Imaging studies after bariatric surgery

INTRODUCTION — Postoperative radiographic imaging studies following bariatric surgical procedures are typically obtained to identify the integrity and patency of anastomoses and to identify postoperative complications (eg, anastomotic leaks) precisely and early. In addition, for patients who have had a gastric banding procedure, radiographic images allow for evaluation of band position and the size of the gastric pouch.

This topic review will present the normal and abnormal findings seen on radiologic evaluation after gastric banding, gastric bypass, sleeve gastrectomy, and biliopancreatic diversion. An overview of the various bariatric procedures and their complications and the role of endoscopic management of gastrointestinal complications of the most common bariatric surgical procedures are presented separately. (See "Bariatric surgery for management of obesity: Indications and preoperative preparation" and "Bariatric operations: Late complications with subacute presentations" and "Gastrointestinal endoscopy in patients who have undergone bariatric surgery".)

THE ROLE OF IMAGING AFTER BARIATRIC SURGERY — There is no consensus as to whether imaging should be performed routinely or selectively following bariatric surgery [1-3]. Before initiating a diet, most bariatric surgeons who obtain imaging following bariatric procedures that involve an anastomosis or stapling get an upper gastrointestinal (UGI) series on postoperative day 1. The advantage of this approach is that any leak, if present, can be addressed quickly. However, some surgeons only perform postoperative imaging selectively, based upon the patient's clinical progress [3-5].

A systematic review evaluated the sensitivity and specificity of UGI from data obtained from 19 studies involving 10,139 patients [6]. UGI had an overall sensitivity of 54 percent and a specificity of 100 percent for detecting anastomotic leak within two days of bariatric surgery. The threshold used to distinguish between positive and negative test results varied between institutions. Given the moderate sensitivity, the authors of this study suggested that treating marginal radiological evidence of leakage as presumptively positive maximizes the clinical utility of UGI. Although a majority of articles show that UGI series are better for identifying leak following bariatric surgery, a later study found better sensitivity and specificity with abdominal computed tomography (CT) compared with UGI (100 versus 95 percent) [7]. Regardless of the imaging modality chosen, any clinical suspicion of leak warrants investigation.

When bariatric surgery patients present with complaints of heartburn, nausea or vomiting, abdominal pain, or weight loss failure, imaging studies should be obtained to ensure prompt diagnosis of infection, obstruction, ischemia, or mechanical or technical failures of an operation [8,9]. Radiologic examination of bariatric patients can be technically difficult because of patient size, resulting in suboptimal imaging [10].

Radiologic evaluation and endoscopy are complementary studies, and endoscopy is often necessary for diagnostic certainty in bariatric patients with postoperative complications [11]. Usually, imaging is performed first, and then a decision about proceeding to endoscopy is made based upon the imaging findings and the patient's symptoms. (See "Gastrointestinal endoscopy in patients who have undergone bariatric surgery".)

GASTRIC BANDING — Laparoscopic adjustable gastric banding (LAGB) is a purely restrictive procedure that compartmentalizes the upper stomach by placing a soft, adjustable silicone ring around the entrance to the stomach (figure 1). The gastric band is connected to an infusion port placed in the subcutaneous tissue. The band diameter and degree of gastric restriction can be adjusted via the port by withdrawing or injecting saline from the port. (See "Bariatric procedures for the management of severe obesity: Descriptions", section on 'Laparoscopic adjustable gastric banding'.)

Normal postoperative findings after LAGB — The band should be visible just below the gastroesophageal junction at a 45 degree angle toward the left shoulder with the medial aspect of the band juxtaposed to the left pedicle of the vertebra [12]. Normally, the band points to the 2 o'clock and 8 o'clock position on x-ray (image 1).

