Dr. Mitchell is a Radiologist, Department of Radiology,
Advocate Christ Medical Center, Oak Lawn, IL. At the time this article
was submitted for publication, she was an Associate Professor in the
Department of Radiology at the University of Chicago, Chicago, IL.
has quite literally become a growing national health problem of immense
proportions. The body mass index (BMI) is a parameter used to assess
obesity and is calculated by dividing the patient’s weight by the square
of the patient’s height. The National Institutes of Health (NIH)
classiﬁes patients as overweight with a BMI of 25 to 30 kg/m2, as obese with a BMI of ≥30 kg/m2, and as extremely (morbidly) obese with a BMI of ≥40 kg/m2.1 The
NIH estimates that the prevalence of obesity in adults was only 10.4%
in men and 15.1% in women for the period of 1960 to 1962.1 The
prevalence of overweight and obese people has been steadily increasing
during the last several decades. The age-adjusted prevalence of
overweight adults in 1999 to 2000 was 64.5% compared with 55.9% in 1988
to 1994. The prevalence of obesity for the same groups was 30.5%
compared with 22.9%, while the prevalence of extreme obesity has gone
from 2.9% to 4.7%.2 Nonsurgical methods of weight loss, such
as behavior modiﬁcation and pharmacologic agents, are not effective in
maintaining clinically signiﬁcant weight loss for >5 years in
patients who are morbidly obese.3 In these patients, bariatric surgery is more effective for weight loss and for the control of some comorbid conditions.4,5
surgical procedures typically consist of a restrictive component with
or without a malabsorptive component to achieve weight loss. There are 3
bariatric surgical procedures in common use today: Roux-en-Y gastric
bypass (RYGB) surgery, duodenal switch (DS) with pancreaticobiliary
diversion surgery, and laparoscopic adjustable gastric banding (LAGB).
Radiologic assessment of these procedures is often done in the immediate
postoperative period to conﬁrm that the postsurgical anatomy is intact.
In addition, imaging is frequently requested by the surgeon when
complications are suspected. A good understanding of the postsurgical
anatomy and of the appearance of complications is essential for accurate
interpretation of these studies.
technical settings and protocols are usually inadequate for imaging the
morbidly obese patient. For ﬂuoroscopic examinations, we use only
digital imaging, as analog systems do not penetrate the patients’ bodies
sufﬁciently. Water-soluble contrast medium is preferable for a few
reasons. It is sufﬁciently opaque to provide diagnostic information, but
is sufﬁciently lucent to avoid inadequate beam penetration in these
large patients. Most clinical questions concern the proximal anatomy, so
dilutional effects are not an issue. In addition, the more common
postoperative complications include anastomotic leak with extravasation
into the peritoneal cavity. If the main concern is for signiﬁcant
obstruction without leak, low-density barium can be used. Contrast is
administered orally in small increments or in patient-controlled
swallows during ﬂuoroscopic observation. A total of 100 mL of oral
contrast is usually adequate. Ideally, the patient should be imaged
supine and upright and assessed in frontal, lateral, and oblique
projections; however, the reality is that many of these patients are too
large for any imaging other than in a standing anteroposterior
Computed tomography (CT) examinations also require
technical modiﬁcations to penetrate these patients. The kVp should be
increased to 140, and mAs should be increased to 300 to 400 with manual
settings. The scan protocol should use oral and intravenous (IV)
contrast as indicated by the clinical question. Increasing the dose of
IV contrast by 10% to 20% may improve contrast enhancement.
Roux-en-Y gastric bypass surgery
Laparoscopic RYGB was ﬁrst reported in 1994 by Wittgrove et al.6 The
procedure involved the creation of a small gastric pouch with a volume
of 20 mL, which is isolated from the remainder of the stomach. This is
the restrictive component of the procedure and is the main factor in
weight loss. The jejunum is divided 10 to 15 cm distal to the ligament
of Treitz, and a 100-cm Roux-en-Y is created that is brought up through
the transverse mesocolon and anastomosed to the gastric pouch. This
alimentary limb is the malabsorptive component of the procedure and is a
secondary contributor to weight loss (Figure 1).
