Obesity is an increasingly prevalent health problem in

Transcription

1 Imaging After Bariatric Surgery for Morbid Obesity: Roux-en-Y Gastric Bypass and Laparoscopic Adjustable Gastric Banding Laura R. Carucci, MD, and Mary Ann Turner, MD Obesity is an increasingly prevalent health problem in Western countries. Up to two-thirds of the US population is overweight or obese, as defined by a body mass index (BMI) 25 kg/m 2. 1 Between1986 and 2000, the prevalence of obesity (BMI 30 kg/m 2 ) has doubled and morbid obesity (BMI 40 kg/m 2 ) has quadrupled, resulting in 5%-7% of US adults being considered morbidly obese. 1,2 Nonsurgical approaches for morbid obesity have had limited long-term success, and bariatric surgery has been shown to be a more effective treatment in terms of sustained weight loss, decreased morbidity, reversal of comorbidities, and prolonged life expectancy. 3-5 Bariatric surgery may be considered for patients who have failed conservative treatment with a BMI of 40 kg/m 2 or a BMI of 35 kg/m 2 with associated highrisk, obesity-related comorbidities. 1,3,4 Roux-en-Y gastric bypass (RYGB) is the most commonly performed bariatric procedure in the United States, constituting an estimated 88% of procedures in ,6 The highest long-term success rates have been demonstrated with RYGB in comparison with other surgical weight loss procedures, and RYGB is considered by many the bariatric procedure of choice in the United States. 3,5,7-10 Laparoscopic adjustable gastric banding (LAGB) represents 10% of US bariatric procedures. 11 Although LAGB has gained popularity worldwide since the early 1990s and is the leading procedure performed internationally, the Food and Drug Administration did not approve the first adjustable gastric band for use in the United States until 2001 (LAP-BAND, Allergan, Irvine, CA formerly INAMED Health and BioEnterics Corporation). 12,13 Given relative ease of placement, LAGB is becoming a more popular treatment option and has replaced other restrictive procedures, such as vertical banded gastroplasty in the United States. Department of Radiology, Abdominal Imaging Section, Virginia Commonwealth University Medical Center, Richmond, VA. Address reprint requests to Laura R. Carucci, MD, VCU Medical Center, 1250 E Marshall St, Main Hospital, 3rd Floor, Rm 3-417, PO Box , Richmond, VA Lcarucci@vcu.edu This article will address the 2 most popular bariatric procedures currently performed in the United States: RYGB and LAGB. Despite the success of RYGB and LAGB, many complications may occur and are often diagnosed with imaging. It is important for radiologists to recognize the expected postoperative anatomy on fluoroscopic and computed tomography (CT) examinations as well as potential complications. Roux-en-Y Gastric Bypass With RYGB, a small gastric pouch is created to exclude the remainder of the stomach, duodenum, and proximal jejunum from the path of food. The gastric pouch is anastomosed to a Roux jejunal limb through a small stoma. The Roux limb typically has a short, blind-ending limb and an antegradeflowing limb. The Roux limb may be brought to the gastric pouch through a defect in the transverse mesocolon (retrocolic) or anterior to the transverse mesocolon (antecolic). There is a jejunojejunal (JJ) anastomosis between the antegrade-flowing jejunal limb and the excluded jejunal limb followed by a common channel (Fig. 1). Ingested contents are expected to flow from the esophagus into the small gastric pouch, through a narrow stoma and into the Roux limb. RYGB results in weight loss because of early and prolonged satiety from the small pouch and narrow stoma (restrictive), as well as a malabsorptive component because of the bypassed proximal jejunum. 5,14,15 Upper Gastrointestinal Examination Technique and Expected Findings After RYGB RYGB patients are often evaluated with upper gastrointestinal (UGI) and small bowel follow-through examinations. Knowledge of expected postoperative anatomy and thorough fluoroscopic evaluation is essential for proper diagnosis. Radiologic evaluation in the early postoperative period is helpful, as clinical evaluation may be difficult in this patient population. Early postoperatively, UGI may be carried out to assess for leak, edema, ileus, and obstruction. Patients are evaluated X/09/$-see front matter 2009 Elsevier Inc. All rights reserved. doi: /j.ro