Abnormalities on imaging after LAGB — Most of the complications of LAGB are due to a band that is too tight, slips into the wrong position, or erodes through the stomach wall. A tight band can lead to symptoms of heartburn, nausea, vomiting, or abdominal pain. Another cause of abdominal pain and complications after LAGB is disconnected port tubing, which can migrate and lead to obstruction or compression of other organs. Rarely, acute abdominal pain is caused by erosion and perforation following placement of a gastric band. (See "Bariatric operations: Late complications with subacute presentations", section on 'Adjustable gastric banding'.)

For patients who have complications after gastric banding, an abdominal x-ray with posteroanterior and oblique views and an esophagram with a water-soluble contrast (eg, Gastrografin) will provide the most useful diagnostic information [8]. These tests can detect band slippage, gastric prolapse, pouch dilation, esophageal dilation or spasm, or a hiatal hernia. A CT scan may also be needed if the patient's symptoms do not seem to be related to the gastric band or if a diagnosis is not made with plain films or esophagram.

Endoscopy is also useful for detection of band erosion. Endoscopic findings after bariatric surgery are discussed elsewhere. (See "Gastrointestinal endoscopy in patients who have undergone bariatric surgery", section on 'Adjustable gastric band'.)

The imaging findings for complications after LAGB are discussed below.

Band slippage and gastric prolapse — Gastric prolapse is caused by band slippage and migration of the stomach above the band, which causes varying degrees of gastric obstruction associated with pain in the left upper quadrant, left chest, or back. Gastric prolapse can be identified on an abdominal x-ray by the axis of the band if it has shifted from the usual "2 to 8 o'clock" to a more horizontal "10 to 4 o'clock" position (image 2). An esophagram will demonstrate the outline of the pouch with rugal folds above the band (figure 2 and image 3).

If a prolapse is identified and pain persists after the band is loosened, urgent surgical exploration to reposition, replace, or remove the band is indicated. (See "Bariatric operations: Late complications with subacute presentations", section on 'Band slippage and gastric prolapse'.)

Pouch dilation — In contrast to gastric prolapse, which is associated with gastric obstruction, pouch dilation is enlargement of the gastric pouch without obstruction and without any change in the angle of the band [12,13]. Pouch enlargement is caused by overinflation of the band or overeating. The diagnosis is made on upper gastrointestinal (UGI) series (image 4).

Pouch dilation will usually respond to nonoperative treatment with band deflation, a low-calorie diet, and small portion sizes for four to six weeks. The band can then be reinflated incrementally. If this is unsuccessful and the pouch does not return to its original size, surgical removal or replacement is indicated [12].

Esophageal dilation — Esophageal dilation proximal to the band device or "pseudoachalasia syndrome" may develop when the band is too tight or with excessive amounts of food intake (image 5). Typically, patients with esophageal dilation present with food and saliva intolerance, reflux, and epigastric discomfort. Patients can also experience substernal chest pain. An esophagram usually identifies both esophageal and pouch dilation (image 4).

The treatment for a tight band is to deflate the band and allow the esophagus or stomach to regain its tone. If loosening the band does not resolve the symptoms, band removal is required. (See "Gastrointestinal endoscopy in patients who have undergone bariatric surgery", section on 'Esophageal dilation' and "Bariatric operations: Late complications with subacute presentations", section on 'Esophageal dilatation or esophagitis'.)

Esophageal spasm — Esophageal spasm typically presents as severe or squeezing chest pain. Esophageal spasm can accompany esophagitis from reflux, when the band is too loose, or can reflect an underlying esophageal motility disorder [14]. Radiographic findings are variable in patients suspected of having esophageal spasms and may demonstrate severe nonperistaltic contractions, which may produce striking abnormalities in the barium column, termed "rosary bead" or "corkscrew" esophagus (image 6 and image 7). However, esophageal spasm is difficult to capture on imaging, and the diagnosis should be based upon associated clinical and manometric findings. The treatment of esophageal spasm is discussed elsewhere. (See "Distal esophageal spasm and hypercontractile esophagus".)

