Roux-en-Y Gastric Bypass for Clinically Severe Obesity: Normal Appearance and Spectrum of Complications at Imaging 1

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1 Elmar M. Merkle, MD Peter T. Hallowell, MD Cathleen Crouse, RN Dean A. Nakamoto, MD Thomas A. Stellato, MD Published online before print /radiol Radiology 2005; 234: Abbreviations: BMI body mass index GI gastrointestinal RYGB Roux-en-Y gastric bypass 1 From the Department of Radiology, Duke University Medical Center, Erwin Rd, Duke North, Rm 1417, Durham, NC (E.M.M.); and Departments of Surgery (P.T.H., C.C., T.A.S.) and Radiology (D.A.N.), University Hospitals of Cleveland/Case Western Reserve University, Cleveland, Ohio. Received March 3, 2003; revision requested May 23; final revision received January 16, 2004; accepted February 16. Address correspondence to E.M.M. ( elmar.merkle@duke.edu). Authors stated no financial relationship to disclose. RSNA, 2005 Roux-en-Y Gastric Bypass for Clinically Severe Obesity: Normal Appearance and Spectrum of Complications at Imaging 1 Surgery currently appears to be the most effective method to curtail the effects of morbid obesity and all of its comorbid conditions. Although the ideal procedure has yet to be devised, Roux-en-Y gastric bypass has proved to be successful for many morbidly obese patients pursuing weight loss and increased health. As the technical aspects of this procedure become less cumbersome and the patient population increases, it is vital for radiologists to be proficient in the specific evaluation of these patients, in order to provide optimal care. Complications can be minimized, managed more efficiently, or prevented with prompt evaluation by the radiologist. It is important to appreciate the patency of both the gastrojejunostomy and the jejunojejunostomy, as well as adequate progression of contrast material before the patient is discharged (preferably hours after surgery). Follow-up complications include anastomotic leak, staple-line disruption, stomal stenosis, occlusion of the Roux limb, small-bowel obstruction due to adhesions or internal hernia, and obstruction of the enteroenterostomy leading to acute gastric distention. These complications may be life threatening, since clinical symptoms are often inconclusive. To achieve optimal outcome, therefore, conventional radiographic and computed tomographic studies should not be delayed. RSNA, 2005 The World Health Organization has recognized a global epidemic of obesity, which is one of the most alarming health problems not only in the United States but also in the whole Western world (1,2). Despite extended educational measures and increased public awareness, the number of obese individuals continues to increase in industrialized countries. Obesity contributes to at least deaths annually in the United States, and the health care costs of obese American adults amount to approximately $100 billion, which equals approximately 1% of the U.S. gross domestic product. A recent report in the Journal of the American Medical Association (3) indicated that the prevalence of adult obesity increased from 22.9% in the period to 30.5% in Data reflecting the same trend are reported from Europe, as well: The prevalence of obesity in Denmark has increased in men from 10% in 1982 to 13% in 1992 and from 9% to 11% in women during the same period (4). The body mass index (BMI) is currently used as a mathematic calculation to determine if a patient is overweight. The BMI is calculated by dividing a person s body weight in kilograms by their height in meters squared. While the BMI is currently widely accepted as the best way to determine obesity, this number can be misleading in very muscular people or in pregnant or lactating women. The risk for morbidity and mortality accompanying obesity is proportional to the degree of excess weight. By definition, adults with a BMI in the range of kg/m 2 are considered to be of normal weight, while those with a BMI of 25 kg/m 2 or greater are considered to be overweight. Adults with a BMI of 30 kg/m 2 or greater are classified as obese class I; those with a BMI 35 kg/m 2 or greater, as obese class II; and those with a BMI 40 kg/m 2 or greater, as obese class III or extremely obese. The Table shows the continuous 674

2 ESSENTIALS The World Health Organization has recognized a global epidemic of obesity. The majority of American bariatric surgeons prefer a combination of restrictive and malabsorption procedures such as the Roux-en-Y gastric bypass. Complications after Roux-en-Y gastric bypass surgery can be minimized, managed more efficiently, or even prevented with prompt evaluation by the radiologist. increase in the prevalence of overweight, obese, and severely obese American adults over the past 25 years. Alarmingly, the increase in this trend is most pronounced in the younger age groups. Obesity is associated with more than 30 medical conditions, including sleep apnea, hypertension, coronary vascular disease, type 2 diabetes mellitus, degenerative joint and disk disease, and some types of cancer (eg, breast cancer, colorectal cancer) (7). For persons who are overweight or obese, weight loss of as little as 10% can improve some obesity-related conditions, including diabetes and hypertension. Despite important advances in the pharmacologic treatment of obesity, nonsurgical treatment approaches such as diets, behavioral modification, exercise, and pharmacologic agents rarely achieve a greater than 10% weight loss in the majority of obese patients. Low-calorie diets alone have been unsuccessful in achieving permanent weight loss. Therefore, in 1991 the National Institutes of Health Consensus Development Conference