2 284 L.R. Carucci and M.A. Turner Figure 1 RYGB: Expected postoperative anatomy. (A) Diagram depicting RYGB anatomy with a small gastric pouch (P) anastomosed to a Roux limb with a narrow stoma (arrow). The remainder of the stomach, duodenum, and proximal jejunum are excluded from the path of food (excluded limb). There is then a small bowel anastomosis (arrowhead). (B) UGI spot image in the LPO position shows the gastric pouch, stoma (arrow), and proximal Roux limb. P, gastric pouch; BL, blind-ending limb; J, jejunum; EL, excluded Limb. initially using oral water-soluble contrast material. If no leak is identified, barium may be administered to assess for more subtle leaks. After a preliminary radiograph, the patient is placed in the supine left posterior oblique (LPO) position and contrast material is administered under fluoroscopy. The LPO position allows for optimal assessment of the gastrojejunal (GJ) anastomosis. Attention is initially directed toward the postsurgical area in the left upper quadrant, including the pouch, stoma, and jejunal limb (Fig. 1). Adequate distension of the pouch and stoma are essential to properly assess for leak. 16 Additional fluoroscopic views are obtained as indicated, and overhead radiographs are obtained until contrast material passes the JJ anastomosis, as obstruction and rarely leak may occur at this site. Late postoperative UGI may be carried out for abdominal pain, obstruction, internal or ventral hernia, failed weight loss, or weight gain. The examination is performed similarly; however, only oral barium is administered. The study is conducted until the terminal ileum is opacified, as obstruction or internal hernia (IH) may not become apparent until the entire small bowel is opacified. Computed Tomography After RYGB Radiologists must be also aware of the expected RYGB anatomy on CT to accurately diagnose potential complications. Complications, such as IH and patterns of obstruction relative to the altered gastrointestinal anatomy, may be difficult to recognize after RYGB. It is important to properly identify the gastric pouch, excluded stomach, Roux limb, and JJ anastomosis on CT, and to attempt to track the small bowel throughout its course (Fig. 2). Complications After RYGB Despite the success of RYGB, many serious complications may occur (Table 1). Complications may be divided into early ( 1 month) and late ( 1 month) postoperative complications; however, many can occur at any time after RYGB. Postoperative Leak Postoperative leak is the most common serious early complication of RYGB occurring in up to 6% of patients. 7,9,16,17 Leak is most often diagnosed within 10 days after surgery, with 77% diagnosed in the first week. 16 Early recognition and treatment are imperative, as leak may result in increased morbidity and mortality after RYGB, and additional surgery is required in up to 80% of patients. 14,16,17 Radiologic contrast studies are often essential to diagnose postoperative leak, and routine early postoperative UGI may help to promptly recognize leak and minimize the associated morbidity. 15,16,18 Most postoperative leaks (77%) arise from the GJ anastomosis (Fig. 3). Leaks may arise from the distal esophagus, gastric pouch, blind-ending jejunal limb, or rarely the JJ anastomosis. 16 Most leaks (75%) extend to the left of the stoma, with 62% resulting in left upper quadrant fluid collections that can be seen on UGI or CT 16,18 (Fig. 3). In some cases, leak may only be identified by visualization of contrast material entering a surgical drain, often best seen on an overhead radiograph. Pitfalls that may mimic free leak on UGI include plication defects, retrograde flow into the excluded stomach, and leak into the excluded stomach.18,19 A plication defect is a focal out-pouching associated with suture lines along the gastric pouch or GJ anastomosis (Fig. 4). As compared with a small

3 Imaging after bariatric surgery for morbid obesity 285 Figure 2 RYGB: Postoperative anatomy on CT. (A) Contrast-enhanced axial CT image shows the gastric pouch (arrowhead), gastric staple line (arrow), and excluded stomach (ES). (B) Axial CT image slightly more caudally shows the distal ES and Roux limb (arrow). (C) Axial CT image in the mid abdomen shows the JJ anastomosis (arrowheads). leak, a plication defect will readily fill and empty with contrast material and will have well-defined margins. Contrast material near the GJ stoma on UGI may be located in the excluded stomach and could appear similar to free leak. This can occur through retrograde flow, most often as a delayed finding, with ileus or obstruction (Fig. 5). No contrast material is seen near the anastomosis at initial fluoroscopy. Contrast material may also enter the excluded stomach at initial fluoroscopy through a leak across the gastric staple line (staple line disruption or gastrogastric fistula) (Fig. 6). Intragastric location may be confirmed by rotating the patient to the Table 1 Complications After RYGB Early (< 1 mo) Postoperative leak Stomal edema and/or hematoma Ileus Obstruction Staple line disruption Gastrogastric fistula Acute distention of the excluded stomach Late (> 1 mo) Staple line dehiscence Stomal stenosis Obstruction Internal hernia Abdominal wall hernia Intussusception Marginal ulcers right to opacify the more distal stomach and duodenum. 18,19 On CT, the excluded stomach could be mistaken for fluid collection or abscess if not properly identified. Communication With the Excluded Stomach A leak across the gastric staple line into the excluded stomach may be an early or late postoperative complication because of staple line disruption, dehiscence, or gastrogastric fistula. Communication between the gastric pouch and the remainder of the stomach may result in inadequate weight loss, and patients may require nonemergent surgical revision to achieve a more optimal outcome. 18,19 Communication with the excluded stomach has an incidence of up to 4%; however, incidence varies with surgical technique, with a decreased incidence after complete transection of the gastric pouch. 8,18-20 Early disruption of the staple line may result from inadequate surgical division of the pouch. Contrast may also enter the excluded stomach as a consequence of free leak or gastrogastric fistula. 15,19 In the late postoperative course, staple line dehiscence is most often due to extensive stretching of the gastric pouch with food. 15,19,20 Communication with the excluded stomach is readily diagnosed with UGI. At fluoroscopy, the excluded stomach is

