Dr. Behr is a Clinical Fellow, Abdominal Imaging/Nuclear Medicine, and Dr. Westphalen is an Assistant Professor of Radiology, Department of Radiology, University of California, San Francisco, CA; and Dr. Campos is the Associate Professor of Surgery, Department of Surgery, University of Wisconsin, Madison, WI.
are facing a health crisis: obesity. More than 100 million people in
the United States are defined as obese, 12 million of whom have extreme
(formerly morbid) obesity.1 Obesity is defined as a body mass
index (BMI, calculated as weight in kilograms divided by height in
square meters) >30, and extreme (morbid) obesity as a BMI >40 or
BMI >35 with a significant obesity-associated comorbidity. Common
serious comorbidities associated with obesity include type 2 diabetes
mellitus and hypertension. These patients also have a higher risk for
some types of cancer and early mortality. It is estimated that the
direct and indirect costs of treating obesity and its complications
exceed $75 billion per year.2
such as medications, exercise, and diet modifications, do not usually
provide longstanding results; thus, bariatric surgery has become a
well-accepted treatment option. The exponential increase in the number
of bariatric operations performed is the result of 4 factors: the
obesity epidemic, recognition of obesity as a public health problem,
poor results of nonsurgical methods, and reproducible good results with
surgery, including laparoscopic surgical techniques. However, bariatric
surgery should be offered only after careful preoperative evaluation and
counseling; it is often reserved for patients with extreme obesity and a
high risk for physical disability that severely impairs quality of
Surgeries achieve weight loss by physically changing the
patient’s upper gastrointestinal anatomy and physiology. The most common
procedures used in the United States are laparoscopic gastric banding
(LB, a restrictive procedure) and laparoscopic Roux-en-Y gastric bypass
(RYGB, a combination of restrictive and malabsorptive procedures). In a
very few centers, a procedure called the biliopancreatic diversion with
duodenal switch (BPD-DS, a malabsorptive procedure) is still used.
Despite the high safety profile of these procedures, with complication
rates on par with laparoscopic cholecystectomy, the radiologist must be
familiar with the typical postoperative appearances and be aware of
Each procedure is prone to different
complications. The most common complications of RYGB are wound infection
(6% to 13% of cases) and gastrojejunal anastomotic stricture (3% to
8%). However, patients are also at risk for postoperative bleeding (1%
to 4%), readmission for dehydration (1%), small-bowel obstruction (1%),
enteric leak (0.3% to 5%), pulmonary embolism (0.3% to 1%), and death
(0.1% to 1%).3-8 Patients who undergo LB may develop
device-related complications (10%), esophageal or gastric pouch dilation
(2% to 5%), band erosion into the stomach (2%), gastric slippage (4% to
6%), pulmonary embolism (0.1%), and death (0.1% to 0.4%).5
While most experts consider RYGB to be a more complex procedure, the
procedure has complication rates as low as LB when performed by properly
trained surgeons in high-volume institutions on properly selected
This article focuses on the imaging
of normal postsurgical anatomy and procedure-specific complications.
However, complications inherent to any surgery, such as pulmonary
embolism, infection, and hemorrhage, should always be considered when
evaluating these patients.
Roux-en-Y gastric bypass
The Roux-en-Y (RYGB) gastric bypass is
the most common bariatric procedure (70%) and among the most successful
(Figure 1). It is mostly a restrictive procedure, but it also has a
malabsorption component, as it bypasses most of the stomach, duodenum
and proximal jejunum. The procedure uses linear staplers to create a
small, 20- to 30-cc gastric pouch just past the gastroesophageal
junction. The gastric pouch should be completely isolated from the
larger excluded stomach. The jejunum is then divided approximately 30 to
50 cm beyond the ligament of Treitz, and the distal segment of jejunum
(alimentary limb) is brought up in either an antecolic (most common
nowadays) or retrocolic fashion and reattached to the small gastric
pouch (gastrojejunostomy). There are many techniques for the
gastrojejunostomy (handsewn, linear, or circular stapler), but it is
usually a small, 1- to 2-cm, end-to-side anastomosis. The excluded
stomach and duodenum, along with the 50 cm length from the proximal
jejunum after the ligament of Treitz (bilio-pancreatic limb), are then
reattached to the gastrointestinal tract about 75 to 150 cm from the
gastro-jejunostomy by a side-to-side
some have questioned the value of routine imaging, in many institutions
an upper-gastrointestinal (UGI) fluoroscopic exam is performed 1 or 2
days postoperatively (Figure 2). The goal of this study is to assess
leakage, pouch size, stoma size, pouch emptying, gastro-gastric
communication, and jejunojejunal anastomosis patency. Contrast should be
seen passing through both the proximal and distal anastomoses; however,
it is not unusual for the pouch not to empty readily due to edema
and/or a hematoma at the gastrojejunostomy. Computed tomography (CT) can
also be utilized to verify proper functioning of the RYGB bypass
(Figure 3). Contrast should not be identified in the excluded stomach
and duodenum. Reflux of contrast into the bilio-pancreatic limb may
reflect postoperative ileus or obstruction distal to the jejunojejunal
Although most surgeons agree that a small gastric
pouch is essential for long-term success, the exact size is
controversial. Nishie et al15 stated that different pouch
sizes did not have any short-term effects on weight loss. However,
Campos et al reviewed 361 patients and found that larger pouch size is
an independent predictor of poor weight loss.16 Pouch size is
difficult to quantify during the UGI examination, but a good rule of
thumb is for the pouch to be no bigger than the adjacent vertebral body.