ﬂuoroscopy, contrast should pass easily from the esophagus into a small
gastric pouch approximately 3 to 4 cm in diameter and should then ﬂow
easily into the Roux limb. The Roux limb will have a jejunal mucosal
fold pattern and will descend in the left abdomen (Figure 2). If the
anastomosis between the gastric pouch is end-to-side, a small blind
stump of bowel will be seen that should not be confused with an
anastomotic leak. The length of the remaining small bowel is only
slightly less than in normal patients.
that are diagnosed radiographically have been estimated to occur in 10%
of patients. The most common complications encountered with RYGB are
anastomotic leaks and anastomotic stenoses, both of which more commonly
involve the proximal anastomosis.7 A leak is diagnosed by the
identiﬁcation of contrast extravasation at the anastomosis. The leak
will be intraperitoneal if the pouch was separated from the remainder of
the stomach (Figure 3). If the stomach was not transected at the suture
line, a leak may occur along the staple line and will opacify the
excluded stomach (Figure 4). A stenosis appears as a narrowing of the
anastomosis. In the immediate postoperative period, these stenoses are
usually caused by edema and are self-limiting. A stenosis in the later
postoperative period is more likely to be caused by ﬁbrotic strictures
(Figures 4 and 5).
Atypical complications of RYGB are much less frequent.8 Anastomotic
leaks may resolve with conservative management; however, they may
occasionally progress to abscess formation or to the more rare
complication of enterocutaneous ﬁstula (Figure 6). Hernias are another
uncommon complication of RYGB and present with obstructive symptoms.
These can be internal hernias, particularly through the mesocolic defect
created during the surgery (Figure 7), and ventral hernias, often
through the incision sites. Misconstructions are rare complications that
are typically seen after surgical revisions, rather than after the
primary surgery. An antiperistaltic Roux limb inversion occurs when the
Roux limb is cut at both ends and is inadvertently re-anastomosed in an
inverted fashion. This results in retrograde peristalsis, and patients
will present with nausea, vomiting, and/or intolerance of food. The
anatomy will look normal on static images, but the Roux limb will show
reversed peristaltic activity during ﬂuoroscopic observation when
challenged with an adequate volume of contrast. Another rare
misconstruction is the “Roux-en-O,” in which the biliary limb is
inadvertently anastomosed to the gastric pouch, again resulting in an
antiperistaltic Roux limb conﬁguration. This diagnosis should be
considered in patients who present with bilious vomiting and chronic
malnutrition. Ulcers are another rare complication that are usually not
identiﬁable radiographically (Figure 8).
Duodenal switch with pancreaticobiliary diversion surgery
Duodenal switch with pancreaticobiliary diversion surgery was developed by Hess9 and Marceau et al10,11 in
the 1990s. The restrictive component of DS surgery is less severe than
in RYGB and consists of a pylorus-sparing vertical or sleeve gastrectomy
that excludes 70% to 80% of the stomach at the greater curvature. The
duodenum, jejunum, and proximal ileum are excluded from the stomach and
form the biliary limb. The ileum is transected, and a 250-cm Roux-en-Y
is brought up from the ileum rather than the jejunum and is anastomosed
to the pylorus. The anastomosis between the alimentary limb and the
biliary limb is 75 cm proximal to the ileocecal valve. Thus, the
malabsorptive component is the dominant factor in weight loss, as the
patient has only 325 cm of small bowel available for food absorption
(Figure 9). The DS procedure provides superior weight loss in
super-obese patients (BMI >50 kg/m2) compared with RYGB,
but its greater technical complexity and perceived perioperative and
nutritional risks have limited the widespread use of DS among bariatric
gastric pouch following DS is larger than that in RYGB (Figure 10). It
is tubular and runs the length of the lesser curvature. The pylorus is
identiﬁable in the epigastrium or the right upper quadrant and results
in intermittent emptying of the stomach. The alimentary limb will have
an ileal fold pattern and descends into the right abdomen. A Baker’s
pouch may be present. The length of the remaining small bowel that will
be opaciﬁed is much shorter than with RYGB.
that can be diagnosed radiographically occur in approximately 20% to
25% of patients. This is a higher incidence than with RYGB. The most
common complication following DS is bowel obstruction, the majority of
such cases are caused by anastomotic stenosis at the gastroenteric
anastomosis or in the gastric body. As with RYGB, these are commonly due
to edema in the immediate postoperative period. They can be due to
ﬁbrosis or adhesions when they occur later and may involve the gastric
body as well as the anastomosis (Figure 11). Anastomotic and suture line
leaks are less common than with RYGB, but they still occur and can
develop into abscesses (Figure 12). Hernias are also relatively common
complications and tend to be ventral more often than internal.
Symptomatic hiatal hernias are rare but can occur due to the acidity of
the gastroesophageal (GE) reﬂux in patients with DS surgery (Figure 13).
Hiatal hernias with RYGB are usually of little consequence, because the
gastric pouch lacks parietal cells. Other rare complications include
ulcers and enterocutaneous ﬁstulae.