on Gastrointestinal Surgery for Severe Obesity stated that gastric restrictive or bypass procedures should be considered (a) for patients with a BMI of greater than 35 kg/m 2 with high-risk comorbidities such as life-threatening cardiopulmonary problems or severe diabetes mellitus and (b) for those with a BMI of greater than 40 kg/m 2 (8). Patients who may be candidates for surgical treatment must demonstrate failure of established nonsurgical weight control programs and must be well informed, motivated, and able to participate in treatment and long-term follow-up. Teams consisting of abdominal surgeons, psychologists, registered dieticians, and registered nurses have been formed throughout the Western world to meet the rising demand for bariatric surgery. Radiologists also play an important role on these teams, because morbidly obese patients are already considered to be high-risk owing to their comorbidities, and clinical examination in these patients may be difficult. Therefore, radiologists must be aware of the common surgical procedures for obesity, the normal imaging appearance after such procedures, and the spectrum of possible complications. SURGICAL TECHNIQUES Surgical procedures for weight reduction can be divided into two major categories: gastric restriction and intestinal malabsorption (7). Restrictive bariatric procedures such as vertical gastric banding and adjustable gastric banding involve the creation of a small neogastric pouch and gastric outlet to decrease food intake. Malabsorption procedures such as jejunoilial bypass, biliopancreatic diversion, or duodenal switch involve a rearrangement of the small intestine to decrease the functional length or efficiency of the intestinal mucosa for nutrient absorption. Roux-en-Y gastric bypass (RYGB) is a combination of both techniques: A small gastric pouch with a small outlet is created, and the functional length of the small bowel is decreased. Data from the 1989 and 1998 membership rosters of the American Society for Bariatric Surgery indicate that 82% of the North American surgeons prefer a combination restrictive-malabsorption procedure such as RYGB, compared with 15% who prefer purely restrictive procedures such as vertical banded gastroplasty, silicone ring gastroplasty, or adjustable gastric banding (9). European surgeons, however, seem to prefer purely restrictive procedures over RYGB. Each procedure has its own assets and drawbacks. While weight loss is, in our opinion, more persistent with RYGB, the major drawback of the procedure is its irreversibility. Gastric banding procedures, on the other hand, are reversible, although in our opinion the weight loss results are not as consistent. It is mandatory for the radiologist involved in bariatric surgery cases to be familiar with the surgical technique used by referring surgeons, since the various procedures have a different appearance on imaging studies and a different spectrum of complications. This review will deal only with the imaging appearance of RYGB and its complications. RYGB was first introduced by Mason and Ito (10) in 1967 for the treatment of morbid obesity. This surgical procedure has had many modifications since its original inception (11). The hallmarks of the procedure are as follows (Fig 1): (a) creation of a small gastric reservoir of ml, which may be stapled in continuity or divided; (b) creation of a small ( 12-mmdiameter) gastrojejunostomy that is either stapled, sutured, or both; and (c) division of the small bowel distal to the ligament of Treitz (suspensory muscle of duodenum). The distal segment is brought up to the pouch to form the Roux limb. This distal segment can be brought up antecolic (ie, anterior to the transverse colon) or retrocolic (ie, posterior to the transverse colon) through an incision in the transverse mesocolon. A short-limb RYGB is less than 100 cm in length and a long-limb bypass is greater than 100 cm. These lengths vary according to surgeon preference and patient size. The Roux limb and biliopancreatic limb (ie, bypassed or defunctionalized stomach, native duodenum, and variable length of in-contiguity proximal jejunum usually 75 cm) are connected by either a stapled or a sutured jejunojejunostomy. These steps can be accomplished both laparoscopically and during laparotomy. PREOPERATIVE IMAGING BEFORE RYGB Other than chest radiographs in two views and an echocardiogram to assess cardiopulmonary function, only one additional imaging study is widely recommended in the preoperative work-up for bariatric surgery: An ultrasonographic (US) study of the right upper quadrant should be performed to rule out cholelithiasis (12,13). In proved cases of cholelithiasis, most surgeons remove the gallbladder at the time of bariatric surgery, because gallstone formation increases during rapid weight loss and endoscopic treatment of choledocholithiasis is technically extremely challenging after RYGB. At present, there is no consensus on whether an upper gastrointestinal (GI) radiographic study should be performed to assess esophageal motility, gastric emptying, the size of a hiatal hernia if present, and the anatomy in patients who have previously undergone gastric surgery. While some bariatric surgeons do not believe routine preoperative radiographic studies are necessary, others consider radiographic studies to be a routine component of the preoperative Volume 234 Number 3 Roux-en-Y Gastric Bypass for Severe Obesity 675

