Phẫu Thuật Giảm Béo (Bariatric Surgery)

from less than 15 ml to over 500 ml in volume.5 These patients can pres-
ent with a constellation of symptoms including inappropriate weight loss,
epigastric pain, gastro-oesophageal reflux and intractable vomiting.
Based on the underlying cause, pouch dilatation can be described as
being: a) acute concentric; b) chronic concentric; or c) eccentric. Acute
concentric pouch dilatation occurs in patients with stomal stenosis
resulting from over-inflation of the balloon (Fig. 6). They present with
dysphagia and painful swallowing soon after band inflation. UGI shows a
dilated pouch with little or no passage of contrast material into the distal
stomach. Immediate radiological deflation of the balloon followed by sur-
gical referral is required for treatment.23 If the stenosis is relatively recent,
the stoma will reopen easily with immediate symptom relief. However, in
chronic pouch stenosis, peri-stomal fibrosis may prevent reopening and
device removal would be required for treatment.15
Imaging of Complications After Bariatric Surgery
233
Figure 5.
Oesophageal dilatation due to high band placement. Barium swallow exami-
nation showing marked dilatation of the oesophagus in spite of a patent and normal
gastro-oesophageal junction. This is often associated with poor motility and can show ter-
tiary contractions (arrows). This is particularly seen in bands placed too high with a small
pouch and can be very difficult to adjust.

Chronic concentric dilatation results from chronic ingestion of large
volumes of poorly masticated food. The stoma is open and of normal size
or slightly dilated, but there is overstretching of the gastric pouch from
chronic retention of poorly digested solid foods. UGI series will show
a markedly distended pouch with open stoma and passage of contrast
material into the distal stomach. Associated oesophageal dilatation and
gastro-oesophageal reflux are frequent findings. Treatment requires
dietary modification and patient education before return of the pouch to
normal size.5
Eccentric pouch dilatation occurs relatively commonly and is due to
either posterior or anterior band slip. This occurs as part of the ‘band
slip–hernia–pouch dilatation’ complex described below. Patients with this
complex present with food intolerance, vomiting and rapid weight loss.
During UGI assessment, the control film shows abnormal angulation of
the gastric band with a more horizontal lie that is suspicious of slippage.
On the frontal view, a pouch above and lateral to the band usually indi-
cates an anterior slip (Fig. 7), whilst a pouch below the band indicates a
posterior slip.24 This can easily be confirmed by lateral fluoroscopy that is
234
J. C. Varghese and S. H. Roy-Choudhury
Figure 6.
Acute concentric pouch dilatation following over-inflation of balloon. Dilute
barium swallow shows narrow stoma (arrow) with very little contrast passing through.
Note the moderately dilated proximal pouch, which is symmetrically dilated.

very helpful in the evaluation of patients with food intolerance where
band slippage is suspected. Emptying of the pouch is usually poor. If a
dilated pouch is seen, it is usual practice to immediately deflate the band
before urgent surgical referral.
Occasionally, an excess of anterior fundus may be above the band,
which may simulate a pouch (Fig. 8). The band angulation remains in
excess of 20° and the pouch empties spontaneously. Band adjustments are
difficult in these cases, but a policy of careful under-inflation with fre-
quent follow-up may be adopted for these unusual patients (Mr H. Kumar,
consultant surgeon, Birmingham, UK, pers. comm.).
Gastric herniation
Gastric herniation can be concentric or eccentric in nature. Concentric
gastric herniation occurs with an incidence of 1.8–5 per cent21,25 and
results from cephalad migration of the stomach through the band due
Imaging of Complications After Bariatric Surgery
235
Figure 7.
Eccentric pouch dilatation due to anterior band slippage. Dilute barium swal-
low shows posterior and lateral extension of pouch (white arrows) above the band typical
of eccentric pouch dilatation due to anterior slippage of band. Note the horizontal orienta-
tion of the band (between black arrows), probably due to the gastro-gastric sutures giving
way. There is very little of the administered contrast passing through the stoma, and the
oesophagus is moderately dilated (arrowheads).

to high pouch pressures ‘pulling’ gastric tissue up from below the
band. Eccentric gastric herniation usually occurs as part of the band
slip–hernia–pouch dilatation complex.24
Patients with gastric herniation can present with severe upper abdom-
inal pain, intractable vomiting and inability to swallow. On UGI series, a
constellation of findings including malpositioning of the silicone band,
eccentric pouch dilatation and partial or complete obstruction to outflow
of contrast material may be seen. Occasionally slippage may be associated
with a volvulus, where there is abnormal orientation of the stomach with
transposition of the greater curvature above the lesser curvature in the
organoaxial plane. Associated acute gastric obstruction is usual with
complete non-passage of contrast material into the distal stomach. These
findings constitute a surgical emergency that requires decompression of
236
J. C. Varghese and S. H. Roy-Choudhury
Figure 8.
Excess anterior fundus above band simulating appearance of a pouch. Dilute
barium swallow shows small redundant mucosa above the band due to gathering of ante-
rior fundus above the band (small arrows). This should be differentiated from an eccentric
pouch by the normal passage of barium through the band (between large arrows), and the
relatively normal band angulation.

the balloon by the radiologist and urgent surgical referral. Band relocation
with gastric reduction and surgical fixation is required for long-term
symptomatic relief.13
Gastric obstruction
In the early postoperative period, oesophageal obstruction can occur due
to inappropriate band size (e.g. small band in a super-obese patient) or
postoperative oedema.26,27 Passage of a nasogastric tube and conservative
treatment usually leads to symptom resolution with the latter.
In the late postoperative period, gastric obstruction can be caused by
a number of entities including over-tightening of the stoma and band slip-
page. Less common causes would include stomal obstruction from food
bolus (Fig. 9) or bezoar,28 and extrinsic compression from proximal axial
gastric herniation.13 In all these cases, UGI determination of band
Imaging of Complications After Bariatric Surgery
237
Figure 9.
Obstruction due to food impaction 11 months after band insertion. Dilute
barium swallow shows complete oesophageal obstruction at the level of the band in a
patient with acute onset dysphagia. Note the indentation at the stoma (arrow) due to an
obstructive food bolus. This was removed at endoscopy.

