from angiographic intervention is unknown. Currently, angiographic therapy currently is most often used in those who are poor surgical candidates. Computed Tomographic Angiography Computed tomographic angiography has been hypothesized to be highly effective to detect vascular ectasia. 41,42 The potential advantages of computed tomographic angiography for detection of vascular ectasia are that it is noninvasive, simple to use, and less costly than conventional angiography. However, it is limited by the inability to assess active bleeding, the reliance upon indirect evidence such as dilated vessels and early venous filling to make the diagnosis, and the lack of therapeutic capability. Surgery Surgery is indicated for some patients with continuous or recurrent lower GI bleeding. 24,43 Surgery is undertaken with the intent of removing the putative bleeding source and is typically recommended for patients with a high transfusion requirement (generally more than 4 units within a 24-hour period or greater than 10 units overall). Accurate preoperative localization of the source of bleeding, particularly by angiography, helps minimize its morbidity and mortality. In one study, the rebleeding rate over a 1-year follow-up period was 14% after segmental colectomy directed by angiography, but 42% after blind segmental colectomy. 44 Surgical intervention in patients with lower GI bleeding without a clear source of bleeding is an important issue. Patients with extensive diverticula in whom bleeding cannot be localized to a specific diverticulum are especially problematic. Blind subtotal colectomy for massive bleeding has been associated with significant morbidity and mortality 11,45,46 and should usually be performed only as a last resort. Recommended Management Strategy Most episodes of acute lower GI bleeding cease spontaneously, regardless of source. Thus, little more than supportive therapy is required for most patients. Figure 1 presents a proposed algorithm for management of acute lower GI hemorrhage. In this specific patient, who was elderly, had acute onset of painless hemorrhage, and had no major risk factors for ischemia or other disorders, the overwhelming likelihood was that he had bleeding from diverticula. However, there were several important considerations. The first was that since we Figure 1. Algorithm for management of acute lower gastrointestinal bleeding. In this approach, urgent colonoscopy is advocated for most patients. Urgent is taken to mean within 8 hours of presentation. In those patients with massive/aggressive bleeding, the decision whether to proceed directly to angiography will depend on local experience and expertise with this procedure. If bleeding clearly ceases, then expectant colonoscopy (ie, preparation overnight, with colonoscopy the next morning) could also be considered. knew he had a history of hypertension and that his vital signs revealed evidence of orthostasis, resting tachycardia, and, given his baseline hypertension, perhaps outright hypotension, that he had significant bleeding. Additionally, the character of his bleeding was bright red blood per rectum. Thus, we must consider the possibility that he had upper GI bleeding. Nasogastric lavage should be performed; if this reveals blood, then management is dramatically different than if we are dealing with a lower GI tract source. If the nasogastric lavage is negative, an upper GI bleeding source cannot be entirely excluded, but becomes less likely. My own bias is that given the degree of hemodynamic compromise, I would undertake emergent esophagogastroduodenoscopy. If this is negative, then a decision must be made about colonoscopy, and its timing. The character of his bleeding and his response to fluid resuscitation was closely monitored during the first several hours of his hospitalization in the intensive care unit. If, during this monitoring period, it was believed that he had active, ongoing bleeding (particularly that is aggressive), then I advocate angiography. His creatinine level appeared normal (although it was certain that given his age, his creatinine clearance was not normal ) and the risk of contrast nephrotoxicity should be low so long as he was well hydrated. During the initial stabilization and monitoring period, and assuming there is no evidence of an upper GI bleeding source, I would recommend beginning prepa-