Hiatus hernia — Hiatal hernia refers to herniation of elements of the abdominal cavity through the esophageal hiatus of the diaphragm. This is often a preexisting but unrecognized condition in patients undergoing bariatric surgery and can lead to ongoing intractable reflux necessitating reoperation or band removal (image 8) [15]. The diagnosis of hiatal hernia is made with a combination of radiography, endoscopy, and esophageal manometry. This is discussed elsewhere. (See "Hiatus hernia", section on 'Classification' and "Bariatric operations: Late complications with subacute presentations", section on 'Adjustable gastric banding'.)  

Band erosion — Band erosion through the wall of the stomach can be caused by an excessively tight band or injury to the gastric wall during placement (figure 3 and picture 1 and image 9). Erosions typically present months after the initial surgery; however, erosions in the immediate postoperative period have been described [16,17]. Band erosion can cause epigastric pain, gastrointestinal bleeding, intra-abdominal abscesses, and/or port site infection [12]. An esophagram and/or an endoscopy will show evidence of gastric band erosion, which is not always visible on CT scan.

Band erosion is managed with removal of the band and closure of the gastrotomy. (See "Bariatric operations: Late complications with subacute presentations", section on 'Band erosion' and "Gastrointestinal endoscopy in patients who have undergone bariatric surgery", section on 'Band erosion'.)

Tubing migration or disconnection — The tubing can disconnect from the port and cause abdominal pain by migrating and causing pressure. In such cases, a radiograph will show the tubing separated from the port. The abdominal quadrant where the end of the tubing lies often corresponds with the patient's pain. The tubing can also migrate and cause obstructive symptoms by wrapping around intra-abdominal organs or around the base of the mesentery (image 10 and image 11 and image 12) [18].

Disconnected or migrated tubing requires surgical repair. (See "Bariatric operations: Late complications with subacute presentations", section on 'Port malfunction or infection'.)

Perforation — After gastric banding or a revision of gastric banding, severe abdominal pain should raise concern for a possible perforation, although this is extremely rare [19]. In such cases, an acute abdominal series demonstrates free air and a UGI series demonstrates leakage of contrast (image 13). A CT should be obtained if the plain films do not confirm the clinically suspected diagnosis.

Esophageal reflux — Esophageal reflux can lead to esophagitis, esophageal erosions, and strictures, which, in turn, cause maladaptive eating patterns and failure of weight loss. In such cases, patients tend to eat softer foods that are easier to swallow but are more calorically dense. A limited UGI, which visualizes the esophagus and stomach but does not follow contrast into the small bowel, will show reflux of the contrast material into the esophagus and may show thickening of the esophageal folds, ulcerations, or strictures. However, radiography is not diagnostic, because reflux can be provoked in normal patients as well. If esophageal reflux is suspected, endoscopy is generally indicated to confirm the diagnosis. (See "Clinical manifestations and diagnosis of gastroesophageal reflux in adults", section on 'Radiographic findings'.)

ROUX-EN-Y GASTRIC BYPASS — The Roux-en-Y gastric bypass (RYGB) is characterized by a small (less than 30 mL) proximal gastric pouch divided and separated from the stomach remnant, with drainage of food to the rest of the gastrointestinal tract via a gastrojejunal anastomosis and a Roux-en-Y small bowel anastomosis (figure 4). An RYGB procedure results in three "limbs": the Roux limb, which is anastomosed to the stomach; the biliopancreatic (BP) limb, which is anastomosed to the Roux limb; and the common channel (CC), which continues to the terminal ileum and cecum [8]. (See "Bariatric procedures for the management of severe obesity: Descriptions", section on 'Roux-en-Y gastric bypass'.)

Normal postoperative findings after RYGB — A limited upper gastrointestinal series (UGI) series will demonstrate the pouch size, the gastrojejunal anastomosis, and the Roux limb diameter (image 14). The gastric pouch volume should be approximately 30 mL, which is similar to the size of a lower thoracic or lumbar vertebral body [9,10]. This comparison allows fast and reliable identification of a pouch that is too large or too small. The gastric pouch can extend toward the spleen on a UGI series and may be misdiagnosed as a leak. It is important to ensure that this region of the pouch empties on subsequent views to make this determination.