position, gastric orientation, pouch size, presence of any pouch filling
defects and stomal patency helps in establishing the presence and cause of
obstruction with a great deal of accuracy. CT with multiplanar
reconstructions can also be useful in confirmation of the diagnosis.
Gastric perforation
Gastric perforation is an infrequent perioperative complication that occurs
with an incidence of around 0.5 per cent, often related to deep suture bites
being taken during gastric mobilization and imbrication of the silicone
band.12 The commonest cause of leak during the late postoperative period
is from band erosion as described below. Finally, any cause of gastric
ischemia — such as acute gastric dilatation or volvulus — can lead to
necrosis and perforation. These are diagnosed by the finding of contrast
extravasation during UGI, or extraluminal fluid and gas on CT (Fig. 3).
Intra-abdominal haemorrhage
Intra-abdominal haemorrhage can be intra- or extra-gastric in location.
During the early postoperative period, extra-gastric haemorrhage results
from bleeding of perigastric blood vessels damaged during gastric mobi-
lization and prosthetic insertion.29 The bleeding is usually self-limiting
and asymptomatic. However, if the patient becomes haemodynamically
unstable, a CT can be performed to show acute haematoma or active
bleeding. Usually, blood transfusion and conservative measures are
sufficient for treatment.
During the late post-operative period, intragastric bleeding can be
related to the specific complication of gastric band erosion, where the band
erodes through blood vessels in the gastric wall.30 Depending on the degree
and acuity of vascular injury, the presentation can vary from chronic anaemia
to acute life threatening haematemesis. Emergency laparotomy with band
removal with cautery of bleeding vessels may be required for treatment.
Band complications
Band erosion
This is a late complication resulting from pressure necrosis of the gastric
wall leading to translocation of part or whole of the band into the gastric
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J. C. Varghese and S. H. Roy-Choudhury

lumen. It is seen in up to 11 per cent of cases (mean, 3 per cent), with a
time to presentation of 19–23 months.22,31 Patients present with slowing of
weight loss, or even weight gain. Even though the band has penetrated
through the gastric wall, there is rarely free intraperitoneal leak due to the
protracted nature of the process, allowing time for fibrosis and healing to
take place. A very characteristic presentation of band erosion is that of
port infection from tracking of infection along the tubing. In fact,
protracted access port infection is often the first sign of band erosion.30
Band erosions can occasionally present with severe life threatening
complications such as haematemesis,32 or gastric outlet obstruction.33,34
Yet it can also be completely asymptomatic and found incidentally at
endoscopy or barium assessment.30 The finding on UGI is pathognomonic
with contrast outlining the band seen as a filling defect (Fig. 10) within
the gastric lumen.35 If intra-abdominal abscess is suspected, oral and
Imaging of Complications After Bariatric Surgery
239
Figure 10.
Intragastric erosion two years after band insertion. Water soluble contrast
swallow shows a thin sliver of contrast outlining the outside edge of the band (arrow),
signifying band erosion inside the stomach. Reprinted with permission of Dr. Shuvro
H. Roy-Choudhury and Elsevier.8

intravenous contrast enhanced CT can show abnormal perigastric fluid
collections and extraluminal gas that is useful in making this diagnosis.30
Band slippage
This band is held in position by its circular wrapping effect, positioning
above the lesser omentum (using a pars flaccida technique), and suture
fixation of the anterior band in an anterior gastric seromuscular tunnel.
Band slippage has been associated with a number of factors including
the surgical technique used, type of band employed and history of
intractable vomiting. The band can slip anteriorly or posteriorly, of
which the latter is more common due to anchoring of the band anteriorly
to the stomach using sutures. Anterior or posterior slip can result in
associated gastric herniation and eccentric pouch dilatation as part of the
band slip–hernia–pouch dilatation complex (Fig. 7).
Patients with slipped band present with food intolerance, vomiting
and rapid weight loss (see above). Posterior slippage used to happen very
commonly with the older technique of transbursal band placement.
However, the incidence of posterior slippage has reduced markedly from
30 per cent to less than 1–6 per cent since the use of the pars flaccida tech-
nique.10,11 Band slip is also reduced with the use of newer larger sized
bands,36 although it still has a reported incidence of 0.3 per cent.37 If
severe, it can result in gastric volvulus and/or gastric obstruction.
Anterior slippage is usually due to disruption of the anterior seromus-
cular tunnel sutures, or the gathering of too much of the anterior fundus to
form the pouch. If the fundus is redundant and emptying poorly, it will
continue to enlarge and present as an enlarged pouch superior and lateral
to the band. A high seromuscular suture to the diaphragmatic crus can
reduce this incidence to 0.01 per cent (Mr Paul Super, consultant surgeon,
Heart of England NHS Trust, pers. comm.).
During UGI assessment of patients with band slip, the control film
shows abnormal angulation of the gastric band lying in a more horizontal
plane than usual, suspicious for slippage. The anterior or posterior nature
of the slippage can easily be diagnosed on lateral or oblique swallows. In
a few patients, the band slippage can be intermittent in nature resulting in
symptomatology only when the obstruction is present. In these patients,
the examination may be normal when the band has fallen back to its native
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J. C. Varghese and S. H. Roy-Choudhury

position. It may take several UGI examinations before the correct diagno-
sis is made.5 The easiest way to make the diagnosis is to perform the UGI
when the patient is acutely symptomatic.
Balloon complications
Balloon deflation
True balloon leakage occurs with an incidence of 4 per cent. Its cause is
usually iatrogenic (inappropriate surgical handling with inadvertent punc-
ture) if presenting early, and degenerative (tears in the balloon or breaks
at the edge of the inner side of the balloon from fatigue) if presenting late.
This leads to eventual patient weight gain due to increase in stomal size.38
This complication can be diagnosed clinically by rapid loss of effect of
inflation or radiologically by port injection of radiopaque contrast
material, which should leak out from the band (Fig. 11). Port injection
Imaging of Complications After Bariatric Surgery
241
Figure 11.
Band leakage in a patient with repeated loss of effect following band adjustments.
Injection of water-soluble contrast material through the port confirms leakage from the band
(arrows). Reprinted with permission of Dr. Shuvro H. Roy-Choudhury and Elsevier.8