Laparoscopic adjustable gastric banding
Laparoscopic adjustable gastric banding was ﬁrst introduced in 1993 as a less invasive bariatric surgical procedure.12 This
is a purely restrictive procedure that creates a small gastric pouch by
placing a band around the gastric cardia. Tubing connects the band to a
subcutaneous access port that can be used to inﬂate or deﬂate the band
as needed to control the patient’s food intake. This is a less effective
procedure for weight loss. It is used for moderately obese patients
(BMI <50 kg/m2) who do not have any major comorbid
conditions (such as diabetes) and who are able to adhere to a diet
regimen. Patients with a history of eating disorders are not candidates
for this procedure.13
gastric band is radiopaque and lies approximately 2 to 3 cm caudal to
the GE junction; its proximity to the GE junction varies with the
surgeon’s preference (Figure 14). It should form a 45˚to 55˚angle with
the spine. Connecting tubing will extend from the pouch to a
subcutaneous port placed in either the left anterior or the left lateral
abdominal wall. Upon upper gastrointestinal examination, the gastric
“stoma” at the level of the pouch is typically between 5 and 10 mm
(Figure 15). This diameter can be varied by inﬂating or deﬂating the
band with saline. The optimal diameter is determined by the patient’s
tolerance and rate of weight loss.
Several complications of LAGB have been described.13 Band
misplacement or displacement can be too high and on the esophagus, in
which case the reservoir function of a gastric pouch is lost and the
patient never has a feeling of satiety; or it can be too low on the
stomach, which results in pouch dilatation (Figure 16). The stoma can be
too tight, resulting in pouch dilatation (Figure 17); or too loose,
resulting in failure to lose weight. A less common cause of pouch
dilatation is gastric stricture at the level of the band. Tubing
disconnection can occur and usually requires surgical correction (Figure
18). The access port can rotate and invert within the abdominal wall,
which also may require surgical correction. Paragastric herniation of
the gastric cardia alongside the stomal segment is a rare complication
(Figure 19) that may be caused by a band position anomaly. This has not
yet been reported in the literature.
surgery is becoming increasingly popular for weight loss in morbidly
obese patients. A variety of procedures may be used. For proper
interpretation of imaging ﬁndings, it is essential that radiologists
know postsurgical anatomy prior to examination of these patients.
Functional abnormalities of motility may be occult on static imaging and
can be diagnosed only with careful ﬂuoroscopic assessment.
- Clinical Guidelines on the Identiﬁcation, Evaluation,
and Treatment of Overweight and Obesity in Adults: Evidence Report. National Institutes of Health publication no. 98-4083. Bethesda, MD:National Heart, Lung, and Blood Institute;1998.
- Flegal KM, Carroll MD, Ogden CL, et al. Prevalence and trends in obesity among US adults, 1999-2000. JAMA. 2002;288:1723-1727.
Institutes of Health Consensus Development Conference Panel.
Gastrointestinal surgery for severe obesity. Ann Intern Med.
- Maggard MA, Shugarman LR, Suttorp M, et al. Meta-analysis: Surgical treatment of obesity. Ann Intern Med. 2005;152:547-559.
- Buchwald H, Avidor Y, Braunwald E, et al. Bariatric surgery: A systematic review and meta-analysis. JAMA. 2004;292:1724-1737.
AC, Clark GW, Tremblay LJ. Laparoscopic gastric bypass Roux-en-Y:
Preliminary report of ﬁve cases. Obes Surg. 1994;4:353-357.
LR, Turner MA. Radiologic evaluation following Roux-en-Y gastric bypass
surgery for morbid obesity. Eur J Radiol. 2005;53:353-365.
MT, Pizzitola VJ, Knuttinen MG, et al. Atypical complications of
gastric bypass surgery. Eur J Radiol. 2005;53:366-373.
- Hess DS, Hess DW. Biliopancreatic diversion with a duodenal switch. Obes Surg. 1998;8:267-282.
- Marceau P, Hould FS, Simard S, et al. Biliopancreatic diversion with a duodenal switch. World J Surg. 1998;22:947-954.
- Prachand VN, Davee RT, Alverdy JC. Duodenal switch provides superior weight loss in the super-obese (BMI > or = 50 kg/m2) compared with gastric bypass. Ann Surg. 2006;244:611-619.
P, Hallberg D, Hellers G. Gastric banding for morbid obesity: Initial
experience with a new adjustable band. Obes Surg. 1993;3:369-374.
MJ, Birjawi G, Moukaddam HA, et al. Complications of adjustable gastric
banding: A radiological pictorial review.AJR Am J Roentgenol.