3 Prevalence of Excess Weight among American Adults over Past 25 Years Years Overweight (%) Obese (%) Severely Obese (%) Radiology No data Sources. References 3, 5, 6. Note. Overweight is BMI 25 kg/m 2 ; obese is BMI 30 kg/m 2 ; severely obese is BMI 40 kg/m 2. Figure 2. Upper GI image obtained 1 day after laparoscopic RYGB with megapouch in a 58-year-old woman shows gastric pouch ( ) that is explicitly larger than a lumbar vertebral body. Figure 1. (a) Schematic representation of RYGB with (b) corresponding appearance at upper GI study obtained with water-soluble contrast material. 1 Gastric pouch; 2 staple line; 3 upper side-to-side anastomosis between gastric pouch and Roux limb; 4 defunctionalized stomach; 5 duodenum; 6 pancreaticobiliary limb consisting of the second, third, and fourth portion of the duodenum and variable length of in-contiguity jejunum; 7 blind loop, 8 Roux limb; 9 side-to-side anastomosis between pancreaticobiliary limb and Roux limb. work-up. In the recent literature, we are aware of only one article that addresses this issue: Frigg et al (14) reported their preoperative radiologic and endoscopic evaluation performed prior to laparoscopic adjustable gastric banding. Of 147 upper GI series, 74 (50%) showed hiatal hernias, two (1%) showed motility disorders of the esophagus, and one ( 1%) showed incomplete malrotation. In fewer than 50% of the patients, no pathologic condition was found. Their results seem to support the need for a preoperative GI radiographic study, particularly if a laparoscopic approach is planned, because anatomic orientation may be confusing when viewed through a laparoscope (14). An active peptic ulcer is an absolute contraindication for bariatric surgery (13). Unfortunately, preoperative upper GI studies with contrast material have demonstrated a high false-negative rate for the diagnosis of peptic ulcer. Frigg et al (14), using gastroscopy, found gastritis or duodenitis in 10 of 104 patients, an ulcer in one patient, and erosions in two patients. These findings were not identified on upper GI series. Many institutions currently screen patients for Helicobacter pylori (13). If patients test positive for H pylori, a 2-week course of antibiotics and histamine-2 receptor blockers is prescribed. NORMAL IMAGING APPEARANCE AFTER RYGB Patients in our bariatric program usually undergo an upper GI study within the Figure 3. Upper GI image obtained 1 day after laparoscopic RYGB in a 32-year-old woman shows gastric pouch (black arrow) that is explicitly smaller than a lumbar vertebral body. Defunctionalized stomach and duodenum are not opacified with contrast material, although stomach is outlined with residual air in the fundus ( ) and antrum (white arrows). The blind loop (arrowhead) may be misconstrued as the gastric pouch. first 48 hours after RYGB to rule out an anastomotic leak (Fig 1). After scout image acquisition, the patient is asked to swallow a small sip of a water-soluble contrast agent, which may remain in the distal esophagus and gastric pouch for a variable period (seconds to minutes) before passing the side-to-side anastomosis and filling the blind loop and Roux limb (ie, enteric, or efferent, limb). Delayed pouch emptying may be misconstrued as an anastomotic stenosis, but in the majority of cases it simply reflects a swollen anastomosis after surgery. 676 Radiology March 2005 Merkle et al

4 Figure 4. Images obtained 2 days after RYGB in a 52-year-old woman. (a) Scout radiograph shows staple line (arrow) and nasogastric tube. (b) Upper GI image shows nasograstric tube in place. (c) On upper GI image obtained after removal of the tube, an anastomotic leak (arrow) is evident. A gastric pouch volume of approximately 30 ml and a 12-mm-diameter outlet stoma exhibit the best results. On conventional radiographs, it is hardly possible for the radiologist to quantify the volume of the gastric pouch. As a rule of thumb, however, the gastric pouch should be of a size similar to that of a lower thoracic or lumbar vertebral body (Fig 1). This comparison allows fast and reliable detection of a pouch that is either too large or extremely small (Figs 2, 3). The distal side-to-side anastomosis is difficult to visualize because contrast material rarely refluxes from the jejunum into the pancreaticobiliary limb (15). Similarly, the duodenum and the defunctionalized stomach are difficult to visualize unless they are outlined with gas (Fig 3). In cases of open RYGB surgery, a nasogastric tube is often placed with its distal end in the Roux limb to temporarily provide a stent for the side-to-side anastomosis. In these cases, it is mandatory to repeat the upper GI study after removal of the nasogastric tube, because the tube may obscure an anastomotic leak (Fig 4). In our current practice, we do not use a guidewire to maintain easy access to the jejunum. However, in patients with a high clinical suspicion for an anastomotic leak (that has not been detected prior to removal of the nasogastric tube), the insertion of a guidewire may be helpful before the nasogastric tube is removed. This approach may avoid potential injury in these immediately postoperative patients if an anastomotic leak is detected after removal of the nasogastric tube, necessitating reinsertion of the nasogastric tube. In technical terms, examinations of severely obese patients are difficult because of patient size. Technical problems include difficulty in positioning of patients for optimal radiographs, inability to place the image intensifier over the patient, extreme difficulty during fluoroscopy in depicting intraabdominal structures, and suboptimal radiographs caused by markedly scattered radiation (12). If water-soluble contrast material enhanced radiographs are inadequate, a repeat study with barium contrast material may be helpful. Helical computed tomography (CT) offers a detailed view of the anatomy after RYGB, with all important structures