using Tc99-colloid and scintigraphy detection of leak has also been
described as a more accurate way to diagnose this complication.38
A more indolent cause for loss of balloon integrity has also been pos-
tulated. The balloon acts as a semi-permeable membrane and can slowly
leak out normal saline over a prolonged period of time, resulting in bal-
loon deflation and loss of restriction.39 Use of contrast material diluted
with water to make it iso-osmolar to plasma (150 mg/ml) for balloon
inflation better maintains volume and leads to fewer such complications.39
It is important to note that the use of hyperosmolar contrast material can
have the opposite effect with absorption of water and over-inflation of the
balloon.
Eccentric balloon herniation
Focal weakness with herniation of the balloon is a rare complication that
occurred more frequently with the older bands. A localized weakness in
the balloon can lead to focal eccentric herniation that is only seen in cer-
tain imaging projections.5,8 Thus, if the stoma is not visualized with the
herniation in profile, the size of the stoma can be overestimated during
band inflation. This can lead to over-tightening of the stoma and eventu-
ally concentric pouch dilatation. Thus, it is vitally important to inject the
balloon with water-soluble contrast material and view it in all projections
to identify any focal eccentric band herniation in patients presenting with
acute concentric pouch dilatation.5,8
Connecting tube and port complications
These are common and seen in 7–14 per cent of patients. In a series of
1,272 port related complications were seen in 91 patients who required
103 revisional procedures. These included 62 system leaks, 19 infections
and 12 others.40 Routine use of radiology and sterile techniques are the
keys to reducing these complications.
Connecting tube complications
Connecting tube complications would include kinking (Fig. 12), twisting
and detachment (Fig. 13) from its connection to the band or port. The
latter is more common with Swedish bands and can be reduced by
scrunching the connecting tube to the port attachment at the time of
242
J. C. Varghese and S. H. Roy-Choudhury

Imaging of Complications After Bariatric Surgery
243
Figure 12.
Connecting tube kink. Scout film form a fluoroscopic study shows kink in the
connecting tube (arrow) acting as a one-way valve, making aspiration more difficult than
injection.
Figure 13.
Disconnection of connecting tube from the port. Injection of water-soluble
contrast medium through the port immediately results in leakage of contrast material
around the port (arrow) indicative of disconnection of connecting tube at the port site.

insertion. Having a shorter loop of tube in the subcutaneous tissue can
reduce tube kinkage (Mr Paul Super, pers. comm.). Similar to diagnosis of
balloon integrity, a radiographic method involving water-soluble contrast
material injection into the port under fluoroscopy, or a nuclear isotope
injection (Technetium or Thallium) with gamma camera detection can be
used for diagnosis of kinks and leaks.
Port complications
Port complications include port inversion and infection. Despite being
attached to the anterior rectus sheath using sutures, the port can tilt,
migrate or invert due to patient manipulation or spontaneous disloca-
tion. The commonest port-related problem is tilting, which makes
clinical and radiological access for puncture difficult. The use of C-arm
fluoroscopy or ultrasound guidance may be required for successful
access. Occasionally, the port is totally inverted such that it requires sur-
gical revision. This problem can be reduced if the port is fixed at all four
corners at the time of surgery close to the xiphisternum (Mr Paul Super,
pers. comm.).
Port infection can be due to localized infection from dermal
flora,15,41,42 or deep-seated infection arising from band erosion.30 In fact,
port infection may be the first sign of band erosion and requires inves-
tigation to exclude this possibility. In deep-seated infections, surgical
removal of the band and intravenous antibiotic therapy is needed for
treatment. If in doubt, port infection can be diagnosed using radionu-
clide techniques such as Technetium- or Indium-labelled white blood
cell studies.
Miscellaneous
Other rare complications reported include paragastric Richter’s hernia,43
small bowel obstruction resulting from the connecting tube,44 and chronic
unremitting cough cured by band deflation.45
In summary, in spite of the complications outlined, LAGB is a
remarkably safe and well-tolerated procedure that is minimally invasive,
totally reversible and adjustable to the patient’s needs. Long term
(>10 years) complication and failure rates are yet to be fully evaluated
244
J. C. Varghese and S. H. Roy-Choudhury

though. Overall mortality is very low (3/5,827 cases) with excess weight
loss of 50–65 per cent, which can be maintained over time.46 However,
morbidity from complications does occur and can be related to the stom-
ach, the prosthesis or surgery in general. They can occur in the early or
late post-operative period. UGI series is invaluable in diagnosing these
and a radiologist conversant with the expected findings should be an inte-
gral member of the multidisciplinary team. The routine use of UGI is not
always necessary but recommended for port access and stomal size
adjustment as it provides a more objective assessment of the anatomy. CT
is complementary in the diagnosis of complications.
Roux-en-Y Gastric Bypass (RYGB)
The Roux-en-Y gastric bypass (RYGB) is a ‘mixed-type’ of surgery that
uses a combination of restriction (gastric partitioning) and malabsorption
(proximal small bowel bypass) to effect weight loss.47 It is the most com-
monly performed bariatric surgery in the United States and is performed
using the laparoscopic technique in the majority of cases.48
The technique involves dividing the stomach into two completely sep-
arate compartments by placement of a staple line across the cardia. This
creates a small proximal compartment called the ‘pouch’ in continuity
with the oesophagus, which should measure between 15 and 30 ml in
volume for effective restriction. The remaining distal stomach consisting
of the fundus, body and antrum is called the ‘remnant’ and is excluded
from the food stream by the staple line partition.
Drainage from the newly created gastric pouch is facilitated through
the creation of a ‘gastrojejunal’ anastomosis. To do this, the proximal
jejunum is divided approximately 30–50 cm from the Ligament of Treitz
to form two separate small bowel limbs. The proximal limb that is in con-
tinuity with the duodenum is called the ‘biliopancreatic limb’, and the
distal limb that is in continuity with the remainder of the distal small
bowel is called the ‘Roux-en-Y’ limb (or Roux limb for short). The cut
end of the Roux limb is over sawn and brought up in front of the trans-
verse colon (ante colic) and stomach (ante gastric), to be anastomosed in
an end-to-side fashion with the gastric pouch to form the gastrojejunal
anastomosis. Ideally, this opening should measure around 10–12 mm in
Imaging of Complications After Bariatric Surgery
245