4 286 L.R. Carucci and M.A. Turner Figure 3 RYGB: Postoperative leak in 3 different patients. (A) UGI spot image shows a leak from the GJ anastomosis (arrow) extending to the left, with a small collection of extraluminal contrast material (L). (B) Supine UGI image shows a postoperative leak with a large left subphrenic collection (L). (C) Axial CT image shows a large left upper quadrant collection (L) of contrast material and gas with an associated left pleural effusion. P, pouch; J, jejunum. opacified with contrast material as contrast exits the gastric pouch (Fig. 6). Depending upon the severity, contrast material may preferentially enter the excluded stomach or the jejunal limb. As described earlier, diagnosis at initial fluoroscopy is important, as later contrast may enter the excluded stomach through retrograde flow. On CT, it is difficult to distinguish contrast material entering the excluded stomach across the staple line from retrograde flow. The presence of contrast material in the excluded fundus and not in the duodenum may suggest communication with the excluded stomach. However, UGI can easily make this distinction. Acute Obstruction After RYGB Early obstruction after RYGB is most often because of postoperative edema and/or hematoma involving the GJ or JJ anastomosis (Fig. 7). With a retrocolic Roux limb, edema and/or hematoma can also occur at the site where the Roux limb crosses the transverse mesocolon (Fig. 7). Narrowing at any of these locations may cause mild to severe obstruction. Acute distention of the excluded stomach may occur because of obstruction with retrograde flow into the excluded limb. This places increased pressure on the gastric staple line and may result in perforation if not treated promptly. Acute gastric distention may be temporarily relieved by percutaneous decompression or gastrostomy catheter placement until edema and/or hematoma resolve. Stomal Stenosis Stomal stenosis may occur at the GJ or JJ anastomosis and is a late complication, with a mean postoperative day of ,22 GJ stomal stenosis occurs in up to 10% of patients and results in dilatation of the pouch and esophagus with delayed emptying. 7,8,21,22 Optimal visualization of the stoma may be difficult because of a superimposed distended pouch. 15 GJ stenosis usually responds well to endoscopic dilatation. 15 JJ stomal stenosis is rare, occurring in 0.9% of patients, and may require surgical revision. 21

5 Imaging after bariatric surgery for morbid obesity 287 thickening. Marginal ulcers decrease in incidence with smaller pouch size and respond well to medical treatment. 15,21 Late Obstruction Small bowel obstruction (SBO) after RYGB occurs in up to 5% of patients with a similar incidence after open and laparoscopic surgery. 2,23,24 Late SBO may be due to adhesions, IH, abdominal wall hernia, and rarely intussusception. After open surgery, adhesions are the most common cause of SBO. With laparoscopic RYGB, IH is more often the cause of SBO. The lack of adhesions after laparoscopic surgery is thought to allow for increased bowel mobility and increased potential for IH. 8,23-26 Figure 4 RYGB: Postoperative plication defect. LPO UGI image shows a small focal outpouching (arrow) extending along the lateral aspect of the gastric pouch (P) consistent with a plication defect. A, gastrojejunal anastomosis. Marginal Ulcers Marginal ulcers occur near the GJ anastomosis in up to 3% of patients because of exposure of the jejunal mucosa to gastric secretions. 8,14 On UGI, this appears as a small focal outpouching, with stasis of contrast material and associated fold Internal Hernia. IH occurs in up to 3% of RYGB patients and is much more common after laparoscopic surgery as compared with open RYGB. 7,8,22,25,27 Although typically a late complication, IH can occur at any time after RYGB. With IH, bowel herniates through a mesenteric defect, most often the transverse mesocolic defect (retrocolic RYGB), the mesenteric defect for the JJ anastomosis, and/or posterior to the Roux limb (Petersen s defect). 21,22,25-28 IH can lead to obstruction, ischemia, infarction, and perforation, and can be a devastating complication of RYGB, especially if diagnosis and treatment are delayed. 8,21,22,25,26 IH is often difficult to diagnose clinically, as symptoms may be intermittent and/or nonspecific A high index of suspicion is necessary for diagnosis and urgent surgery may be performed on the basis of clinical suspicion. The diagnosis of IH is also difficult with UGI and CT, and knowledge of postoperative anatomy and changes of bowel Figure 5 RYGB: Retrograde opacification of the excluded stomach. (A) An overhead radiograph from UGI shows contrast material in the left upper quadrant (arrows) near the GJ anastomosis that could be mistaken for free leak. However, no leak was seen at initial fluoroscopy. The pouch (P) and jejunal limb (J) are dilated. (B) A second radiograph obtained 45 minutes later shows contrast material in the distended excluded stomach (ES) and also in a dilated excluded duodenum (D). The Roux limb remains dilated (J). The excluded stomach is opacified through retrograde flow as a result of obstruction near the small bowel anastomosis, with dilatation of both the Roux limb and the excluded limb.