clearly depicted (Fig 5). Currently, no data are available regarding the optimal administration of oral contrast agents. After approval by the referring physician, we administer a 2% dilution of diatrizoate meglumine (Gastrografin; Bracco Diagnostics, Princeton, NJ) 1 hour prior to the CT scan, encouraging the patient to drink as much of the solution as possible immediately prior to the CT examination. Since an anastomotic leak is often a differential consideration, we avoid using barium as an oral contrast agent and do not use effervescent crystals. The gastric pouch may be found by following the course of the distal esophagus. It is usually positioned right laterally to the right of the proximal anastomosis. A normal gastric pouch is usually collapsed at the time of CT. The blind loop and the Roux limb are usually seen, as well. Both structures should not be larger than 2.5 cm in diameter. Whereas the blind loop ends after several centimeters (depending on the surgeon s technique), the Roux limb can usually be followed either retrocolically or antecolically to the distal anastomosis with the pancreaticobiliary limb. The defunctionalized stomach may contain a small amount of air and fluid, but it should never be distended. The native duodenum and the proximal jejunum (part of the pancreaticobiliary limb) can also be followed to the lower anastomosis. These bowel loops should not be larger than 2.5 cm in diameter. Despite the substantial advantages of CT over upper GI series, the routine use of CT in the immediate postoperative course after RYGB is not recommended because of the increased radiation exposure to the patient and the increased cost; Volume 234 Number 3 Roux-en-Y Gastric Bypass for Severe Obesity 677

5 ing position or moved to our angiography suite, which is equipped with an Axiom Artis system (Siemens Medical Systems, Malvern, Pa), which has a table weight limit of 200 kg. As mentioned earlier, the distance between the fluoroscopic table and the image intensifier is also of concern. While our Toshiba systems in the GI radiology suite allow a maximum patient size (in the anteroposterior dimension) of 47 cm, our Siemens angiography system offers a maximum distance of 60 cm between the fluoroscopic table and the image intensifier. Patient dimensions also frequently exceed the size and weight limits of CT systems. Our current CT system (MX8000; Philips Medical Systems, Best, the Netherlands) has a manufacturer-recommended table weight limit of kg. A rigid table weight limit, however, falls short of addressing the problem appropriately, since the patient s weight also needs to be spread over the CT table. It is obvious that a patient with a height of 1.6 m and a weight of 160 kg will strain the table more than will a 1.9-m-tall patient with the identical weight. A reasonable approach for the future may be to encourage the manufacturers to shift from a rigid table weight limit to a BMI limit, which would take patient s height and weight into account. The CT gantry may also be the limiting factor; our current CT system has a maximum size of 68 cm in the right-to-left dimension and 56 cm in the anteroposterior dimension. Patient weight also has a profound effect on the magnitude of intravenous contrast material enhancement both in the vascular system and in parenchymal organs such as the liver. Whereas the total dose of iodine (as determined by the volume and concentration of contrast material) correlates directly with the magnitude of hepatic enhancement, patient weight is inversely related (16). GENERAL AND SPECIFIC COMPLICATIONS AFTER RYGB Figure 5. Transverse contrast material enhanced CT scans in a 51-year-old woman 3 months after RYGB. Patient presented with crampy abdominal pain after eating, but CT findings are unremarkable. (a) CT scan through upper abdomen shows staple line (white arrowhead) between gastric pouch (black arrowhead) and defunctionalized stomach ( ). Side-to-side anastomosis (black arrow) between Roux limb (white arrow) and gastric pouch is positioned anterior to the staple line (white arrowhead). Of note is a small air bubble in the defunctionalized stomach; this is a normal finding after RYGB. Curved arrow blind loop. (b) CT scan obtained 2 cm caudal to a shows Roux limb (straight arrow), end of the blind loop (curved arrow), and defunctionalized stomach ( ). (c) CT scan at level of the transverse mesocolon shows retrocolic Roux limb (arrow), transverse colon, and lower side-to-side anastomosis (arrowhead). (d) CT scan obtained 3 cm caudal to c shows decompressed horizontal duodenum ( ), which is part of the pancreaticobiliary limb. therefore, we believe helical CT should be used only in ambiguous cases where conventional radiographic studies are indeterminate for example, as a follow-up study after a small anastomotic leak. EQUIPMENT-RELATED OBSTACLES IN BARIATRIC PATIENT IMAGING Our GI radiology suite is currently equipped with Fluorex Efficiency 450D systems (Toshiba Medical Systems, Tustin, Calif). These systems have a weight limit of 150 kg. If bariatric patients exceed this limit, they are either examined in a stand- Severely obese patients are already considered to be at high risk because of their comorbidities. Because most of the surgical procedures for obesity are completely elective, prospective patients need to be aware of the possible complications, which can be divided into general and specific categories. General Complications Pulmonary embolism. Pulmonary embolism is the leading cause of perioperative death in patients who undergo bariatric surgery, but it can occur as many as 6 months after the procedure (17). The overall incidence of deep vein thrombosis and pulmonary embolism is reported to be less than 2% (9,11,13,17); however, nearly one-third of the bariatric surgery patients who have pulmonary embolism will die. Several factors increase the possibility of deep vein thrombosis and/or pulmonary embolism in these patients. Morbidly obese patients are less active and may be confined to a bed or chair. Venous stasis disease and polycythemia due to underlying respiratory insufficiency 678 Radiology March 2005 Merkle et al