diameter so as to provide adequate resistance to emptying without caus-
ing obstruction. The oversawn end of the Roux limb forms a short blind
ending ‘stump’ at the gastrojejunostomy that should not be confused with
a diverticulum or ulcer.48
The biliopancreatic limb free end is oversawn and anastomosed side-
to-side with the Roux limb — approximately 75–150 cm downstream
from the gastrojejunal anastomosis — to form the ‘jejunojejunal’ or
‘Roux-en-Y’ anastomosis. Downstream from this anastomosis, food com-
ing from the Roux limb mixes with bile and pancreatic juices draining
from the biliopancreatic limb as it passes distally through the remainder
of the small bowel. In summary, this surgery creates two gastric compart-
ments (pouch and remnant), two small bowel limbs (biliopancreatic and
Roux), and two anastomosis (gastrojejunal and jejunojejunal) that work in
concert to restrict and divert food to bring about weight loss. A schematic
diagram of Roux-en-Y reconstruction is shown in Fig. 14.
As with any major surgery, there are complications associated with
this procedure.50 Complications occur in 3–20 per cent of morbidly obese
246
J. C. Varghese and S. H. Roy-Choudhury
Figure 14.
Diagram showing normal Roux-en-Y surgical anatomy. Reprinted, with
permission, from Farraye F.A. and Forse R.A. (eds).49

patients after RYGB. A recent study51 of 38,501 patients undergoing
RYGB over a period of 19 years found a 30-day operative mortality of
0.24 per cent (93/38,501). The commonest causes of death were pul-
monary embolism in 32 per cent (30/93), gastrointestinal leaks in 15 per
cent (14/93) and bowel obstruction in 9 per cent (8/93). The enteric com-
plications after RYGB can be divided into early (<30 days) and late (>30
days) postoperative complications. The most commonly encountered
early complications are leaks, anastomotic obstruction and bleed. The
most commonly encountered late complications are marginal ulceration,
staple line failure (also known as gastrogastric fistula) and bowel
obstruction.
The use of radiological investigations is crucial in the early and accu-
rate diagnosis of complications after bariatric surgery.47 In general, UGI
and CT are the two most commonly used radiological tests in this regard.
A UGI performed during the first or second postoperative day, before
commencing oral intake, has been found to be very useful in the detection
of early complications such as leaks and obstruction.7,52,53 It is also partic-
ularly useful in the diagnosis of delayed complications such as staple line
failure and gastrojejunostomy stricture. A normal UGI after RYGB is
shown in Fig. 15.
CT gives a more comprehensive evaluation of the extraluminal
pathology within the abdominal cavity. It is able to detect free intraperi-
toneal gas, intra-abdominal fluid collections, mesenteric inflammatory
changes and bowel dilatation. Therefore, it is particularly useful in the
diagnosis of leaks, abscess and small bowel obstruction.7 A normal CT
after RYGB is shown in Fig. 16.
Early postoperative complications
Anastomotic leak
Gastric leak is the most serious enteric complication associated with
RYGB surgery with an incidence of 1–6 per cent52,54–62 (Fig. 17). If not
recognized and treated early, it can be a potentially lethal with a reported
mortality of 6 per cent resulting from peritonitis and ensuing sep-
sis.47,60,61 Therefore, early detection of postoperative leak is critical for
minimizing morbidity and preventing mortality.59,63,64
Imaging of Complications After Bariatric Surgery
247

248
J. C. Varghese and S. H. Roy-Choudhury
Figure 15.
Normal post-operative anatomy on upper gastrointestinal series. A single
contrast barium upper gastrointestinal series shows the gastric pouch, side-to-side gastro-
jejunostomy anastomosis (white arrow), blind ending Roux loop stump (black arrow), and
the Roux limb. P = Pouch; R = Roux limb. Reprinted, with permission, from Farraye F.A.
and Forse R.A. (eds).49
(a)
(b)
Figure 16.
Normal post-operative anatomy on CT. An intravenous contrast enhanced
axial CT without oral contrast at the level of the proximal anastomosis (a) shows the pouch
(arrow head), fluid filled remnant and the dividing staple line (arrow). The same study
through the lower anastomosis (b) shows the staples of the jejunojejunostomy (arrows),
just anterior to the left mid kidney. R = Remnant.

Leaks almost always occur in the early postoperative period
(<30 days) and arise from the site of the gastrojejunal anastomosis in the
vast majority of cases.7 However, leaks can also arise less frequently from
the gastric pouch, distal oesophagus, jejunal stump, staple line, bypassed
gastric remnant and the jejunojejunal anastomosis. Leaks at the gastroje-
junal anastomosis result from ischemic necrosis and focal perforation;
excessive tension caused by drag from the Roux-en-Y limb, suboptimal
surgical technique and dilatation of the Roux limb from distal obstruction
are all presumed causative factors. Associated staple line dehiscence with
gastrogastric fistula has been found in 31 per cent of patients with a leak.61
Most leaks extend to the left subphrenic and perisplenic areas.7,61 This
can cause hiccups, referred shoulder pain and left pleural effusion with
associated passive lung atelectasis. Associated enteric findings would include
ileus and/or small bowel obstruction (at the jejunojejunal anastomosis or
Imaging of Complications After Bariatric Surgery
249
Figure 17.
Anastomotic leak in the early post-operative period. Gastrografin upper gas-
trointestinal series in the immediate postoperative period showing a small localized leak
(white arrow) arising from the gastrojejunostomy anastomosis. Note the site of the gastro-
jejunostomy anastomosis (black arrow). P = Pouch, R = Roux limb. Reprinted, with
permission, from Farraye F.A. and Forse R.A. (eds).49