Potential complications specific to RYGB
Anastomotic or staple leaks—The perioperative mortality of RYGB should not be more than 0.3%.17 The major risk factors are anastomotic leaks with peritonitis (75%) and pulmonary embolism (25%).17 Extraluminal leak occurs in approximately 1% of cases18-22
and can be seen anywhere along the divided GI tract, but also in the
distal esophagus (Figure 4). It is important to recognize these leaks,
as fever and abdominal pain may result from myriad postoperative
gastrogastric fistula is a communication between the proximal gastric
pouch and the excluded stomach, anywhere along the divided segment of
the stomach wall, but usually on the most superior aspect to the gastric
pouch (Figure 5). It occurs in approximately 6% of cases.23
Patients may present with epigastric pain from ulcerations along the
anastomotic site. Conservative management with proton-pump inhibitors
can be used, as long as symptoms resolve and weight loss is not
affected; otherwise the fistula should be corrected by nonemergent
Anastomotic stricture—The surgically
created gastrojejunostomy stoma usually has a diameter of approximately 1
to 2 cm, yet stenosis can occur. Patients usually present with the
inability to advance diet and/or persistent vomiting. Anastomotic
strictures can be divided into acute and subacute/chronic types. Early
postoperative stricture is in the vast majority of cases the result of
hematoma and/or edema; and it usually subsides within a week or 2. The
subacute type usually presents at 3 to 4 weeks after surgery and is
associated with ischemia, stomal ulcers, and fibrosis at the
gastro-jejunostomy. Rarely, strictures may have a later onset, sometimes
many months after surgery. Stomal stenosis occurs in about 5% of cases.
Treatment with balloon dilatation by endoscopy is successful in most
Other known complications—Small-bowel obstruction (SBO) occurs in approximately 1% to 4 % of cases after RYGB.19,21,24
It can be seen early in the postoperative period, but more frequently
it is seen later, once the patient has lost a significant amount of
weight. Early obstructions are usually of the biliary or alimentary limb
and related to postoperative edema, intra-luminal or intramural
hematoma, adhesions or “kinking” at the jejunojejunal anastomosis
(Figure 6). Obstruction late in the postoperative period differs in the
frequency of etiology, depending on whether the patient has had open or
laparoscopic RYGB. Adhesions are more often related to open RYGB and
internal hernias to a laparoscopic RYGB. Internal hernias seem to occur
more frequently if the alimentary limb was connected to the gastric
pouch using a retrocolic route instead of an antecolic route. In a
retrocolic approach, the surgeon has to create an opening in the
transverse mesocolon to bring the alimentary jejunal limb to the upper
abdomen. In the antecolic approach, though there is no opening in the
transverse mesocolon, there is a space in between the alimentary jejunal
limb and the transverse colon itself that is a potential site for an
internal hernia called
Petersen’s Hernia. A common site for internal hernias in both the
retrocolic and antecolic approaches is the jejunojejunostomy defect.25
Internal hernias should be expeditiously treated with surgery as they
are commonly associated with mesenteric torsion and bowel ischemia.
Other infrequent complications are intussusception,26 portal and mesenteric vein thrombosis27 (Figure 7), and bowel ischemia28 (Figure 8), among others.
Adjustable gastric banding
is one of the least invasive of the bariatric procedures; it is
performed in 27% of cases. An inflatable and adjustable band is
laparoscopically placed around the proximal stomach, about 4 to 5 cm
below the gastroesophageal junction (Figure 9). The location of the band
and size of the gastric pouch above the band can be determined
intraoperatively by using a balloon placed orally and inflated just past
the GE junction. The inner size of the band “stoma” is adjusted via a
subcutaneous port connected to the band by tubing and located in the
subcutaneous tissues. Unlike the case in RYGB, imaging is not routinely
performed postoperatively in banding. It is reserved instead for
patients with symptoms of obstruction or poor weight loss. Initial
fluoroscopic images look at the position of the band’s opening, which
should be at 45 to 90 degrees toward the right shoulder (Figure 10). The
band is examined in the right posterior oblique and anterior-posterior
views to assess the pouch and stoma size. The usual stomal diameter
should be between 5 and 10 mm and show adequate emptying.