6 288 L.R. Carucci and M.A. Turner of IH include clustered bowel displacing other bowel, small bowel limbs entering and exiting the clustered segment, and stasis in clustered bowel 22,27 (Fig. 8). There is a change in bowel configuration as compared with a previous study and a visible JJ anastomotic suture line may be displaced, most often into the left upper quadrant. 27 CT also shows clustered bowel in an atypical location. Associated mesenteric changes can be identified, including stretching and/or swirling of vessels with mesenteric engorgement 18,28-30 (Fig. 9). Reported CT findings of IH include small bowel in the left upper quadrant above the transverse mesocolon, cephalad displacement of the JJ anastomosis, clustered blood vessels in the left upper quadrant, and a swirled appearance of mesenteric fat or vessels. 29,30 Figure 6 RYGB: Leak across the staple line into the excluded stomach (staple line disruption).ugi spot image shows contrast material to the left of the GJ anastomosis (arrow) in the excluded stomach (ES). There is also opacification of the jejunal limb (J). P, gastric pouch. configuration are essential to make this diagnosis. On UGI, there is an abnormal bowel configuration with clustered, displaced small bowel loops (Fig. 8). Clustered small bowel is most often in the left abdomen (90%), but can be located anywhere in the abdomen and pelvis. 18,27 Other UGI findings Ventral Hernia. Abdominal wall hernias are much less common after laparoscopic RYGB as compared with open surgery; however, they can occur at any incisional or port site and may often result in SBO and/or bowel strangulation because of small hernia neck size. 7,21 Intussusception. Intussusception after RYGB often occurs near the JJ anastomosis, possibly with the suture line acting as a lead point. This may be transient or fixed and can result in SBO. 18 Patterns of Small Bowel Obstruction. Because of the GI tract alterations with RYGB, there are 3 patterns of SBO that can be seen on UGI or CT, relative to the JJ anastomosis. 18 SBO may result in dilatation of the Roux limb only with the distal small bowel and excluded limb decompressed (Fig. 10). The collapsed excluded stomach and duodenum may cause confu- Figure 7 RYGB: Early obstruction because of edema and/or hematoma in 2 different patients. (A) Spot UGI image shows contrast in a dilated esophagus and gastric pouch (P), with high-grade obstruction at the stoma (arrow) as a result of acute edema. (B) Overhead radiograph from an UGI shows dilatation of the Roux limb (J) because of narrowing where the Roux limb crosses the transverse mesocolon (arrow) and also at the JJ anastomosis (arrowhead). Distal small bowel is decompressed. P, gastric pouch.

7 Imaging after bariatric surgery for morbid obesity 289 Figure 8 RYGB: Internal hernia on UGI. (A) Scout abdominal radiograph shows the GJ (arrowhead) and JJ (arrow) anastomoses. The JJ anastomosis is displaced cephalad from its expected location in the left mid abdomen (arrow). (B) Overhead radiograph from UGI shows clustered small bowel loops in the left mid-abdomen (white arrows), lateral to the descending colon. Bowel limbs can be seen entering and exiting the clustered segment (black arrows). J, jejunal limb. sion on CT, and identification of RYGB anatomy is essential to make the appropriate diagnosis. SBO may result in dilatation of the Roux limb and excluded limb (through retrograde flow) with decompressed distal small bowel (Fig. 5). SBO may result in dilatation of only the excluded limb. This results in increased pressure in the excluded stomach and can cause perforation if not recognized and treated promptly. On UGI, a dilated excluded stomach exerts mass effect on the opacified, decompressed Roux limb. On CT, the excluded stomach is dilated and fluid-filled, and recognition of the decompressed Roux limb is necessary to make this important diagnosis (Fig. 11). Percutaneous gastric decompression may be necessary. Laparoscopic Adjustable Gastric Banding Gastric banding is a restrictive procedure that limits the volume of food that can be consumed. 31 A gastric band procedure was first introduced by Kuzmak in 1986 and was made available laparoscopically in the early 1990s The first adjustable gastric band was approved for use in the United States by the Food and Drug Administration in Since that time, additional versions of the band have been approved and the concept of a reversible, adjustable gastric band is an increasing popular treatment option for morbid obesity in the United States. 31,35 Figure 9 RYGB: Internal hernia on CT. (A) Axial contrast-enhanced CT image shows opacified small bowel loops displaced cephalad above the gastric pouch (P) and excluded stomach (ES). (B) Axial CT image slightly more caudally shows a swirling appearance of the mesenteric vasculature (arrows) with mild mesenteric edema.

8 290 L.R. Carucci and M.A. Turner loss with improved comorbidities and has less morbidity than RYGB. 31,36,37,39 With LAGB, a silicone band is placed around the upper stomach to create a small gastric pouch and a narrow stoma to communicate with the remainder of the stomach 32,36,41 (Fig. 12). This limits food intake and slows emptying. The angle of the long axis of the band with the vertical ( angle) should be 4-58 in the anteroposterior projection. 2,41 The band has an inflatable inner cuff that is connected through tubing to a subcutaneous port sutured to the anterior rectus sheath (Fig. 12). This allows for percutaneous adjustment of the band according to the patient s weight loss curve. The stomal diameter may be adjusted by injecting the port with fluid to inflate the cuff (narrow the stoma), or by aspirating fluid from the port to deflate the cuff (widen the stoma). 32,34,35 Figure 10 RYGB: Small bowel obstruction with a dilated Roux limb. Overhead radiograph from UGI shows dilatation of the gastric pouch (P) and Roux limb (J) with a focal, abrupt, transition point at the JJ anastomosis (arrow). Distal bowel and the excluded limb are decompressed. LAGB is the least invasive bariatric procedure and it involves no cutting, stapling, or bypassing portions of the gastrointestinal tract. 13,32,36,37 It is reversible and can adjust to the patient s weight loss curve. Weight loss results with LAGB are similar to other restrictive procedures; however, it may be less than RYGB, particularly in super obese patients (BMI 50 kg/m 2 ). 31,32,36-40 Nevertheless, LAGB is effective for weight Upper Gastrointestinal Examination Technique and Expected Findings After LAGB Early postoperative UGI after LAGB is useful to assess for band position, extraluminal leak, or obstruction. On a scout radiograph, the location and angle of the band, continuity of connecting tubing, and position of the reservoir are evaluated (Fig. 12B). Before administering contrast material, the patient should be positioned at fluoroscopy so the band is visualized in profile, most often supine anteroposterior or slight right posterior oblique (Fig. 12C). This position allows for optimal evaluation of the pouch and stoma and ensures that the opacified fundus does not obscure the stoma (Fig. 12). 34,42,43 Water-soluble contrast material is initially administered. If no leak is demonstrated, barium is administered. As with RYGB, attention is initially directed toward the postoperative anatomy: the pouch and stoma. Ingested contrast material flows from the esophagus into the pouch, through the stoma cre- Figure 11 RYGB: Small bowel obstruction with a dilated excluded limb. (A, B) Two contrast-enhanced axial CT images show a dilated excluded limb with pronounced gaseous distention of the excluded stomach (ES) and dilated, fluid-filled duodenum (D) and proximal jejunum (J). The Roux limb (arrow) is decompressed. A nasogastric tube cannot directly decompress the ES.