Contrast medium in the jejunal limb should demonstrate normal mucosal folds and motility. The duodenum, the excluded stomach, and the distal anastomosis are difficult to visualize on the UGI series. It is not unusual for the Roux limb to be slightly dilated up to 3 cm post-gastric bypass, presumably due to the division of the small bowel to create the Roux-en-Y. Narrowing of the gastrojejunostomy with delayed pouch emptying is usually a sign of normal postoperative edema [9].

CT scan imaging after gastric bypass will identify the gastric pouch, the position of the Roux limb (antecolic antegastric, retrocolic antegastric, or retrocolic retrogastric), the size of the remnant stomach, and the position and size of the three limbs (Roux, BP, and CC) (image 15). The excluded stomach may contain a small amount of air but should not be distended. The limbs, native duodenum, and proximal jejunum should not be greater than 2.5 cm in diameter [10].

Most bariatric surgeons place the Roux limb medial to the BP limb. However, the position of the Roux limb and BP limb can be reversed depending upon the approach used by the surgeon to perform the gastric bypass. The operative note should be reviewed, if possible, to help interpret the imaging findings.

Abnormalities on imaging after RYGB — Complications after RYGB include stenosis, marginal ulcer, gastrogastric fistula, obstruction, internal hernia, hiatal hernia, leak, Roux stasis syndrome, and pouch enlargement. For patients who present with problems after Roux-en-Y gastric bypass, the evaluation is guided by the patient's symptoms and timing of symptom presentation (eg, early postoperative period [within 30 days after surgery] or later) [8].

●Early complications, such as leaks, are usually identified on a UGI series. If a leak is suspected and the UGI is negative, a CT scan can be obtained. However, re-exploration may be necessary without definitive imaging if a leak is suspected clinically and the patient is not stable enough for the CT scanner. If an abscess or fluid collection is suspected, CT of the abdomen and pelvis will provide the most useful information.

●For later complications, such as obstruction, an abdominal x-ray and a CT of the abdomen and pelvis provide the most useful information. Upper endoscopy may also be necessary if indicated by imaging findings or if the imaging studies fail to provide a diagnosis. (See "Bariatric operations: Late complications with subacute presentations", section on 'Roux-en-Y gastric bypass' and "Gastrointestinal endoscopy in patients who have undergone bariatric surgery", section on 'Roux-en-Y gastric bypass'.)

The imaging findings for complications after RYGB are discussed below.

Gastrojejunal stenosis — Gastrojejunal stenosis after RYGB will lead to postprandial epigastric pain and vomiting and can be diagnosed on a limited UGI series [10]. The stoma should be approximately 12 mm in diameter. Stenosis can also be identified by upper endoscopy (picture 2).

The treatment of stenosis with balloon dilation is discussed elsewhere. (See "Gastrointestinal endoscopy in patients who have undergone bariatric surgery", section on 'Stomal (anastomotic) stenosis'.)

Marginal ulcer — A marginal ulcer can form on the jejunal side of the gastrojejunostomy after gastric bypass, causing pain, nausea, bleeding, and/or perforation. Marginal ulcers are difficult to detect on UGI or CT scans, and the diagnosis is usually made on endoscopy (picture 3). Medical management is usually successful. Surgical revision is rarely needed but may be necessary for persistent pain or recurrent bleeding, despite maximal medical management.

If a marginal ulcer does not heal with medical management, a limited UGI should be obtained to detect a gastrogastric fistula, which can cause reflux and increased acid exposure for the gastrojejunostomy (image 16). (See "Indications and diagnostic tests for Helicobacter pylori infection in adults" and "Bariatric operations: Late complications with acute presentations", section on 'Marginal ulcers'.)

