CLINICAL & BASIC RESEARCH

SQU Med J, December 2010, Vol. 10, Iss. 3, pp. 354-360, Epub. 14th Nov 10  
Submitted 19th March 10
Revision ReQ. 15th June 10, Revision recd. 7th August 10
Accepted 15th August 10

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 490
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 14 22
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aBstract: Objectives: This study is a single institution retrospective evaluation of imaging findings of small bowel 
obstruction (SBO) after retrocolic antegastric Roux-en-Y gastric bypass surgery for morbid obesity. Methods: The 
radiological database of 490 patients who underwent gastric bypass surgery for morbid obesity from January 2001- 
2005 at the Royal Victoria Hospital McGill University Health Center was searched for SBO complications related to 
the procedure.  There were 22 cases of small bowel obstruction related to the procedure. Ten patients had abdominal 
and pelvic computed tomography (CT) scans, 12 patients had upper gastrointestinal (UGI) and small bowel follow 
through (SBFT). Results: Among 22 cases of SBO, 14 cases were due to anastomotic stenosis or adhesion, 7 due to 
internal hernia and one to jejuno-jejunal intussusception.  Among the 14 patients with SBO related to adhesion and 
anastomotic narrowing, 11 patients were managed medically and 3 cases managed surgically. CT scans correctly 
diagnosed 4 out of 5 cases including the 3 patients managed surgically and UGI and SBFT examinations diagnosed 
the remaining 9 cases that were managed medically. Among the 7 patients with internal hernias, CT scans correctly 
diagnosed 2 out of 4 cases, while UGI and SBFT examinations correctly diagnosed 1 out of 3. The jejuno-jejunal 
intussusception was correctly diagnosed by CT scan. Conclusion: The most frequent cause of SBO is anastomotic 
narrowing or adhesion. CT scan remains the most appropriate imaging modality in diagnosing acute presentation 
of SBO caused by internal hernia or adhesion/anastomotic narrowing. UGI and SBFT appear more appropriate for 
diagnosing the subacute insidious presentation of adhesive partial SBO.

Keywords:  Gastric bypass surgery; Small bowel obstruction; Morbid obesity; Anastomotic narrowing

Imaging of Small Bowel Obstruction following 
Gastric Bypass Surgery for Morbid Obesity

A retrospective review 
*Rashid Al-Sukaiti,1 Lawrence Stein,2 Nicholas Christou,2 Benoit Mesurolle,2 Giovanni P Artho2

CLINICAL & BASIC RESEARCH

1Department of Radiology and Molecular Imaging, Sultan Qaboos University Hospital, Muscat, Oman; 2Royal Victoria Hospital, 
Department of Diagnostic Radiology and Surgery, McGill University Health Center, Montreal, Canada. 
*Corresponding Author email: rsketty@hotmail.com



Rashid Al-Sukaiti, Lawrence Stein, Nicholas Christou, Benoit Mesurolle and Giovanni P Artho

Clinical and Basic Research | 355

Obesity has recently increased in prevalence and severity throughout the world, particularly in North America, 
and it has become a leading worldwide health 
concern.1-3 Patients who have a body mass index 
(BMI) of 18.5–24.9 kg per m2 are considered 
normal, while those with a BMI equal to or more 
than 30 kg per m2 are obese. Currently for those 
patients with intractable morbid obesity, defined 
as having a BMI of more than 40 kg per m2, 
gastric bypass surgery offers the only option for 
achieving meaningful and sustainable weight 
loss.3-5 Even dietary therapy together with exercise, 
pharmacological and behavioural therapy is rarely 
successful in these patients.1,3,4 The gastric bypass 
technique was introduced by Mason and Ito in 1967.6    
In 1994, Wittgrove et al. described the laparoscopic 
approach widely employed today.7 The Roux Y-limb 
gastric bypass surgery is currently considered the 
main treatment option in patients with intractable 
morbid obesity as it combines both restrictive and 
malabsorption approaches.1,4,5,8,9 The Roux Y-limb 
gastric bypass surgery can be performed either 
by the open or laparoscopic method, with the 
laparoscopic approach being preferred as it lowers 
the risk of wound related complications, and has 
the advantages of shorter hospitalisation and faster 
recovery. The Roux Y-limb procedure involves the 
creation of a gastric pouch. The small bowel is 
transected at about 45 cm distal to the ligament 
of Treitz, and 75 cm below this transection a side 
to side anastomosis is created between the Roux-
en-Y and the pancreaticobiliary limb. The Roux-
en-Y limb is either antegastric or retrogastric and 
is anastomosed to the gastric pouch via a retrocolic 
or antecolic approach.10 The main procedure at our 
institution is the retrocolic, antegastric approach 
[Figures 1 and Figures 2 a & b].  