9 Imaging after bariatric surgery for morbid obesity 291 Figure 12 Laparoscopic adjustable gastric banding (LAGB): Expected anatomy and UGI technique. (A) Diagram depicting LAGB with an adjustable band placed around the proximal stomach to create a small gastric pouch (P). Tubing connects the band to a subcutaneous port. (B) A supine radiograph shows the gastric band (white arrow), connecting tubing (black arrows) and port (arrowhead). (C) A fluoroscopic spot image shows appropriate positioning for UGI. Before administration of contrast, the patient is positioned at fluoroscopy with the band imaged in profile (arrows) rather than as a ring shape. (D) Administered contrast material opacifies the gastric pouch (P), stoma (arrow), and fundus (F). (E) With improper patient positioning, contrast in the fundus (F) obscures the band (arrows) and stoma.

10 292 L.R. Carucci and M.A. Turner Figure 13 LAGB: Fluoroscopic band adjustment. (A) Supine UGI image before adjustment shows the stoma through the band (arrow), measuring approximately 8 mm (B) Fluoroscopic image shows localization of the port and advancement of a noncoring needle. (C) Supine UGI image after the addition of saline to inflate the cuff shows narrowing of the stoma, now measuring 2-3 mm (arrow). ated by the band and into the remainder of the stomach (Fig. 12). Esophageal motility and dilatation can be assessed along with pouch configuration and stomal diameter. There may be delayed esophageal emptying, with mild esophageal dilatation early after the surgery. 34 Late postoperative UGI may be performed for vomiting, food intolerance, insufficient weight loss, excessive weight loss, epigastric pain, or for planned adjustment. Similar technique is used; however, only barium is administered. Fluoroscopic evaluation allows for assessment of esophageal motility, pouch distention, obstruction, and changes over time. CT may be helpful to evaluate for a source of infection and to assess soft-tissue changes related to the tubing and reservoir. Band Adjustment Band adjustments are ideally carried out under fluoroscopy with UGI evaluation before and after adjustment (Fig. 13). The use of fluoroscopy allows for accurate adjustment of stomal size as well as reduction of complications from an excessively narrowed stoma, including obstruction, motility disorders, pouch enlargement, band slippage, and band migration. 44 Optimal stomal diameter is 3-5 mm and several band adjustments may be necessary to achieve this result; an average of 3 adjustments per patient is required for adequate weight reduction. 32,35,38,39,42,44 The extent of the adjustment is best determined in conjunction with the surgeon on the basis of the patient s symptomatology and weight loss curve. At fluoroscopy, the subcutaneous port is localized and accessed with a gauge noncoring, deflected-tip needle (Fig. 13). The wrong needle type or an inadvertent puncture of the tubing may cause damage and leakage from the system. 34,42 The noncoring needle with an attached, saline-filled syringe is advanced until it hits the back wall of the reservoir. Saline can be easily withdrawn or injected to confirm appropriate position. A designated volume of saline can then be injected or withdrawn to decrease or increase the stomal size, respectively. After adjustment, contrast material is adminis-