gastrojejunal anastomosis).61 There is an increased incidence of wound
infection, chronic enterocutaneous fistula, deep venous thrombosis,
pulmonary embolism and gastrointestinal bleed in patients with a leak.
Patients with leak often present with tachycardia, hypotension and
acute respiratory distress (tachypnea, hypoxia), signs which raise con-
cerns of pulmonary embolism. During the early stages of a leak, fever and
peritonitis may be absent, leading to false reassurance for a primary
abdominal abnormality.7 Chest radiograph may show a left pleural effu-
sion (due to sympathetic effusion from left subphrenic collection) that
may further raise concern for pulmonary embolism. However, the rapid
onset of increasing abdominal pain and leucocytosis should alert the
clinician to the true diagnosis of an intra-abdominal leak.61
Clinical examination is often difficult and insensitive in the diagnosis
of a leak due to the nonspecific signs (as mentioned above) and patient
size. However, radiological evaluation has been shown to be of value in
the early detection of leak.7,55,63 Specifically, the routine use of UGI in the
first or second post-operative day — before commencing oral intake —
has been advocated for detection of leaks.55,58,63,65,66 The finding of oral
contrast extravasation that communicates with a peritoneal collection or
surgical drain is diagnostic.50 The use of this type of planned early UGI
has been suggested to reduce morbidity.65
When performing UGI, a meticulous technique should be used to
diagnose even the smallest leak. A control (scout) film should always be
taken before contrast administration to distinguish small leaks from over-
lying artefacts. If a nasogastric tube is present, this should be pulled back
into the gastric pouch to prevent obturation of any small potential leak
sites.53
A single contrast study without oral gas administration is sufficient
for diagnosis. The patient is placed in a supine position on the fluoroscopy
table. While performing fluoroscopy, small volumes (20–30 ml) of water-
soluble contrast medium are given orally or instilled down the nasogastric
tube until there is adequate filling of the pouch. Observation is made for
any evidence for oesophageal hold-up, hiatal hernia, reflux or leak, as
these will modify the course of the examination.
After filling of the pouch, the patient should be rotated as much as
possible to extreme lateral positions to maximize the detection of leak.
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J. C. Varghese and S. H. Roy-Choudhury

Turning the patient into a prone position is often not possible due to
patient size, postoperative discomfort and restriction from attached
lines/tubes. Continuous vigilance with intermittent fluoroscopic examina-
tion for contrast opacification of the left subdiaphragmatic space,
perigastric region, abdominal peritoneal spaces and any surgical drains
present should be performed to detect subtle leaks (Fig. 18).
If the initial water-soluble contrast examination is normal, it is pru-
dent to repeat the examination using dilute barium to better detect subtle
leaks. The examination is not completed until delayed imaging with over-
head radiographs is obtained of the contrast reaching the distal small
bowel to exclude possible obstruction and/or leak at the jejunojejunostomy
anastomosis.
If CT is performed to detect anastomotic leak, the use of oral and intra-
venous contrast material is highly beneficial. CT has the added advantage
that an initial CT pulmonary angiogram can be performed to exclude a
potential pulmonary embolus before scanning through the abdomen. In
patients with a leak, CT can show mesenteric stranding (indicative of
Imaging of Complications After Bariatric Surgery
251
(a)
(b)
Figure 18.
Early post-operative leak shown only by opacification of a surgical drain
in situ. (a) The scout film taken before a Gastrografin upper gastrointestinal study shows
the opaque portion of a Jackson–Pratt surgical drain in position (arrow). (b) After admin-
istration of Gastrografin, there is filling of the gastric pouch (white arrow) with subsequent
contrast opacification of the length of the surgical drain (black arrows), indicative of a leak
arising from the region of the gastrojejunostomy. A small amount of contrast is seen drain-
ing into the Roux loop situated at the left upper quadrant of the abdomen. Reprinted, with
permission, from Farraye F.A. and Forse R.A. (eds).49

peritonitis), free intraperitoneal gas, and abnormal fluid collections that
may also contain oral contrast.6,67 However, the finding of free intraperi-
toneal gas per se should be interpreted with caution, as this can be a normal
finding after recent operation.61 Also, caution is required so that a distended
but otherwise normal gastric fundus containing air/fluid levels — and pos-
sible oral contrast material — is not confused with a leak. Remember also
that contrast can enter the gastric remnant by retrograde reflux through the
jejunojejunal anastomosis. Careful confirmation of the fundus being in
continuity with the gastric antrum will help to distinguish this normal
variation from a pathological leak with collection.67
Whether to perform a CT or UGI as the initial study in the diagnosis
of a leak depends on many factors including the patient condition, local
expertise/experience and expediency. CT or UGI may individually be suf-
ficient to make the diagnosis in many instances. However, when one test
is negative or equivocal, performance of the other test is recommended as
they can be complementary and increase the diagnostic yield. However,
it must be emphasized that a negative CT, UGI, or both, does not neces-
sarily exclude a life-threatening leak. Leaks from the jejunojejunal
anastomosis are especially difficult to diagnose radiologically.68
Therefore, a patient with high clinical suspicion for bowel leak should be
assumed to have a leak until proven otherwise at surgery; waiting and
watching can lead to sepsis, rapid multiorgan failure and death in these
high-risk patients.68,69 Percutaneous catheter drainage of gastric leak is
only indicated in clinically stable patients with organized well-defined
fluid collections that are easily and safely reached using a catheter. All
others should undergo emergent laparotomy for diagnosis and treatment.
Anastomotic obstruction
Gastrojejunal anastomotic obstruction occurs in the early postoperative
period with an incidence of 1.4 per cent.52 This may be due to oedema,
intraluminal lesion, fibrotic stenosis, or suboptimal surgical technique.
There is an increased incidence of this complication in patients operated
on by inexperienced surgeons during their early learning curve.70–72
Patients present with epigastric pain, inability to swallow saliva, and dry
retching; the diagnosis is usually clear at UGI or upper endoscopy.69
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It is not unusual to find mild delay in pouch emptying in patients
undergoing routine UGI studies after RYGB.52,53 However, most of these
patients have temporary hold-up at the gastrojejunal anastomosis due to
post-operative oedema (Fig. 19). The challenge is to identify the small
number of patients who have irreversible obstruction (fibrosis, iatro-
genic closure) that would require surgical revision. Manoeuvres such as
examining the patient in an erect position and using delayed films will
help with this distinction. Even the slightest drainage of contrast from
the pouch at any stage is a good prognostic sign and should warrant con-
tinued conservative management. With gradual resolution of oedema,
there should be establishment of rapid pouch emptying with sympto-
matic relief and a good clinical outcome. However, if there is persistent
hold-up of barium at the gastrojejunostomy, a nasogastric tube should
be placed under fluoroscopy for decompression and the examination
repeated a day or two later. In patients with non-oedematous obstruc-
tion, there is complete and persistent pouch obstruction. After
endoscopic confirmation, these patients should be taken back to the
operating room for take down and refashioning of the obstructed
gastrojejunostomy.
Gastrojejunostomy obstruction in the early postoperative period due
to intraluminal clot is a rare but well described finding (Fig. 20).52 It is not
unusual to find small clots in the stomach and jejunum of patients after
bariatric surgery.52 However, in the vast majority of patients these clots are
too small to cause obstruction and resolve spontaneously. However, if
they do result in obstruction, treatment with endoscopic removal or
nasogastric tube lavage can be effective.
Obstruction at the jejunojejunal anastomosis is a rare complication
and is more common after laparoscopic compared to open RYGB sur-
gery.73 In at least one study,74 it was found to be the commonest cause of
early small bowel obstruction. It occurs due to anastomotic oedema or
iatrogenic occlusion of the jejunojejunal anastomosis.69 Depending on the
extent of involvement, it can lead to obstruction of the Roux limb, the
biliopancreatic limb or both. Obstruction of the biliopancreatic limb is
equivalent to a closed-loop obstruction that can lead to dilatation of the
duodenum and gastric remnant with retained biliary and pancreatic secre-
tions.75 Developing tension can lead to staple line dehiscence and/or
Imaging of Complications After Bariatric Surgery
253