Gastrogastric fistula — A gastrogastric fistula is a communication between the gastric pouch and the gastric remnant. This can lead to reflux, abdominal pain, and weight regain. A gastrogastric fistula can be identified on limited UGI series or CT scan. If suspected and not seen on UGI, an upper endoscopy can be performed to evaluate the gastric pouch and anastomosis (image 16).

If gastrogastric fistula is present in a patient with poor weight loss or gradual weight regain, repair or closure by surgery or endoscopy is indicated.

Obstruction — Obstruction will cause nausea, vomiting, and pain. Occasionally, an obstruction of the biliopancreatic limb alone will result in bloating and hiccups rather than nausea and vomiting [10]. An obstruction can be due to adhesions; an intraluminal cause, such as a blood clot; or an internal hernia (discussed below) (image 17 and image 18 and image 19). The level of the obstruction can be determined by whether the emesis is bilious or nonbilious. Bilious emesis implies an obstruction at the enteroenterostomy or in the common channel, while nonbilious emesis implies an obstruction in the Roux limb or at the enteroenterostomy.

A CT scan of the abdomen is the most useful imaging study in patients with obstruction of the common channel and will show dilation proximal to the obstruction and dilation of the BP limb, gastric remnant, and Roux limb. Obstruction of the Roux limb will show collapse of the CC and BP limbs with dilation of the Roux limb (image 20) [8].

Internal hernia — An internal hernia is caused by a mesenteric defect (Petersen's defect), which is created when performing the Roux-en-Y procedure (image 18). Closure of the mesenteric and Petersen's defects at the time of bypass reduces the incidence of bowel obstruction in the postoperative period [20,21]. However, the defects can recur with significant weight loss [20,22,23].

A UGI series with small bowel follow-through or a CT scan can show clustering of the small bowel in the left upper quadrant, which is a sign of an internal hernia [24]. A CT scan of the abdomen will show evidence of an internal hernia, with a swirled appearance of the mesenteric vessels in the superior mesenteric artery region ("mesenteric swirl sign") (image 21 and image 22) [25,26]. For pregnant patients who need to avoid radiation, magnetic resonance imaging can be obtained if an internal hernia is suspected (image 23) [27].

If a patient is suspected to have an internal hernia as the etiology of abdominal pain, urgent surgical exploration is indicated. (See "Bariatric operations: Late complications with acute presentations", section on 'Small bowel obstruction'.)

Hiatal hernia after RYGB — Hiatal hernia is often a preexisting but unrecognized condition in patients undergoing bariatric surgery and can cause intractable reflux, nausea, and abdominal pain (image 24). (See "Hiatus hernia", section on 'Management'.)

Leak — Abdominal pain and fever after a gastric bypass are a concern for a leak at either the gastrojejunostomy or the enteroenterostomy. A leak can generally be identified on a UGI series and/or CT of the abdomen and pelvis. Either imaging modality will show extraluminal contrast material (image 25 and image 26). The clinical assessment of the patient is critical if there is any question about the radiographic image. If a leak is suspected clinically, urgent surgical exploration should be performed even if the imaging is negative, given the potential for rapid progression to sepsis in such patients. (See "Bariatric operations: Early (fewer than 30 days) morbidity and mortality", section on 'Gastrointestinal leak'.)

Abscess — CT scan plays a critical role in the evaluation of patients suspected of having an abscess or abdominal fluid collection [10]. It is prudent to obtain the CT scan on the interventional scanner so that percutaneously CT-guided aspiration or drainage of an abscess or fluid collection can be performed immediately if detected.

Roux stasis syndrome — The Roux stasis syndrome is due to a motility disorder of the Roux limb as a consequence of surgical separation from the natural small intestinal pacemaker in the duodenum. Roux stasis syndrome causes abdominal pain, vomiting, and early satiety. In most cases, this syndrome can be diagnosed by limited UGI series (image 27) [28].