11 Imaging after bariatric surgery for morbid obesity 293 tered orally to confirm adequate narrowing of the stoma without obstruction (Fig. 13). 34,42 Complications After LAGB LAGB is a relatively safe procedure with minimal perioperative mortality; 31,34,36,38 however, some degree of morbidity occurs in up to 35% of patients. 13 Additional surgery may be necessary in 11% of patients; but most procedures can be performed laparoscopically and may be relatively minor. 13,31,36,37,39,45 Early complications of LAGB are rare and include gastroesophageal perforation ( 0.5%), improper band positioning ( 1%), early postoperative band slippage requiring repositioning ( 1%), and acute stomal obstruction ( 1.4%). 13,31,35-37,39,45 Early dysphagia occurs in up to 14% of patients and pouch esophageal reflux is common until dietary habits change. 35,38 Late LAGB complications are more common. The most common late complications of pouch dilatation and band slippage are best diagnosed with UGI and early diagnosis is important. 13,35,38,39 Other late complications include intragastric band migration, obstruction, and device-related complications, including device failure. 12,31,35-39,43,46 Gastric necrosis is rare ( 0.3% of patients) and is most often due to band slippage with strangulation. 31,36,37 Pouch Dilatation Pouch dilatation may occur in up to 25% of patients; however, the incidence has decreased with surgical modifications over time. 47 Dilatation of the pouch can result in failed weight loss and may necessitate band removal. Pouch dilatation may be seen with a normal or widened stoma, a narrow stoma, or due to band slippage. Pouch dilatation with a normal or widened stoma is most often a consequence of dietary noncompliance with chronic overfilling of the pouch. 38 There is chronic dilatation of the pouch with a concentric appearance. The larger pouch allows for further overeating and further dilatation. This type of pouch dilatation requires nutritional counseling. 35,38,42 The pouch may also become dilated because of a narrow stoma (Fig. 14). Here, pouch dilatation also appears concentric; however, dilatation occurs acutely and patients present with vomiting, dysphagia, esophageal dysmotility, or obstruction. 32,35,38 Acute pouch dilatation is most often caused by band over inflation at adjustment. Alternatively, acute pouch dilatation may rarely be due to a focal weakness in the band, resulting in eccentric stomal narrowing. This is difficult to appreciate on UGI and can be diagnosed by filling the band with contrast material at fluoroscopy. 35 When pouch dilatation because of a tight stoma is identified, the band should be deflated immediately. Prompt deflation may allow for resolution of pouch dilatation. If band deflation is delayed, dilatation will persist in up to 50% of patients and may be irreversible. 32 Figure 14 LAGB: Concentric pouch dilatation because of a narrow stoma. UGI image in a slight right posterior oblique position shows a concentrically dilated pouch (P), with a narrow stoma (arrows) through the band. Contrast material enters the gastric fundus (F). Pouch Dilatation With Band Slippage With band slippage, the band becomes dislocated with herniation of a portion of the stomach above the band and eccentric dilatation of the gastric pouch (Fig. 15). 34,41 Band slippage may occur in up to 24% of patients; however, the incidence varies with surgical technique. 35,36,38,45-50 There is also a decreased incidence of band slippage with patient training and modification of eating behaviors. 47 Risk factors for band slippage include overeating with overdistention of the pouch, band overinflation, and excessive vomiting. Band slippage is most often a late complication of LAGB, with a mean diagnosis of 13.4 months postoperatively. 36,37,49,51 Patients may present with acute food intolerance, pain, vomiting, progressive gastroesophageal reflux, esophageal motility disorders, early satiety, and aspiration pneumonia. 37,50,51 Rarely, band slippage may produce sudden complete dysphagia, severe abdominal pain, and acute gastric obstruction. 34,51 Three types of band slippage have been described, including anterior, posterior, and concentric slippage with complete displacement of the band distally. 50 In all cases, similar consequences are possible. At UGI, there is an abnormal band position with a change in comparison with a previous postoperative study. The band may be displaced inferiorly in a more vertical or horizontal configuration with an abnormal angle. There is eccentric pouch dilatation (Fig. 15). Gas within a distended gastric pouch above or below the band may be noted on a scout film. 35,36,38 Progressive eccentric pouch dilatation with progressive herniation of the stomach above the band may occur if left untreated. Early detection of band slippage is essential and the band should be deflated immediately to prevent further complications. 34,44 Repositioning or replacing the band is often necessary. 34,35,45,50,51 Band slippage can lead to acute obstruction, gastric volvulus, ischemia, infarction, perforation, and hemorrhage. 35,41,42 The most serious complication of LAGB is necrosis of the gastric pouch, which may occur because of band slippage. 48,51