6 Figure 6. Transverse contrast-enhanced CT scan obtained 20 days after revision of previous RYGB in a 40-year-old-woman shows large fluid collection in the left upper quadrant (arrowheads). Note also small seroma (arrow) in the subcutaneous fatty layer, which had resolved at follow-up imaging (not shown). CTguided biopsy revealed an abscess, which was subsequently drained. are also common in these patients. The combination of some or all of these factors, in addition to the patient undergoing an abdominal surgical procedure in the supine position for several hours, leads to the development of deep vein thrombosis and pulmonary embolism (9). Various prophylactic methods have been employed to prevent deep vein thrombosis and pulmonary embolism, including subcutaneous low-dose anticoagulant injections, pneumatic compression stockings, elastic stockings or bandages, intravenous low-molecular-weight dextran injections, and use of the Trendelenburg position during surgery (13). Unfortunately, none of these methods has been proved to decrease the incidence of postoperative venous thromboembolism in bariatric patients. In our opinion, early postoperative ambulation may be the most important method to prevent postoperative deep vein thrombosis and pulmonary embolism. The diagnosis of deep vein thrombosis and pulmonary embolism at clinical examination can be difficult. In our opinion, color Doppler US is the imaging modality of choice for the work-up of bariatric surgery patients suspected of having lower-extremity deep vein thrombosis, and contrast-enhanced helical CT is the imaging modality of choice for the work-up of those suspected of having pulmonary embolism. If pulmonary CT cannot be performed because of weight Figure 7. Transverse unenhanced CT scans obtained 3 days after RYGB in a 51-year-old woman with stenosis of the enteroenteric anastomosis leading to acute gastric distention. (a) Staple line (arrow), blind loop ( ), and Roux limb (arrowhead) are shown. Note also marked distention of fundus of the defunctionalized stomach. (b) Antegastric Roux limb (arrowhead) and distention of defunctionalized stomach and duodenal bulb ( ) as part of the pancreatobiliary limb are shown. (c) Descending part of the duodenum ( ) and proximal jejunum (straight arrow) as parts of the pancreatobiliary limb, both markedly dilated, are shown. Note also side-to-side enteroenteric anastomosis (curved arrows) and Roux limb (arrowhead). (d) The horizontal part of the duodenum ( ) as part of the pancreatobiliary limb is markedly dilated. constraints, ventilation-perfusion scintigraphy may serve as an alternative imaging modality. To the best of our knowledge, no studies have been performed to compare the diagnostic utility of helical pulmonary CT and ventilation-perfusion scintigraphy in bariatric surgery patients suspected of having pulmonary embolism. Incisional hernia. One of the major advantages of laparoscopic procedures for obesity is the lack of associated incisional hernias, which occur in approximately 5% of cases after open RYGB surgery (11). In general, the diagnosis of an incisional hernia at clinical examination is easy, and no additional imaging studies are required. Gallstone formation. Gallstone formation is increased during rapid weight loss caused by either dietary methods or bariatric surgery. Because most surgeons remove the gallbladder during bariatric surgery in proved cases of cholelithiasis, the incidence of cholelithiasis is approximately 1% 3% after RYGB (11,17,18). US is the imaging modality of choice for patients suspected of having cholelithiasis. Since endoscopic retrograde cholangiography is technically challenging after RYGB, magnetic resonance (MR) cholangiography may be performed in patients suspected of having choledocholithiasis. However, as mentioned earlier, the weight limit of the MR imager table may be an insurmountable obstacle that could prevent bariatric surgery patients from undergoing MR cholangiography. Major wound infection and seroma. Major wound infection after RYGB is seen in Volume 234 Number 3 Roux-en-Y Gastric Bypass for Severe Obesity 679

7 Figure 8. Upper GI studies obtained 18 months after RYGB in a 53-year-old woman in whom gastric staple-line disruption occurred. After initial weight loss, the patient lost the sensation of early satiety and regained weight. (a) Gastric pouch (white arrows), Roux limb (arrowhead), previously excluded stomach ( ), and disrupted staple line (black arrow) are visible. (b) Subsequent image obtained within minutes of a shows patency of the Roux limb (arrowheads). Note rugal folds in previously excluded stomach ( ). White arrow gastric pouch. Figure 9. (a c) Images from upper GI series obtained 5 weeks after RYGB in a 44-year-old woman who presented with multiple episodes of nausea and vomiting show distention of gastric pouch ( ) and wedge-shaped tight anastomosis (arrow) that never changes shape or fully distends. Patient subsequently underwent successful endoscopic dilation. up to 10% of patients, while seromas in the subcutaneous fatty layer are more common, with an incidence of up to 40% (13). Although diagnosis of a superficial wound infection at clinical examination is easy, CT