Imaging is crucial in the work-up of complications 
related to this procedure including anastomotic 
leaks, bowel obstruction, abscesses, fistulas and 

haematomas.11 It also plays an important role in the 
diagnosis of small bowel obstruction which could 
be due to adhesions or an internal hernia.11 Blacher 
et al.11 reported on 23 patients with small bowel 
obstruction following laparoscopic Roux-en-Y 
limb gastric bypass surgery using the antegastric 
retrocolic approach.  Fourteen patients had internal 
hernias, while the remaining nine patients had small 
bowel obstruction due to adhesions. The prevalence 
of small bowel obstruction due to internal hernia 
was higher in Blacher et al.'s study as compared to 
our series,11 a complication that appears to be more 
common with the laparoscopic approach. 

The aim of this study was therefore to evaluate 
imaging findings of small bowel obstruction (SBO) 
after retrocolic antegastric Roux-en-Y gastric bypass 
surgery for morbid obesity.

Methods
Following approval by the institutional Review 
Board, the radiological and surgical databases of 490 
patients, who underwent gastric bypass surgery for 
morbid obesity at our institution from 2001-2005, 
were searched for SBO complications related to the 
procedure. Given the retrospective nature of the 
study, the requirement for informed consent was 
waived. There had been increase in the numbers 
of gastric bypass cases performed laparoscopically 
at our institution since October 2003. Therefore 
there were a total of 273 patients who underwent 
gastric bypass by the laparoscopic approach while 
the remaining 217 had the open approach. Among 
the 490 patients, there were 22 cases of small 
bowel obstruction (SBO). Among the 22 cases 
of SBO, 10 patients had computed tomography 
(CT) scans, 12 patients had upper gastrointestinal 
(UGI) examinations and one patient had both UGI 
and CT. The imaging findings were reviewed by 
two abdominal radiologists in consensus, and the 
clinical characteristics were reported according to 

Advances in Knowledge 
1. This study showed the importance of being familiar with the approach of gastric bypass surgery performed in order to assist in  

interpreting imaging findings of small bowel obstruction following  retrocolic antegastric Roux-en-Y gastric bypass surgery for morbid 
obesity.

Application to Patient Care
1. This study showed the importance of prompt diagnosis of causes of small bowel obstruction in morbid obese patients who have 

undergone retrocolic antegastric Roux-en-Y gastric bypass surgery. Physicians should take this into account in order to achieve better 
patient management.



Imaging of Small Bowel Obstruction following Gastric Bypass Surgery for Morbid Obesity 
A retrospective review 

356 | SQU Medical Journal, December 2010, Volume 10, Issue 3

the time after surgical management of SBO. The 
imaging findings were recorded and compared 
to the surgical findings, when applicable, and to 
the literature. All CT scans were performed with 
either a 4 or 16 slice General Electric scanner (GE 
Healthcare) with preference being given to a 16 
slice CT scan whenever available. Patients received 
125 ml of Optiray 350 which was administered at a 
rate of 2–3 ml per second with a power injector. In 
patients who were suspected to have an anastomotic 
leak immediately postoperatively, UGI and small 
bowel follow through (SBFT) examinations were 
performed using water soluble contrast. Rapid 

sequence images of gastrojejunal anastomosis 
were obtained in different projections. Overhead 
radiographs were obtained at 15–20 minute 
intervals until contrast opacified the jejunojejunal 
anastomosis. In patients who presented beyond 
the immediate postoperative period, and in whom 
anastomotic leaks were not suspected, UGI and 
SBFT examinations were performed using thin 
barium; overhead radiographs were obtained 
following fluoroscopic examination at 15–20 
minutes.

Results
Imaging findings were reviewed retrospectively by 
two abdominal radiologists who were blinded to the 
level and cause of the SBO. There were 22 cases of 
SBO: 14 cases were due to anastomotic narrowing/
adhesions; there were 7 cases of internal hernia (3 
of them were at transverse mesocolon defect and 4 
were at small bowel mesentry defect) and one case of 
jejuno-jejunal intussusception. No Peterson hernia 
was encountered [Table 1]. The mean time from 
Roux-en-Y gastric bypass surgery to the diagnosis 
of adhesive small bowel obstruction was 100 days, 
while that due to internal hernia was 255 days mean.  
In 10 out of 22 patients the presentation was acute 
with the most common presenting symptoms being 
abdominal pain, vomiting, and distention. These 
patients underwent a CT scan. In the remaining 12 
cases, the presentation was subacute with insidious 
onset of intermittent postprandial abdominal pain 
and nausea. These patients underwent UGI and 

Figure 1: Gastric bypass surgery using antegastric, 
retrocolic approach. 1) Gastric pouch; 2) excluded 
stomach; 3) Roux limb; 4) pancreaticobiliary limb; 
Gastrojejunal anastomosis (thin arrow); (thick arrow)  
ejuno-jejunal anastomosis.