Most patients with Roux stasis syndrome can be managed in the same manner as those with chronic intestinal pseudo-obstruction. Some patients who have retained food predominantly in the gastric remnant require subtotal gastrectomy. (See "Chronic intestinal pseudo-obstruction: Etiology, clinical manifestations, and diagnosis".)

Pouch enlargement — Technical failure of a gastric bypass is characterized by either gastric pouch enlargement or dilation of the gastrojejunostomy. Patients with pouch enlargement are able to eat "normal" portions and experience weight regain from their lack of restriction [29]. A limited UGI series will usually demonstrate the size of the gastric pouch and possibly the stomal diameter of the gastrojejunostomy. Endoscopy will also show a dilated gastrojejunostomy and can measure pouch size (picture 4).

SLEEVE GASTRECTOMY — Sleeve gastrectomy (SG) is a partial gastrectomy in which the majority of the greater curvature of the stomach is removed and a tubular stomach is created (figure 5).

Normal postoperative findings after SG — The normal postoperative appearance of an SG is an upside-down seven (image 28). Occasionally, spasm at the angularis will give the appearance of a stricture or of a dilated proximal sleeve.

Abnormalities on imaging after SG — Complications after SG include hiatal hernia, angulation or stricture of the sleeve, dilated sleeve, dumbbell sleeve, leak, and mesenteric venous thrombosis. For patients who have complications following SG, a limited upper gastrointestinal (UGI) series and endoscopy will usually identify the common underlying problems, such as dilation or stricture of the sleeve. A limited UGI series will demonstrate the reduction in gastric volume, the rate of emptying of the sleeve, evidence of spasm, or the presence of a leak. The imaging findings for these diagnoses are discussed below. Endoscopy findings are discussed elsewhere. (See "Gastrointestinal endoscopy in patients who have undergone bariatric surgery", section on 'Sleeve gastrectomy' and "Bariatric operations: Late complications with subacute presentations", section on 'Sleeve gastrectomy'.)

Hiatal hernia after SG — Hiatal hernia refers to herniation of elements of the abdominal cavity through the esophageal hiatus of the diaphragm. Hiatal hernias are exacerbated by obesity and can cause intractable reflux, nausea, and abdominal pain (image 29) [30,31]. The diagnosis of hiatal hernia is made with a combination of radiographic imaging, endoscopy, and esophageal manometry. A UGI will show the gastroesophageal (GE) junction above the diaphragm. The diagnosis and treatment of hiatal hernia is discussed elsewhere. (See "Hiatus hernia", section on 'Management'.)

Stricture or stenosis of the SG — A stricture, angulation, or corkscrew configuration of the sleeve can result in nausea, heartburn, vomiting, and chest pain or abdominal pain due to changes in the lower esophageal sphincter pressure (image 30 and picture 5) [32-35]. This may occur soon after surgery or can appear weeks to months after the operation.

The most common reasons for the development of narrowing or stenosis are over-sewing the staple line and using a bougie that is too small. A stricture may also occur adjacent to a leak. The gastroesophageal junction and the incisura angularis are the two most common areas where stenosis occurs, and this can be diagnosed by a UGI series, which will show kinking, tortuosity, or a long thinning or lack of progression of contrast.

Management of stenosis primarily consists of endoscopic dilation. If the area of stenosis is too long, surgical intervention may be necessary with conversion to a gastric bypass, gastric stricturoplasty, or resection with gastrogastrostomy. (See "Bariatric operations: Late complications with subacute presentations", section on 'Sleeve gastrectomy'.)

Dilated SG — A dilated sleeve may lead to failure of weight loss or weight regain. This can best be assessed on limited UGI series (image 31) [36]. A dilated sleeve can be corrected with a repeat gastric sleeve to reduce the gastric sleeve volume [37].

Dumbbell SG — A "dumbbell sleeve" is a wide, dilated fundus with a relatively narrow midstomach but without complete obstruction. This can cause nausea and vomiting after sleeve gastrectomy and can be identified on limited UGI series (image 32) [38].