254
J. C. Varghese and S. H. Roy-Choudhury
(a)
(b)
(c)
Figure 19.
Temporary hold-up of contrast at the gastrojejunostomy due to oedema.
Gastrografin upper gastrointestinal series shows: (a) opacification of the oesophagus and
gastric pouch, with complete obstruction to flow of contrast at the gastrojejunostomy anas-
tomosis (arrow); (b) even with placing the patient in a semi-erect position, there is no flow
of contrast past the proximal anastomosis; (c) however, a supine film half an hour later
shows normal drainage of contrast into the Roux limb suggestive of anastomotic oedema.
E = Oesophagus, P = Pouch.

gastrojejunostomy leak.53 Because of its closed loop nature, this complication
can be difficult to diagnose using UGI or upper endoscopy. CT is the
modality of choice for investigation of patients with abdominal bloating
and hiccups, suspicious for this diagnosis.53,74
Haemorrhage
Haemorrhage is a relatively uncommon complication after RYBG with an
incidence of 0.5–5 per cent. However, many of these patients are on
prophylactic anti-thrombotic medication for prevention of venous throm-
boembolic disease or co-morbid cardiac conditions that can aggravate
these bleeding complications.76
Imaging of Complications After Bariatric Surgery
255
(a)
(b)
Figure 20.
Gastrojejunostomy obstruction due to clot in the early post-operative period.
Gastrografin upper gastrointestinal series showing: (a) large clot (arrows) within the
gastric pouch causing complete obstruction to drainage of contrast from the stomach;
(b) a repeat study 24 hours after saline lavage through a nasogastric tube shows resolution
of clot with normal contrast opacification of the Roux limb (white arrow). Note the opaque
portion of a Jackson–Pratt drain close to the gastrojejunostomy site (black arrow).
P = Pouch.

Haemorrhage in the early postoperative period can originate from
many sites including fresh staple lines (gastric partition, gastrojejunos-
tomy anastomosis, jejunojejunostomy), cut edges of the mesentery,
damaged blood vessels (short gastrics), damaged spleen or trocar site
injury. The site of bleeding can be intraluminal, mural or intraperitoneal,
depending on the cause. Patients can present with haematemesis, shock or
gastrointestinal obstruction. Larger clots may give rise to temporary
bowel obstruction (Fig. 20). More often than not, bleeding is subclinical
and self-limiting. Most of the time these patients can be managed with
blood transfusion and supportive care. Bleeding in the late postoperative
period occurs most often due to marginal ulceration77 and is described in
more detail below.
The best test for the investigation of bleeding is the upper GI
endoscopy as it can visualize the bleeding site and treat the cause. If
endoscopy is normal, occult intra-abdominal haemorrhage should be sus-
pected and a CT of the abdomen performed. CT will show free fluid or,
more probably, a localized haematoma of varying appearance and density,
depending on age. Occasionally, associated gastric wall thickening will
also be found due to a mural haematoma. UGI is relatively insensitive in
the diagnosis of marginal ulcers unless they are large and deep.
Occasionally, selective mesenteric angiography may be required for
diagnosis and treatment of intractable bleeding.
Bleeding arising from the bypassed stomach and duodenum should be
considered when no other site is identified at endoscopy or standard radi-
ological imaging. As the bypassed biliopancreatic limb is a relatively
‘blind’ area that is not readily accessible to a scope or contrast from an
UGI study, this poses a difficult and interesting challenge for imaging. In
such patients, confirmation of bleeding from the biliopancreatic limb can
be attempted using Tc-red cell labelled radionuclide studies.
Late postoperative complications
Marginal ulcer
This is a complication of the late postoperative period with an incidence
of around 0.5–15 per cent.6,47,78 Classically, marginal ulcers are shallow
256
J. C. Varghese and S. H. Roy-Choudhury