is often required to exclude the presence of intraabdominal abscess in patients with fever and wound infection. Abdominal fluid collection, subphrenic abscess, and peritonitis. These conditions occur in fewer than 2% of all bariatric surgery patients. They are considered to be extremely serious complications and may be life threatening in morbidly obese patients (9,18). Clinical signs may be subtle, and diagnosis is often difficult. CT has a critical role in the work-up of bariatric surgery patients suspected of having an abdominal fluid collection, and it should be performed without hesitation since failure to immediately diagnose and treat an abdominal catastrophe almost always leads to severe systemic sepsis, multiple organ failure, and death (9). This is even more true for patients with a history of bariatric surgery because the overall complication rate in these patients is markedly higher (Fig 6). We usually perform these examinations on our interventional CT scanner in stand-by mode, which means that we perform CT-guided aspiration or drainage in the same imaging session if a suspicious abdominal fluid collection has been detected. Procedure-specific Complications Anastomotic or staple-line leak. The incidence of anastomotic or staple-line leaks is reported to be in the range of 1% 4% for patients who have undergone RYGB (Fig 4) (11,13,17 19). Early postoperative leaks are sometimes difficult to recognize because fever and abdominal tenderness are frequently present due to respiratory insufficiency, atelectasis, and postsurgical abdominal pain. Early diagnosis is important, however, owing to the resultant peritonitis and high mortality. Left shoulder pain, tachycardia, and anxiety are early symptoms. Upper GI studies have an important role in the identification of these leaks. Oral contrast material extravasation is usually seen without difficulty. However, it may be challenging to detect the specific site of the leak, since image quality may be limited owing to the patient s body habitus. Notably, the incidence of anastomotic leaks is five to 10 times higher after revision procedures (11,20). Acute gastric distention. Afferent gastric distention (or afferent or closed-loop obstruction) occasionally occurs after open or laparoscopic RYGB because of obstruction or edema at the enteroenterostomy site (9). The distention may be severe enough to cause a staple-line disruption or, if the Roux limb is brought antegastric, put enough tension on the gastrojejunostomy to cause a leak. Patients usually report a bloated feeling and may often hiccup. Abdominal radiographic studies may demonstrate a distended excluded stomach and often show an air-fluid level. In our experience, CT is the imaging modality of choice for patients who may have obstruction of the enteroenterostomy, because all important structures (eg, the defunctionalized stomach, duodenum, pancreaticobiliary limb, and lower side-to-side anastomosis) are well depicted (Fig 7). Typical imaging findings include severe distention of the pancreaticobiliary limb adjacent to the lower anastomosis and variable distention of the duodenum and defunctionalized stomach. Gastric and duodenal distention will become progressively worse over time because pancreaticobiliary fluid will accumulate. Percutaneous fine-needle decompression may be 680 Radiology March 2005 Merkle et al

8 temporarily successful; however, if distention recurs, emergent surgery may be necessary. Staple-line disruption. Staple-line disruption is a complication that can occur in both divided and undivided RYGB procedures. Many cases may be subclinical, and patients may not lose the sensation of early satiety. Surgical correction involves restapling and dividing the stomach. In our opinion, an upper GI series is the imaging modality of choice in cases suspicious for staple-line disruption (Fig 8). The primary imaging finding is detection of oral contrast material that outlines rugal folds in the defunctionalized stomach. As mentioned earlier, it may be challenging to detect the exact location of the staple-line disruption, because image quality may be limited owing to the patient s body habitus. Stomal stenosis. Stomal stenosis is another complication of RYGB (18) (Fig 9). The gastrojejunal stoma is created to be approximately 12 mm in diameter. Patients with stenosis of the gastrojejunal stoma typically present with postprandial epigastric pain and vomiting. While diagnosis and treatment are usually accomplished by means of endoscopy, fluoroscopically guided balloon dilation may serve as an alternative treatment modality. Vance et al (21) performed 41 fluoroscopically guided balloon dilations in 28 patients with symptoms of gastric outlet obstruction after gastric restrictive surgery for morbid obesity. After initial fluoroscopically guided balloon dilation, 11 (39%) of 28 patients remained asymptomatic during at least 3 months of follow-up. Recurrent dysphagia occurred in 17 (61%) patients, who were treated either surgically (n 3), with endoscopically guided balloon dilation (n 4), with fluoroscopically guided balloon dilation (n 9), or medically (n 1). Of the nine patients who underwent a second fluoroscopically guided balloon dilation, two became asymptomatic. The seven patients who remained symptomatic were treated with surgery (n 3), endoscopically guided balloon dilation (n 1), or fluoroscopically guided balloon dilation (n 3). Of the three patients treated with a third fluoroscopically guided balloon dilation, one became asymptomatic. Overall, fluoroscopically guided balloon dilation was effective in 14 (50%) of 28 patients. Stomal ulceration. Patients with stomal ulceration usually present