Figures 2a & b: Fluoroscopic spot image obtained at upper gastrointestinal examination showing a normal 
postoperative anatomy following a  gastric bypass procedure. 1) gastric pouch; 2) side to side gastrojejunal 
anastomosis; 3) Roux limb ; 4) pancreaticobiliary limb; 5) side to side anastomosis between pancreaticobiliary limb, 
and Roux limb.



Rashid Al-Sukaiti, Lawrence Stein, Nicholas Christou, Benoit Mesurolle and Giovanni P Artho

Clinical and Basic Research | 357

SBFT exams. Seven of these cases were due to 
internal hernia, three due to adhesion, while one 
case was due to jejuno-jejunal intussusception.  The 
remaining 11 cases of presumed partial small bowel 
obstruction were managed conservatively [Table 2]. 
Among the adhesive small bowel obstructions, 13 
cases were obstruction at jejuno-jejunal anastomosis 
and most cases were managed conservatively except 
for two cases that required surgical management. 
There was one case of adhesive SBO at transverse 
mesocolon that was managed surgically. Among 
surgically managed SBO, UGI correctly diagnosed 
one of three internal hernias, one case was labelled 
incorrectly as adhesion, and one case was equivocal. 
While one case of adhesive SBO was correctly 
diagnosed using UGI, CT correctly diagnosed 2 of 
the 4 internal hernias, 2 of the 3 adhesions, and one 
case of jejuno-jejunal intussusception. Among the 
medically managed partial SBO, 9 cases out of 11 
were diagnosed using UGI and two cases using CT.

In two of the four cases of small bowel mesentry 
internal hernia, there was herniation of both the 
Roux-en-Y and pancreaticobiliary limb, while the 
remaining two cases had herniation of the Roux-
en-Y limb only. Among the 7 patients with internal 
hernia, 5 had a laparoscopic approach and 2 had 
the open approach. Among the 14 patients with 
adhesive/anastomotic narrowing SBO, 7 had the 
laparoscopic approach and the remaining 7 had the 
open approach.

Discussion
The interpretation of SBO imaging findings 
following gastric bypass surgery can be challenging 

Figure 3: Potential sites of small bowel internal hernia 
following gastric bypass surgery are: 1) transverse 
mesocolon defect; 2) Roux-en-Y Limb mesentry, and 3) 
distal jejuno-jejunal mesentry. Figure 4: Contrast enhanced image of the upper 

gastrointestinal tract demonstrates significant 
dilatation of the Roux limb (thin white arrow) 
with delay in passage of contrast at the level of the 
transverse mesocolon defect (thick white arrow). 
Surgery revealed SBO at the transverse mesocolon 
defect due to adhesion.

Figures 5a, b & c: Small obstruction caused by internal hernia at transverse mesocolon defect.  5a & b: transverse 
computed tomography (CT) images show dilated Roux-en-Y Limb (arrow) anteromedial to excluded stomach(s). 5c: 
transverse CT images show cluster of small bowel loops against the mid-abdominal wall with no overlying omentum 
and displacement of the transverse colon (curved arrow) posterocentrally.



Imaging of Small Bowel Obstruction following Gastric Bypass Surgery for Morbid Obesity 
A retrospective review 

358 | SQU Medical Journal, December 2010, Volume 10, Issue 3

for the radiologist. Usually, these patients present 
with symptoms of abdominal pain, nausea and 
vomiting which are nonspecific in such patients. 
Imaging can play an important role in classifying 
SBO according to level of  obstruction and cause 
(i.e. adhesion or internal hernia) [Figure 3]. In order 
to interpret the imaging findings, the radiologist 
has to be familiar with the gastric bypass surgery 
approach performed at his institution. We have 
reported our experience of SBO imaging findings 
following retrocolic antegastric Roux-en-Y gastric 
bypass surgery.  The incidence of SBO in our series 
was 4% which is similar to the rates reported in the 
literature.10-14  