ulcers occurring at the jejunal side of the gastrojejunal anastomosis
(Fig. 21). However, these can occur anywhere around the gastrojejunos-
tomy margin and some can be very large. They can lead to complications
with haemorrhage77 and perforation.79,80
The aetiology of marginal ulcer remains unclear but has been postu-
lated to be due to use of non-steroidal anti-inflammatory drugs, ischemia
at the anastomotic site and infection with Helicobacter pylori. There is
also an increased incidence of marginal ulcers with staple line failure, pre-
sumably due to exposure of this site to gastric acid from reflux through
the gastrogastric fistula (Fig. 22).
Presentation of marginal ulcers includes severe dyspepsia, epigastric
pain, vomiting and/or bleeding. As mentioned above, radiological investi-
gations are relatively insensitive in their diagnosis as the ulcers are often
small and shallow.81 Larger ulcers can be diagnosed as elsewhere in the gas-
trointestinal system by the findings of an excavated mucosal defect
associated with persistent barium pooling and radiating folds. Upper
endoscopy is by far the most useful test for the diagnosis of marginal ulcers.
Imaging of Complications After Bariatric Surgery
257
(a)
(b)
Figure 21.
Marginal ulcer. Single contrast barium upper gastrointestinal series shows:
(a) contrast filling of a large ulcer crater (arrows) situated at the jejunal side of
the gastrojejunostomy; (b) persistent pooling of contrast (arrow) on delayed images
indicative of an acute ulcer. P = Pouch, R = Roux limb. Reprinted, with permission, from
Farraye F.A. and Forse R.A. (eds).49

Apart from marginal ulcers, peptic ulcers can also occur anywhere in
the gastrointestinal tract, as in non-bariatric patients. Duodenal ulcera-
tion occurring in the biliopancreatic limb can be extremely difficult to
diagnose and treat,82 as discussed above.
Staple line dehiscence
Staple line dehiscence (or gastrogastric fistula) occurs when there is par-
tial or complete breakdown of the partition between the gastric pouch and
remnant, due to a tear or the staples coming away (Fig. 23). This usually
occurs during the early postoperative period with an incidence of around
20 per cent. The aetiology is thought to be due to excessive strain being
placed on the staple line from eating large volumes of poorly digested
food with resultant chronic gastric pouch distention.66 This breakdown of
258
J. C. Varghese and S. H. Roy-Choudhury
Figure 22.
Giant marginal ulcer associated with gastrogastric fistula. Single contrast
barium upper gastrointestinal series showing barium from gastric pouch (black arrow)
communicating with gastric fundus (long white arrow), and coating an air filled antrum
(white arrow heads) due to staple line dehiscence. There is drainage of barium from the
pouch to the Roux limb (short white arrow) despite the presence of a giant ulcer (black
arrow heads) arising from the gastrojejunostomy site. Reprinted, with permission, from
Farraye F.A. and Forse R.A. (eds).49

the staple line results in loss of the restrictive and bypass effects of the sur-
gery leading to stabilization or regaining of weight, prompting further
investigations.
UGI is by far the best test for diagnosis of gastrogastric fistula.53
Endoscopy will show large defects, but UGI will reveal even the smallest
gastrogastric fistula. It will show extravasation of contrast from the pouch
with progressive opacification of the gastric remnant (Fig. 24). In the nor-
mal post-operative situation, there should be absolutely no contrast
material seen entering the remnant, with all contrast exiting the pouch
through the gastrojejunostomy. However, care must be taken not to con-
fuse the occasional contrast opacification of the remnant resulting from
retrograde filling through the jejunojejunostomy. In a true leak, there will
be early and progressive contrast opacification of the remnant, well before
there is contrast reaching the jejunojejunal anastomosis where reflux
could occur.
In patients with staple failure, CT can also be diagnostic if performed
with administration of oral contrast. In patients with a fistula, there is
Imaging of Complications After Bariatric Surgery
259
Figure 23.
Staple line dehiscence. Gastrografin upper gastrointestinal series in the
immediate post operative period shows contrast leak from the pouch (black arrow) filling
the gastric remnant (white arrow), indicative of a gastrogastric fistula. Reprinted, with
permission, from Farraye F.A. and Forse R.A. (eds).49

260
J. C. Varghese and S. H. Roy-Choudhury
(a)
(b)
(c)
Figure 24.
Staple line dehiscence. Gastrografin upper gastrointestinal series in the early
post operative period shows: (a) contrast leak from the gastrojejunostomy (black arrow).
Note an air/fluid level in the unopacified gastric fundus (white arrow); (b) a subsequent
film shows progressive contrast coating of the gastric body (white arrows);
(c) a delayed film shows progressive contrast filling of the gastric remnant with pooling of
contrast within the fundus and coating of the gastric antrum (black arrows). P = Pouch,
R = Roux limb, F = Fundus.

contrast opacification of the gastric body and antrum that is normally of
fluid density (Fig. 25). With the advent of helical CT, many in the radiol-
ogy community are now questioning the need for routine administration
of positive oral contrast material in patients undergoing abdominal CT.
Irrespective of the outcome of this debate, a history of RYGB should be
an indication for routine administration of positive oral contrast material
in order not to miss staple line dehiscence in both symptomatic and
asymptomatic patients.
Bowel obstruction
Small bowel obstruction is usually a late complication of bariatric surgery
with an incidence of 1–5 per cent.6,47,62,73,74,83,84 They are most commonly
caused by adhesion, stricture and internal herniation. Rare causes would
include intussusception and bezoar related obstruction.85,86
UGI and CT are the most frequently used imaging tests in patients
with suspected bowel obstruction, although CT has been shown to be
Imaging of Complications After Bariatric Surgery
261
Figure 25.
Staple line dehiscence. Oral contrast enhanced axial CT through the upper
abdomen shows contrast material in the gastric pouch (long black arrow) as would be
expected, but contrast material also in the gastric remnant (white arrow) that is abnormal
and indicative of a gastrogastric fistula. Note portions of the dividing staple line (small
black arrows). Reprinted, with permission, from Farraye F.A. and Forse R.A. (eds).49