with severe dyspepsia, burning retrosternal pain, and vomiting. Diagnosis is usually made with the aid of endoscopy, because detection Figure 10. Transverse unenhanced CT scans obtained 19 months after RYGB in a 40-year-old woman with internal hernia through the transverse mesocolon. (a) Scan at level of the stomach shows massive gastric distention. Note normal caliber of blind loop (straight arrow) and Roux limb (arrowhead). Curved arrow splenic colonic flexure. (b) Scan above level of the transverse mesocolon shows massive dilatation of duodenum and distention of retrocolic jejunum (large black ) as parts of the pancreaticobiliary limb. Roux limb (arrowhead) is compressed. Note proximal transverse colon (straight arrows), dilated jejunal loop posterior to transverse colon (white ), distal transverse colon (small black ), and descending colon (curved arrow). (c) Scan at level of the transverse mesocolon shows compression of jejunum (straight arrows) as part of the pancreaticobiliary limb. Roux limb (small arrowhead) is barely visible. Note also dilated jejunal loop (white ), hepatic colonic flexure (large arrowhead), distal transverse colon (black ), and descending colon (curved arrow). (d) Scan below level of the transverse mesocolon shows dilated jejunum (large white ) as part of the pancreaticobiliary limb. Note also dilated jejunal loop (small white ), ascending colon (arrowhead), distal transverse colon (black ), and descending colon (curved arrow). of stomal ulceration may be difficult on upper GI radiographic studies and nearly impossible on CT scans (1). Treatment is with proton pump inhibitors and antibiotics if the patient is positive for H pylori. Small-bowel obstruction. This complication occurs within the first several postoperative weeks in 1% 5% of all patients (13,18,22) and is usually caused by postoperative adhesions after open RYGB. While the prevalence of these adhesions has been reduced by using a laparoscopic approach, the incidence of internal hernias has increased a complication that appears to be more common with a laparoscopic approach. Patients may present with nonspecific symptoms of crampy abdominal pain. Vomiting is frequently absent, because few gastric or enteral secretions accumulate from the gastric pouch or Roux limb. Internal hernias can develop in the transverse mesocolon, where the limb passes through (most common type) or around (Petersen hernia) the mesentery of the Roux limb, or in the mesenteric defect at the enteroenterostomy site (15,18,23). The herniated bowel is usually the Roux limb or the pancreaticobiliary limb itself (Figs 10, 11). It is difficult to distinguish small-bowel obstruction caused by adhesions from that caused by internal hernia on the basis of findings from CT, upper GI series, or both. Blachar et al (18) reported on 15 patients with bowel obstruction following laparoscopic RYGB surgery. Nine patients had an internal Volume 234 Number 3 Roux-en-Y Gastric Bypass for Severe Obesity 681

9 Figure 11. Images obtained 2 months after RYGB in a 58-year-old woman with internal hernia through a small-bowel mesenteric defect at jejunojejunostomy site. (a) Upper GI image shows normal-sized small gastric pouch (straight arrow) and distended blind loop ( ) and Roux limb (arrowheads). (b) Transverse contrast-enhanced CT scan obtained 2 cm caudal to gastrojejunostomy shows collapsed defunctionalized stomach ( ), dilated blind loop (straight arrow), and dilated Roux limb (arrowhead). (c) Transverse contrast-enhanced CT scan at level of the jejunojenunostomy shows dilated Roux limb (large arrowheads) and hernia (straight arrow) at jejunojejunostomy. Note also decompressed ileal loop (small arrowheads) and transverse and descending colon (curved arrows). Figure 12. Radiographs in a 22-year-old woman who presented 4 days after RYGB with nausea and vomiting caused by small-bowel obstruction at level of the transverse mesocolon due to tight mesocolic incision. (a) Unremarkable scout radiograph shows staple line and nasogastric tube. (b) Contrast-enhanced image from upper GI series demonstrates filling of pouch (arrow), blind loop (arrowhead), and Roux limb ( ). (c) Delayed image acquired 2 days after contrast material ingestion shows marked dilatation of pouch (arrow), blind loop (arrowhead), and Roux limb ( ), with no contrast material passing the level of the transverse mesocolon. Surgery revealed small-bowel obstruction at level of the transverse mesocolon due to tight mesocolic incision. hernia, while the remaining six had bowel obstruction caused by adhesions. At upper GI series, six (67%) of nine internal hernias and two (33%) of six adhesions were correctly diagnosed (18). Two internal hernias were misdiagnosed as adhesions, and one adhesion was misdiagnosed as an internal hernia. The remaining four cases were considered equivocal. An abnormal cluster of dilated bowel segments in the left upper quadrant or midline was the best imaging finding to help distinguish between internal hernia and adhesions. This specific finding was present in 89% of patients with internal hernia and in 33% of those with adhesions. At present, knowledge regarding the CT appearance of internal hernia following RYGB is limited. Blachar et al (18) reported the largest series of which we are aware a total of three cases: one through a rent in the transverse mesocolon, one through a rent in the small-bowel mesentery, and one Petersen type. In the same series, one case of small-bowel obstruction due to adhesions was identified. While distended small-bowel segments ( 2.5-cm diameter) with a transition point from dilated to nondilated small bowel were seen in all four cases, the mesenteric vessels were engorged and stretched only in the cases of internal hernia. In that series, the Petersen hernia was misdiagnosed at CT as adhesions, while the other two internal hernias were correctly diagnosed. Regardless of the underlying cause of the small-bowel obstruction, expedient surgical treatment is mandatory. Occlusion of Roux limb. Another type of small-bowel obstruction is the occlusion of the Roux limb at the level of the transverse mesocolon, because in RYGB most 682 Radiology March 2005 Merkle et al