This may require conversion to a gastric bypass, or the fundus may need to be "re-sleeved." It is crucial to ensure that there is not a stricture at the angularis prior to proceeding with a "re-sleeve" of the fundus.

Leak after SG — Abdominal pain after SG may represent a leak (image 33). Most leaks are due to local factors at the site of the staple line, such as inadequate blood supply and oxygenation, which impede the healing process. Leaks can also be due to gastric wall ischemia, a consequence of the heat generated by the electrocautery used during dissection of the greater curve. Although the blood supply to the stomach is robust, the gastroesophageal junction tends to be an area of decreased vascularity and thus more prone to perforation and leaks. SG produces high intragastric pressure, which can also be a causative factor in a leak. High gastric pressures can affect the healing process and lengthen the amount of time for a leak to close.

The best modality to identify a leak is an esophagram/limited UGI series, although a CT scan of the upper abdomen with contrast may also demonstrate the leak. Abscess formation in the postoperative period is best diagnosed by a CT scan of the abdomen (image 34).

If a leak is diagnosed within a week after SG, reoperation with primary repair is the best option. If the leak is diagnosed later, drainage and stenting of the leak are options. (See "Bariatric operations: Late complications with subacute presentations", section on 'Sleeve gastrectomy'.)

Mesenteric venous thrombosis — Mesenteric venous thrombosis has been identified with increasing frequency in the sleeve gastrectomy patient, although it can also occur following other bariatric surgical procedures such as the gastric bypass procedure [39]. Mesenteric venous thrombosis is likely due to dehydration, which is more common after sleeve gastrectomy than with other bariatric procedures. Patients who have sleeve gastrectomies often have difficulty with nausea and have delayed gastric emptying, all of which contribute to less fluid intake and dehydration. The diagnosis of mesenteric venous thrombosis is made by a CT scan of the abdomen (image 35) [39].

Standard initial treatment for acute mesenteric venous thrombosis includes heparin anticoagulation and resection of infarcted bowel. (See "Mesenteric venous thrombosis in adults", section on 'Anticoagulation'.)

BILIOPANCREATIC DIVERSION (BPD) WITH OR WITHOUT DUODENAL SWITCH (DS) — A BPD/DS consists of a partial gastrectomy, which is essentially a sleeve gastrectomy (SG), along with a bypass procedure (gastroileostomy or duodenoileostomy) (figure 6). (See "Bariatric procedures for the management of severe obesity: Descriptions", section on 'Biliopancreatic diversion with duodenal switch'.)

Normal postoperative findings after BPD/DS — A CT scan or upper gastrointestinal (UGI) series in a BPD/DS patient will demonstrate the SG, the gastroileostomy or duodenoileostomy, and the relationship of the alimentary limb to the biliopancreatic limb (image 36). The alimentary limb will contain the contrast, and the BP limb will be non-opacified until the distal anastomosis and the common channel.

Abnormalities on imaging after BPD/DS — Complications after BPD/DS are due to either the SG or the gastroileostomy or duodenoileostomy portion of the procedure. For patients with complications following BPD, the evaluation is guided by the patient's symptoms and whether these arise in the early postoperative period (within 30 days after surgery) or later. Early complications such as leaks can generally be identified on a UGI series and CT of the abdomen and pelvis. For later complications, a CT of the abdomen and pelvis and an upper endoscopy are more likely to demonstrate the abnormality.

Sleeve-related complications — The complications of the SG portion of the BPD are similar to those described following an SG alone, and the radiographic imaging findings are also similar (image 31) [40]. However, because the SG in a DS is performed over a larger bougie, more contrast may be necessary to adequately distend the "sleeved" stomach for imaging. (See 'Sleeve gastrectomy' above.)