6 170 DON C. ROCKEY GASTROENTEROLOGY Vol. 130, No. 1 ration of the colon for colonoscopy as soon as possible. If the effluent clears, my recommendation is for urgent colonoscopy within the next 6 to 8 hours. If, as mentioned previously, the patient is felt to have ongoing aggressive bleeding, angiography should be considered. If bleeding clearly ceases, then expectant colonoscopy (ie, preparation overnight, with colonoscopy the next morning) could also be considered. Once diagnostic testing has been undertaken, specific therapy can be performed. For those undergoing urgent colonoscopy, in whom specific lesions with bleeding stigmata are identified, this generally means endoscopic therapy. Treatment of other disorders (ie, hemorrhoids, various colitides, and others) will depend on the underlying abnormality (see Green et al 30 for review). Conclusion Although acute lower GI bleeding is less common and is usually less hemodynamically significant than upper GI bleeding, it presents unique clinical challenges. The most common cause of significant bleeding is diverticular bleeding; that of intermittent minor hematochezia is hemorrhoidal bleeding. The best diagnostic approach for patients with active bleeding is controversial, but I advocate urgent prepped colonoscopy, except in those patients with massive and aggressive bleeding, in whom angiography should be considered emergently. Recent data suggest that endoscopic therapy may be effective and might improve outcomes. Angiography and surgery play important roles in management of certain patients with lower GI bleeding, emphasizing that successful care of patients with lower GI hemorrhage often requires an integrated multispecialty approach. References 1. Longstreth GF. 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7 January 2006 LOWER GI BLEEDING Angtuaco TL, Reddy SK, Drapkin S, Harrell LE, Howden CW. The utility of urgent colonoscopy in the evaluation of acute lower gastrointestinal tract bleeding: a 2-year experience from a single center. Am J Gastroenterol 2001;96: Green BT, Rockey DC, Portwood G, Tarnasky PR, Guarisco S, Branch MS, Leung J, Jowell P. Urgent colonoscopy for evaluation and management of acute lower gastrointestinal hemorrhage: a randomized controlled trial. Am J Gastroenterol 2005;100: The role of endoscopy in the patient with lower gastrointestinal bleeding. American Society for Gastrointestinal Endoscopy. Gastrointest Endosc 1998;48: Green BT, Rockey DC. Management of lower gastrointestinal hemorrhage. Gastroenterol Clin North Am 2005;34: Bloomfeld RS, Rockey DC, Shetzline MA. Endoscopic therapy of acute diverticular hemorrhage. Am J Gastroenterol 2001;96: Lanthier P, d Harveng B, Vanheuverzwyn R, Debongnie JC, Melange M, Lienard JC, Dive C. Colonic angiodysplasia. Follow-up of patients after endoscopic treatment for bleeding lesions. Dis Colon Rectum 1989;32: Gupta N, Longo WE, Vernava AM. Angiodysplasia of the lower gastrointestinal tract: an entity readily diagnosed by colonoscopy and primarily managed nonoperatively. Dis Colon Rectum 1995; 38: Bemvenuti GA, Julich MM. Ethanolamine injection for sclerotherapy of angiodysplasia of the colon. Endoscopy 1998;30: Zuckerman GR, Prakash C. Acute lower intestinal bleeding. Part I: Clinical presentation and diagnosis. Gastrointest Endosc 1998; 48: Kuo WT, Lee DE, Saad WE, Patel N, Sahler LG, Waldman DL. Superselective microcoil embolization for the treatment of lower gastrointestinal hemorrhage. J Vasc Interv Radiol 2003; 14: Ng DA, Opelka FG, Beck DE, Milburn JM, Witherspoon LR, Hicks TC, Timmcke AE, Gathright JB, Jr. Predictive value of technetium Tc 99m-labeled red blood cell scintigraphy for positive angiogram in massive lower gastrointestinal hemorrhage. Dis Colon Rectum 1997;40: Ledermann HP, Schoch E, Jost R, Decurtins M, Zollikofer CL. Superselective coil embolization in acute gastrointestinal hemorrhage: personal experience in 10 patients and review of the literature [see comments]. J Vasc Interv Radiol 1998;9: Peck DJ, McLoughlin RF, Hughson MN, Rankin RN. Percutaneous embolotherapy of lower gastrointestinal hemorrhage [see comments]. J Vasc Interv Radiol 1998;9: DeBarros J, Rosas L, Cohen J, Vignati P, Sardella W, Hallisey M. The changing paradigm for the treatment of colonic hemorrhage: superselective angiographic embolization. Dis Colon Rectum 2002;45: Junquera F, Quiroga S, Saperas E, Perez-Lafuente M, Videla S, Alvarez-Castells A, Miro JR, Malagelada JR. Accuracy of helical computed tomographic angiography for the diagnosis of colonic angiodysplasia [see comments]. Gastroenterology 2000;119: Ernst O, Bulois P, Saint-Drenant S, Leroy C, Paris JC, Sergent G. Helical CT in acute lower gastrointestinal bleeding. Eur Radiol 2003;13: Jensen DM, Machicado GA. Colonoscopy for diagnosis and treatment of severe lower gastrointestinal bleeding. Routine outcomes and cost analysis. Gastrointest Endosc Clin N Am 1997; 7: Parkes BM, Obeid FN, Sorensen VJ, Horst HM, Fath JJ. The management of massive lower gastrointestinal bleeding. Am Surg 1993;59: Bender JS, Wiencek RG, Bouwman DL. Morbidity and mortality following total abdominal colectomy for massive lower gastrointestinal bleeding. Am Surg 1991;57:536 40; discussion Setya V, Singer JA, Minken SL. Subtotal colectomy as a last resort for unrelenting, unlocalized, lower gastrointestinal hemorrhage: experience with 12 cases. Am Surg 1992;58: Address requests for reprints to: Don C. Rockey, MD, Division of Digestive and Liver Diseases, University of Texas Southwestern Medical Center, 5323 Harry Hines Boulevard, Dallas, Texas don.rockey@utsouthwestern.edu; fax: (214)