10 of the Roux limbs are positioned posterior to the transverse colon (Fig 5). Occlusion of the Roux limb occurs in 1% of patients (17) and is easily diagnosed on an upper GI series (Fig 12). INTERVENTIONAL MANAGEMENT OF COMPLICATIONS A number of the possible complications in bariatric surgery patients can be successfully managed with interventional radiologic techniques. This spectrum ranges from simple aspiration and drainage of abdominal fluid collections (Fig 13) to emergent CT-guided gastrostomy (of the excluded or bypassed stomach) for temporary decompression in cases of acute gastric distention caused by obstruction of the enteroenterostomy. Furthermore, duodenal or jejunal feeding tubes may be placed with CT guidance in cases of gastrojejunal anastomotic complications, in order to avoid prolonged intravenous nutrition (Fig 14). Finally, stenoses of the gastrojejunal anastomosis can be dilated with the aid of fluoroscopic guidance (21). Figure 13. Transverse unenhanced CT scans in a 40-year-old woman who presented 1 month after revision of previous RYGB with persistent fluid collection in left upper quadrant, which required image-guided drainage. (a) An 18-gauge Yueh needle is visible within fluid collection in left upper quadrant. Aspiration revealed purulent fluid. (b) A 12-F drainage catheter is visible within fluid collection, which subsequently resolved. References 1. Stellato TA, Crouse C, Hallowell PT. Bariatric surgery: creating new challenges for the endoscopist. Gastrointest Endosc 2003; 57: Martin LF, Hunter SM, Lauve RM, O Leary JP. Severe obesity: expensive to society, frustrating to treat, but important to confront. South Med J 1995; 88: Flegal KM, Carroll MD, Ogden CL, Johnson CL. Prevalence and trends in obesity among US adults, JAMA 2002; 288: Heitmann BL. Ten-year trends in overweight and obesity among Danish men and women aged years. Int J Obes Relat Metab Disord 2000; 24: Mokdad AH, Serdula MK, Dietz WH, Bowman BA, Marks JS, Koplan JP. The spread of the obesity epidemic in the United States, JAMA 1999; 282: Popkin BM, Udry JR. Adolescent obesity increases significantly in second and third generation U.S. immigrants: the National Longitudinal Study of Adolescent Health. J Nutr 1998; 128: Mun EC, Blackburn GL, Matthews JB. Current status of medical and surgical therapy for obesity. Gastroenterology 2001; 120: Gastrointestinal surgery for severe obesity: National Institutes of Health Consensus Development Conference statement. Am J Clin Nutr 1992; 55(suppl 2):615S 619S. 9. Byrne TK. Complications of surgery for obesity. Surg Clin North Am 2001; 81: , vii viii. 10. Mason EE, Ito C. Gastric bypass in obesity. Surg Clin North Am 1967; 47: Fobi MA, Lee H, Holness R, Cabinda D. Gastric bypass operation for obesity. World J Surg 1998; 22: Figure 14. Images obtained 6 months after RYGB in a 58-year-old woman who had several episodes of dehydration and was presenting with nausea and vomiting that required imageguided placement of a feeding tube. (a) Transverse unenhanced CT scan shows tip of 18-gauge Yueh needle in duodenal bulb. (b) Fluoroscopic image shows diluted contrast material in duodenum ( ), which confirmed correct position of feeding tube. 12. Bova JG, Robinson JR, McFee AS. Radiologic evaluation before gastric bypass for morbid obesity. Am J Surg 1984; 147: Brolin RE. Gastric bypass. Surg Clin North Am 2001; 81: Frigg A, Peterli R, Zynamon A, Lang C, Tondelli P. Radiologic and endoscopic evaluation for laparoscopic adjustable gastric banding: preoperative and follow-up. Obes Surg 2001; 11: Blachar A, Federle MP. Gastrointestinal complications of laparoscopic Roux-en-Y gastric bypass surgery in patients who are morbidly obese: findings on radiography and CT. AJR Am J Roentgenol 2002; 179: Heiken JP, Brink JA, McClennan BL, Sagel SS, Crowe TM, Gaines MV. Dynamic incremental CT: effect of volume and concentration of contrast material and patient weight on hepatic enhancement. Radiology 1995; 195: Higa KD, Boone KB, Ho T. Complications of the laparoscopic Roux-en-Y gastric bypass: 1,040 patients what have we learned? Obes Surg 2000; 10: Blachar A, Federle MP, Pealer KM, Ikramuddin S, Schauer PR. Gastrointestinal complications of laparoscopic Roux-en-Y gastric bypass surgery: clinical and imaging findings. Radiology 2002; 223: Toppino M, Cesarini F, Comba A, et al. The role of early radiological studies after gastric bariatric surgery. Obes Surg 2001; 11: Cariani S, Nottola D, Grani S, Vittimberga G, Lucchi A, Amenta E. Complications after gastroplasty and gastric bypass as a primary operation and as a reoperation. Obes Surg 2001; 11: Vance PL, de Lange EE, Shaffer HA Jr, Schirmer B. Gastric outlet obstruction following surgery for morbid obesity: efficacy of fluoroscopically guided balloon dilation. Radiology 2002; 222: Filip JE, Mattar SG, Bowers SP, Smith CD. Internal hernia formation after laparoscopic Roux-en-Y gastric bypass for morbid obesity. Am Surg 2002; 68: Blachar A, Federle MP, Dodson SF. Internal hernia: clinical and imaging findings in 17 patients with emphasis on CT criteria. Radiology 2001; 218: Volume 234 Number 3 Roux-en-Y Gastric Bypass for Severe Obesity 683