2 most common complications related to gastric banding include pouch
enlargement and band/gastric slippage. The literature reports the
incidence of band/gastric slippage to be 1% and 22%.29-34 The
position of the band in relation to the gastric pouch is an important
determinant of the cause of pouch dilation, as there may be either an
anterior or posterior gastric wall migration through the band. Patients
usually present with acute symptoms and require emergent surgical
Conversely, pouch enlargement is considered when
there is nonobstructive dilation of the pouch with or without changes in
the angle of the band (Figure 11). This is considered a chronic
complication and surgery is reserved when conservative measures fail.
complications include band overinflation, band erosion into the
stomach, and port- and device-related infection/malfunction, among
others. Overinflation of the band can result in obstructive symptoms
with pseudoachalasia seen on UGI series (Figure 12). The reported
incidence of band erosion varies between 0% and 11% and may be related
to gastric wall injury during band placement or tight anterior fixation.35
On a UGI fluoroscopic exam, band erosion is evident by the presence of 2
channels of oral contrast, one through the band and another around it.
Port- and device-related complications include infection and
device breakdown. Infection can occur anywhere along the device or
intra-abdominally and is best evaluated by computed tomography (CT).
Port breakdown can be seen as discontinuous tubing on plain radiograph.
Sleeve gastrectomy, performed in only 3%
of cases, involves surgical resection of the greater curvature of the
body and fundus of the stomach to leave only about 15% of the original
gastric volume (60 to 100 cc), thus creating a restrictive physiology
(Figures 13 and 14). It is often performed on extremely obese patients
where the risks of a RGYB or duodenal switch (described below) are felt
to be too high. While in many centers it is used as a stand-alone
technique, it may be an element of a 2-part procedure in which patients
first undergo sleeve gastrectomy and later convert to an RYGB or
duodenal switch if the desired weight loss is not achieved.
complications associated with sleeve gastrectomy include leak,
hemorrhage, infection, and sleeve stricture/hematoma. Since sleeve
gastrectomy is a less common procedure, there is limited data concerning
complication rates. In a retrospective study by The Cleveland Clinic
Florida,36 there was only one instance of each major complication out of 137 cases.
the fluoroscopic UGI exam, close attention should be paid to the
gastric cut line for leak. Leak can occur anywhere along the surgical
line and may be seen in more than one location (Figure 15). Sleeve
stricture is seen in the chronic setting and is usually treated with
balloon dilation (Figure 16). Sleeve hematoma/edema is seen immediately
after surgery and is characterized on the fluoroscopic study as
obstruction of contrast through the stomach.
Biliopancreatic diversion with duodenal switch
This procedure involves creation of both
restrictive (sleeve gastrectomy) and malabsorption (duodenal switch)
physiologies (Figure 17). The duodenal switch consists of the division
of the small bowel at 2 points: (1) the duodenum, just distal to the
pylorus, and (2) the midjejunum (Figure 18). The most distal jejunum and
ileal loop are brought up to reconnect to the stomach and duodenum,
thus bypassing the biliary and pancreatic drainage. The excluded aspect
of the duodenum and jejunum is reattached to the distal portion of the
small bowel loop about 150 cm from the ileocecal valve to allow drainage
of biliary and pancreatic fluid. Unlike the classic RYGB, the pylorus
and first portion of the duodenum are preserved.
to the RYGB, both the proximal and distal aspects of the anastomoses
should be evaluated for leaks and passage of oral contrast during a
postoperative fluoroscopic exam. Careful evaluation of sleeve
gastrectomy and the duodenojejunal anastomoses should be performed for
anastomotic leak or delayed passage, which may be related to edema
and/or hematoma. Bowel obstruction is the most common complication, seen
in approximately 16% of the cases in one series.37 It is
most commonly seen at the proximal anastomosis and often resolves
spontaneously with bowel rest. Persistent or worsening symptoms should
trigger further evaluation for assessment of possible distal high-grade
small-bowel obstructions that may require surgical intervention (Figure
19). Anastomotic leak is the second most common complication, reported
to occur in approximately 5% of patients.37,38 In one series, the leak was reported to occur along the gastrectomy line in 70% of cases.37
is a significant public health problem that is on the rise; as more
obese children become obese adults, the diseases associated with it will
increase and more patients are likely to pursue bariatric surgery. It
is important that radiologists become active members of the
multidisciplinary team that manages these patients. And, for adequate
treatment and improved outcomes, it is crucial to have an understanding
of the normal postsurgical anatomy and procedure-specific complications.
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