12 294 L.R. Carucci and M.A. Turner Figure 15 LAGB: Eccentric pouch dilatation because of band slippage. (A) A supine radiograph shows an inferiorly located band with a horizontal configuration (arrow). (B) RPO UGI image shows a markedly dilated gastric pouch (P) above the inferiorly displaced band with a tight stoma (arrow). The pouch is dilated eccentrically because of band slippage with fundic herniation above the band. There is a partial obstruction at the band. F, fundus. Intragastric Erosion and Migration of the Band Intragastric erosion or migration of the band occurs in approximately 2% of LAGB patients, with higher frequencies reported with longer follow-up, likely related to the in-dwelling foreign body (ie, the gastric band). 12,36,46,47,51,52 With this complication, the band gradually erodes into the gastric wall and may enter the gastric lumen and even migrate distally. 12,35 Band erosion may be related to the use of nonsteroidal anti-inflammatory medicine, excessive vomiting, or increased band pressure from overinflation. 35,36 Patients may present with nonspecific pain, gastrointestinal bleeding, abdominal and/or port abscess, peritonitis, perforation, and rarely pneumoperitoneum. 12,35,52 Band erosion may be associated with weight gain despite seemingly adequate band adjustment. At UGI, contrast material is seen within the stoma as well as surrounding the intragastric portion of the band such that the band appears as an intraluminal filling defect. 12,35 Band migration typically requires urgent band removal and repair of the stomach, as band erosion can lead to fatal hemorrhage. 12,35,52 Device-Related Complications Device-related complications involving the port, connecting tubing, or band have been reported in up to 26% of patients and typically require surgical repair. 13,39,53 The port may migrate through the soft-tissues or become inverted in up to 3% of patients, preventing band adjustment. 12,34,36,53 Infection involving the port or band occurs in 6% and 3% of patients, respectively. 31,35-38,53 Leakage of fluid from the system with spontaneous band deflation may occur in 5% of patients. 12,35,36,43,53 Fluid loss may occur from the port, tubing, or inflatable cuff of the band. Acute band deflation widens the stoma and patients experience a sudden change in dietary habits. 35,43,53,54 There is associated poor weight loss despite seemingly appropriate band adjustments. If leakage from the system is suspected, a plain film can be obtained to assess for acute angulation or discontinuity of the connecting tubing. Suspected leak from the system may be confirmed by inserting a designated volume of saline into the port and measuring for a discrepancy on return. However, the source of the leak is important to direct surgical intervention and injecting the port with water-soluble contrast material at fluoroscopic can distinguish leak from the port, tubing, or band. 42,54 Summary Obesity is a serious health problem in the United States and European countries. With failed conservative treatment and proven effectiveness of bariatric surgery, surgical procedures for morbid obesity are increasingly performed. RYGB and LAGB are the 2 most popular bariatric procedures performed currently in the United States. Bariatric surgery patients are often evaluated with UGI and/or CT, and findings of weight loss surgery may be incidental at the time of imaging for other indications. Understanding the procedures and appropriate examination techniques after bariatric surgery is essential to diagnose potential complications accurately. Radiologists must be familiar with the expected postoperative anatomy,