Small bowel obstruction following gastric bypass 
surgery is mainly due to adhesions or anastomotic 
stenosis. Internal hernias occur to a lesser extent 
and intussusception is rarely a cause.11,15 Small 
bowel obstruction due to anastomotic narrowing 
or adhesion occurs in the gastrojejunal or 

jejunojejunal anastomotic region. In our series, 13 
cases out of 14 had obstruction at jejunojejunal 
anastomosis, and one case had obstruction at 
gastrojejunal anastomosis. The imaging findings 
on UGI and CT varied between abrupt angulation 
from a dilated proximal bowel loop to a collapsed 
distal loop and delay in passage of contrast beyond 
the transition point on UGI [Figure 4]. Potential 
sites for internal hernia following gastric bypass 
surgery are transverse mesocolon defect, small 
bowel mesentery defect and the space behind the 
Roux limb.16 In our series, 7 out of 22 (32%) cases 
presented with internal hernias, 3 of them were 

Figures 6a & b: Small bowel obstruction caused by internal hernia at the jejunal mesenteric defect. 6a: Transverse 
computed tomography (CT) images show significant dilatation of the excluded stomach(s). 6b: Transverse CT images 
show significant dilatation of the pancreaticobiliary and Roux limbs with a cluster of these bowel loops lying against 
the left abdominal wall with no overlying omentum.
Legend: ES = Excluded stomach; PBL = pancreaticobiliary limb; RL = Roux-en-Y limb

Table 1: Level and cause of small bowel obstruction in 22 
patients following Roux-en-Y gastric bypass surgery

Gastrojejunal 
anastomosis  

Jejunojejunal 
anastomosis

Adhesion 1 13

Internal hernia 3 4

Intussusception 0 1

Table 2: Management of 22 cases of small bowel 
obstruction following Roux-en-Y gastric bypass surgery 

Surgical 
Management 

Conservative 
Management

Adhesion GJ 
anastomosis   

1 0

Internal hernia 
GJ anastomosis 

3 0

Adhesion at J-J 
anastomosis 

2 11

Internal hernia at 
J-J anastomosis 

4 0

Intussusception 
at J-J anastomosis

1 0

GJ = gastrojejunal; J-J = jejuno-jejunal 



Rashid Al-Sukaiti, Lawrence Stein, Nicholas Christou, Benoit Mesurolle and Giovanni P Artho

Clinical and Basic Research | 359

internal hernias at transverse mesocolon defect and 
4 were at small bowel mesentry defect. A possible 
predisposing factor for developing internal hernia 
in these patients is rapid massive weight reduction 
which results in decrease intraperitoneal fat that 
may enlarge the mesenteric defect.11 Since the Roux-
en-Y limb is anastomosed to the gastric pouch in a 
retrocolic, antegastric approach at our institution, 
the CT imaging findings of internal hernia through 
the transverse mesocolon defect were a cluster 
of small bowel loops lying anterior to the body of 
excluded stomach and against the mid-abdominal 
wall with no overlying omentum. In addition, there 
was displacement of transverse colon dorsally and 
centrally [Figures 5 a, b & c].17

In the case of small bowel mesenteric hernias, the 
CT imaging findings were a cluster of small bowel 
loops against left abdominal wall with no overlying 
omentum and posteromedial displacement of the 
descending colon.11,17 In two of the four cases of 
internal hernia through the small bowel mesentry 
defect, there was herniation of both the Roux-en 
Y and pancreaticobiliary limb which resulted in 
dilatation of both limbs and the gastric remnant 
[Figures 6 a & b ].

In our series, we did not encounter a case 
of Peterson hernia. Intussusception is very rare 
following gastric bypass surgery, with few reported 
cases.11,15,18 In our series, we had one case that 
presented with jejuno-jejunal intussusception that 
required emergency exploratory laparotomy. The 

diagnosis was made via a CT scan, the imaging 
findings were a target like appearance with 
invagination of mesenteric fat and vessels in the 
intussuscipiens [Figure 7].

Conclusion
The most frequent cause of SBO following gastric 
bypass surgery is anastomotic narrowing or 
adhesions. CT scan remains the most appropriate 
imaging modality in diagnosing acute presentations 
of SBO caused by internal hernias or adhesions. UGI 
and SBFT appear more appropriate in diagnosing 
the subacute insidious presentation of adhesive 
or anastomotic narrowing of a partial SBO. While 
small bowel obstruction following gastric bypass 
surgery may represent a diagnostic challenge to 
the radiologist, the knowledge of surgical approach 
and clinical presentation will help in identifying the 
level and cause of SBO, thus helping in operative 
planning. 

c o n f l i c t o f i n t e r e s t
The authors reported no conflict of interest.

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