Bypass-related complications — The complications of the bypass portion of the BPD are similar to those described following gastric bypass, with similar radiographic imaging findings. Common complications of the BPD include strictures of the duodenoileostomy or the gastroileostomy, leaks, marginal ulcers, hiatal hernia, internal hernias, and obstruction [41,42]. (See 'Roux-en-Y gastric bypass' above.)

GASTRIC PLICATION — Gastric plication involves folding or imbricating the stomach along the greater curvature after the greater curve vessels have been divided. The normal postprocedure appearance on upper gastrointestinal (UGI) series is similar to that of a sleeve gastrectomy (SG), while the endoscopic appearance shows gastric folds created by the plication, similar to the endoscopic findings after gastric plication for reflux (image 37 and picture 6). In a series of 24 patients undergoing greater curvature plication, a multilobular intraluminal defect was identified in most patients [43].

SOCIETY GUIDELINE LINKS — Links to society and government-sponsored guidelines from selected countries and regions around the world are provided separately. (See "Society guideline links: Bariatric surgery".)

SUMMARY AND RECOMMENDATIONS

●Indications for imaging studies after bariatric surgery – For bariatric surgery patients who present with complaints of heartburn, nausea or vomiting, abdominal pain, or weight loss failure, radiographic imaging studies should be obtained to ensure prompt diagnosis of infection, obstruction, ischemia, or mechanical or technical failures of an operation. (See 'Introduction' above.)

●Role of imaging versus endoscopy – Radiologic evaluation and endoscopy are complementary studies, and endoscopy is often necessary for diagnostic certainty in bariatric patients with postoperative complications. Usually, imaging is performed first, and then a decision about proceeding to endoscopy is made based on the imaging findings and the patient's symptoms. (See 'The role of imaging after bariatric surgery' above.)

●Gastric banding – For patients who have complications after gastric banding, a plain abdominal radiograph with posteroanterior and oblique views and an esophagram with Gastrografin will provide the most useful diagnostic information. Most complications of gastric banding are due to a band that is too tight or gastric prolapse. (See 'Gastric banding' above and "Bariatric operations: Late complications with subacute presentations", section on 'Adjustable gastric banding'.)

●Gastric bypass – For patients who have complications after Roux-en-Y gastric bypass, the evaluation is guided by the patient's symptoms and whether these arise in the early postoperative period (within 30 days after surgery) or later. Early complications, such as leaks, can generally be identified on an upper gastrointestinal (UGI) series and/or CT of the abdomen and pelvis. However, reexploration may be necessary without definitive imaging if a leak is suspected clinically and the patient is too large for the CT scanner or for adequate radiologic penetration on UGI. For later complications, such as obstruction, an abdominal x-ray and a CT of the abdomen and pelvis will provide the most useful information. Upper endoscopy may also be necessary if indicated by imaging findings or based on the patient's symptoms. (See 'Roux-en-Y gastric bypass' above and "Bariatric operations: Late complications with subacute presentations", section on 'Roux-en-Y gastric bypass' and "Gastrointestinal endoscopy in patients who have undergone bariatric surgery", section on 'Roux-en-Y gastric bypass'.)

●Sleeve gastrectomy – For patients who have complications following sleeve gastrectomy, a limited UGI series and an endoscopy will usually identify the common underlying problems, such as dilation or stricture of the sleeve. (See 'Sleeve gastrectomy' above and "Gastrointestinal endoscopy in patients who have undergone bariatric surgery", section on 'Sleeve gastrectomy' and "Bariatric operations: Late complications with subacute presentations", section on 'Sleeve gastrectomy'.)

●Biliopancreatic diversion – A biliopancreatic diversion (BPD) with or without duodenal switch (DS) consists of a partial gastrectomy, which is essentially a sleeve gastrectomy (SG), along with a bypass procedure. Thus, the complications and diagnostic strategies are similar to those after SG and gastric bypass. (See 'Biliopancreatic diversion (BPD) with or without duodenal switch (DS)' above and "Bariatric operations: Late complications with subacute presentations", section on 'Biliopancreatic diversion and duodenal switch'.)