13 Imaging after bariatric surgery for morbid obesity 295 potential pitfalls of diagnosis, and complications that may occur after these procedures. References 1. Buchwald H: Consensus conference statement bariatric surgery for morbid obesity: health implications for patients, health professionals, and third-party payers. Surg Obes Relat Dis 1: , Chandler RC, Srinivas G, Chintapalli KN, et al: Imaging in bariatric surgery: a guide to postsurgical anatomy and common complications. AJR 190: , Gastrointestinal surgery for severe obesity: National Institutes of Health Consensus Development Conference Statement. Am J Clin Nutr 55: 615S-619S, Brolin RE: Update: NIH consensus conference. Gastrointestinal surgery for severe obesity. Nutrition 12: , Fisher BL, Schauer P: Medical and surgical options in the treatment of severe obesity. Am J Surg 184:9S-16S, Santry HP, Gillen DL, Lauderdale DS: Trends in bariatric surgical procedures. J Am Med Assoc 294: , DeMaria EJ, Sugerman HJ, Kellum JM, et al: Results of 281 consecutive total laparoscopic roux-en-y gastric bypasses to treat morbid obesity. Ann Surg 235: , 2002; discussion Higa KD, Boone KB, Ho T: Complications of the laparoscopic rouxen-y gastric bypass: 1040 patients what have we learned? Obes Surg 10: , Schauer PR, Ikramuddin S, Gourash W, et al: Outcomes after laparoscopic roux-en-y gastric bypass for morbid obesity. Ann Surg 232: , Sugerman HJ: Gastric bypass surgery for severe obesity. Semin Laparosc Surg 9:79-85, Sarker S, Myers J, Serot J, et al: Three-year follow-up weight loss results for patients undergoing laparoscopic adjustable gastric banding at a major University Medical Center: does the weight loss persist? Am J Surg 191: , Hainaux B, Agneessens E, Rubesova E, et al: Intragastric band erosion after laparoscopic adjustable gastric banding for morbid obesity: imaging characteristics of an underreported complication. AJR 184: , Suter M, Giusti V, Worreth M, et al: Laparoscopic gastric banding: a prospective, randomized study comparing the Lapband and the SAGB: early results. Ann Surg 241:55-62, Fobi MA, Lee H, Holness R, et al: Gastric bypass operation for obesity. World J Surg 22: , Goodman P, Halpert RD: Radiological evaluation of gastric stapling procedures for morbid obesity. Crit Rev Diagn Imaging 32:37-67, Carucci LR, Turner MA, Conklin RC, et al: Roux-en-Y gastric bypass surgery for morbid obesity: evaluation of postoperative extraluminal leaks with upper gastrointestinal series. Radiology 238: , Buckwalter JA, Herbst CA Jr: Leaks occurring after gastric bariatric operations. Surgery 103: , Carucci LR, Turner MA, Yu J: Imaging evaluation following roux-en-y gastric bypass surgery for morbid obesity. Radiol Clin North Am 45: , Carucci LR, Conklin RC, Turner MA: Roux-en-Y gastric bypass surgery for morbid obesity: evaluation of leak into excluded stomach with upper gastrointestinal examination. Radiology 248: , Buckwalter JA, Herbst CA Jr: Complications of gastric bypass for morbid obesity. Am J Surg 139:55-60, 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 179: , Blachar A, Federle MP, Pealer KM, et al: Gastrointestinal complications of laparoscopic roux-en-y gastric bypass surgery: clinical and imaging findings. Radiology 223: , Champion JK, Williams M: Small bowel obstruction and internal hernias after laparoscopic roux-en-y gastric bypass. Obes Surg 13: , Filip JE, Mattar SG, Bowers SP, et al: Internal hernia formation after laparoscopic roux-en-y gastric bypass for morbid obesity. Am Surg 68: , Higa KD, Ho T, Boone KB: Internal hernias after laparoscopic rouxen-y gastric bypass: incidence, treatment and prevention. Obes Surg 13: , Iannelli A, Buratti MS, Novellas S, et al: Internal hernia as a complication of laparoscopic roux-en-y gastric bypass. Obes Surg 17: , Carucci LR, Turner MA, Shaylor SD: Internal hernia following rouxen-y gastric bypass surgery for morbid obesity: evaluation of radiographic findings at small-bowel examination. Radiology 251:762-70, Blachar A, Federle MP, Dodson SF: Internal hernia: clinical and imaging findings in 17 patients with emphasis on CT criteria. Radiology 218:68-74, Lockhart ME, Tessler FN, Canon CL, et al: Internal hernia after gastric bypass: sensitivity and specificity of seven CT signs with surgical correlation and controls. AJR 188: , Reddy SA, Yang C, McGinnis LA, et al: Diagnosis of transmesocolic internal hernia as a complication of retrocolic gastric bypass: CT imaging criteria. AJR 189:52-55, DeMaria EJ, Jamal MK: Laparoscopic adjustable gastric banding: evolving clinical experience. Surg Clin North Am 85: , vii, Hainaux B, Coppens E, Sattari A, et al: Laparoscopic adjustable silicone gastric banding: radiological appearances of a new surgical treatment for morbid obesity. Abdom Imaging 24: , Kuzmak LI: A review of seven years experience with silicone gastric banding. Obes Surg 1: , Szucs RA, Turner MA, Kellum JM, et al: Adjustable laparoscopic gastric band for the treatment of morbid obesity: radiologic evaluation. AJR 170: , Wiesner W, Schob O, Hauser RS, et al: Adjustable laparoscopic gastric banding in patients with morbid obesity: radiographic management, results, and postoperative complications. Radiology 216: , Chevallier JM, Zinzindohoue F, Douard R, et al: Complications after laparoscopic adjustable gastric banding for morbid obesity: experience with 1000 patients over 7 years. Obes Surg 14: , Zinzindohoue F, Chevallier JM, Douard R, et al: Laparoscopic gastric banding: a minimally invasive surgical treatment for morbid obesity: prospective study of 500 consecutive patients. Ann Surg 237:1-9, Zacharoulis D, Roy-Chadhury SH, Dobbins B, et al: Laparoscopic adjustable gastric banding: surgical and radiological approach. Obes Surg 12: , Favretti F, Cadiere GB, Segato G, et al: Laparoscopic banding: selection and technique in 830 patients. Obes Surg 12: , Mognol P, Chosidow D, Marmuse JP: Laparoscopic gastric bypass versus laparoscopic adjustable gastric banding in the super-obese: a comparative study of 290 patients. Obes Surg 15:76-81, Mehanna MJ, Birjawi G, Moukaddam HA, et al: Complications of adjustable gastric banding, a radiological pictorial review. AJR 186: , Carucci LR, Turner MA, Szucs RA: Adjustable laparoscopic gastric banding for morbid obesity: imaging assessment and complications. Radiol Clin North Am 45: , Pomerri F, De Marchi F, Barbiero G, et al: Radiology for laparoscopic adjustable gastric banding: a simplified follow-up examination method. Obes Surg 13: , Frigg A, Peterli R, Zynamon A, et al: Radiologic and endoscopic evaluation for laparoscopic adjustable gastric banding: preoperative and follow-up. Obes Surg 11: , Weiner R, Blanco-Engert R, Weiner S, et al: Outcome after laparoscopic adjustable gastric banding - 8 years experience. Obes Surg 13: , 2003

14 296 L.R. Carucci and M.A. Turner 46. Ponce J, Paynter S, Fromm R: Laparoscopic adjustable gastric banding: 1014 consecutive cases. J Am Coll Surg 201: , Zappa MA, Micheletto G, Lattuada E, et al: Prevention of pouch dilatation after laparoscopic adjustable gastric banding. Obes Surg 16: , Iannelli A, Facchiano E, Sejor E, et al: Gastric necrosis: a rare complication of gastric banding. Obes Surg 15: , Weiner R, Bockhorn H, Rosenthal R, et al: A prospective randomized trial of different laparoscopic gastric banding techniques for morbid obesity. Surg Endosc 15:63-68, Wolnerhanssen B, Kern B, Peters T, et al: Reduction in slippage with 11-cm lap-band and change of gastric banding technique. Obes Surg 15: , Kriwanek S, Schermann M, Ali AS, et al: Band slippage a potentially life-threatening complication after laparoscopic adjustable gastric banding. Obes Surg 15: , Abu-Abeid S, Bar Zohar D, Sagie B, et al: Treatment of intragastric band migration following laparoscopic banding: safety and feasibility of simultaneous laparoscopic band removal and replacement. Obes Surg 15: , Keidar A, Carmon E, Szold A, et al: Port complications following laparoscopic adjustable gastric banding for morbid obesity. Obes Surg 15: , Mittermair RP, Weiss HG, Nehoda H, et al: Band leakage after laparoscopic adjustable gastric banding. Obes Surg 13: , 2003