superior to UGI in making this diagnosis.74 Not only does CT enable the
diagnosis of obstruction to be made, but it may also identify the under-
lying cause and exclude associated complications such as perforation
and/or abscess. If the CT is normal or equivocal (and there is no obvi-
ous perforation) progressing to an UGI may identify functional or
mucosal lesions that may explain patient symptomatology. Although
these tests are complementary, CT is generally recommended before a
UGI in the investigation of suspected bowel obstruction. Irrespective of
the cause, the radiological hallmark of obstruction is the same: a
change in bowel calibre (transition point) associated with proximally
dilated and distally collapsed bowel loops. As obstructions tend to be
proximal in the post-RYGB patient, characteristic findings at imaging
includes dilatation of the oesophagus, gastric pouch dilatation, wide
opening of the gastrojejunostomy and dilatation of the Roux limb
(Fig. 26). CT also helps with the identification of the actual cause of
obstruction in many patients, particularly when there are characteristic
radiological findings such as that of intussusception. However, in a few
patients, the exact cause of obstruction remains obscure until surgical
exploration.
Adhesions
This is a leading cause of small bowel obstruction, particularly in patients
undergoing RYGB using the open surgical technique.73 However, with the
advent of laparoscopic RYGB, the incidence has much decreased. The
aetiology is related to organizing inflammatory peritoneal bands leading
to extrinsic bowel compression. It can develop rapidly and usually pres-
ents in the early postoperative period with symptoms of colicky
abdominal pain and vomiting. On imaging, dilated proximal small bowel
with a sharp transition point is often identified (Fig. 27). Surgical
exploration with release of adhesion is both diagnostic and therapeutic.
Anastomotic stricture
Anastomotic structure can occur at the gastrojejunal or the jejunojejunal
anastomosis. Gastrojejunostomy stricture occurs with an incidence of
262
J. C. Varghese and S. H. Roy-Choudhury

Imaging of Complications After Bariatric Surgery
263
(a)
(b)
(c)
Figure 26.
Petersen’s hernia. Oral contrast material enhanced CT of the abdomen:
(a) scout film from the study showing hold-up of oral contrast material in the oesophagus
(black arrow), contrast filled dilated pouch, Roux limb and portion of
the closed-loop obstructed herniated small bowel; (b) a coronal CT image shows dilated
gastrojejunostomy anastomosis (black arrows) and sites of closed loop obstruction (white
arrows); (c) an axial CT image shows the ‘mushroom’ sign where the herniated bowel
together with its mesentery and blood vessels are pinched into a waist (arrows), as they
pass through the hernial defect. P = Pouch, R = Roux limb, S = Small bowel.

3–27 per cent.6,47,48,56,78,83,84 Patients usually present with nausea, vomiting,
regurgitation, dysphagia or epigastric pain87,88 during the late postopera-
tive period, with a mean of 48 days from surgery in one study.87 The cause
of the stricture is thought to be due to ischemia from tension and
compromised blood supply.78,89
UGI and upper endoscopy are both useful and shown to correlate well
with each other in the evaluation of gastrojejunal anastomotic structure.90
The most useful radiological investigation is the UGI, which may show a
number of findings including concentric dilatation of the pouch, pinhole
sized ostomy, delayed pouch emptying, open gastro-oesophageal junction
and a dilated lower oesophagus associated with reflux87 (Fig. 28). When
performing the UGI, lateral and/or steep oblique (>45°) imaging is
recommended for full visualization of the anteriorly placed gastroje-
junostomy and any strictures that may be hidden on the frontal projection
alone.7,87
264
J. C. Varghese and S. H. Roy-Choudhury
(a)
(b)
Figure 27.
Bowel obstruction due to adhesion proved at surgery. Single contrast barium
upper gastrointestinal series shows: (a) abnormal dilatation of the Roux limb, relatively
collapsed distal bowel and a transition point (black arrow); (b) a delayed film shows per-
sistently dilated contrast filled Roux limb and a relatively collapsed partially contrast filled
distal small bowel. P = Pouch, D = Dilated Roux limb, C = collapsed distal small bowel.
Reprinted, with permission, from Farraye F.A. and Forse R.A. (eds).49

Imaging of Complications After Bariatric Surgery
265
(a)
(b)
(c)
Figure 28.
Gastrojejunostomy stricture. (a) A barium swallow study shows tight ‘pin-
hole’ stricture at the gastrojejunostomy (long white arrow), a concentrically dilated barium
filled pouch (short white arrow) and barium hold-up in a dilated lower oesophagus asso-
ciated with patulous gastro-oesophageal junction (black arrow). Reprinted, with
permission, from Farraye F.A. and Forse R.A. (eds).49 An oral and intravenous contrast
material enhanced CT from another patient shows: (b) a markedly dilated fluid filled
gastric pouch on axial imaging through the upper abdomen; (c) isolated dilatation of the
gastric pouch with distally collapsed small bowel on a coronal reconstructions through the
abdomen. P = Pouch, C = Collapsed distal small bowel.
Other rare causes of gastrojejunostomy obstruction include ostomy
impaction from food or bezoar. Hiatal hernia, marginal ulceration and
small bowel obstruction are among other conditions simulating gastroje-
junostomy obstruction. When patients present with symptoms consistent

with pouch obstruction, UGI can be useful in distinguishing ostomy stric-
ture from many of these other conditions. It is the most accurate test in the
diagnosis of hiatal hernia and reflux.
Stricture at the jejunojejunal anastomosis is a less frequent but, nev-
ertheless, a serious complication after RYGB surgery (Fig. 29). The
stricture at the jejunojejunostomy can cause obstruction of the Roux-en-Y
limb alone, the biliopancreatic limb alone or both limbs simultaneously
(with or without continuity between the two limbs). In most cases, an UGI
will show a much dilated Roux-limb with obstruction at the anastomosis,
except in the rare case of an isolated biliopancreatic limb obstruction. In
the latter, the UGI may be perfectly normal with progress of barium
through the distal small bowel. Thus a life-threatening closed loop
obstruction (the biliopancreatic limb is closed off proximally by the
266
J. C. Varghese and S. H. Roy-Choudhury
Figure 29.
Jejunojejunostomy anastomosis stricture causing Roux limb obstruction.
Oral contrast material enhanced coronal CT of abdomen showing fluid filled dilated pouch
and Roux limb, with point of obstruction at the jejunojejunostomy where suture material
is seen (arrows). P = Pouch, R = Roux limb, C = Collapsed distal small bowel.

gastric partitioning and closed off distally at the jejunojejunostomy) may
be missed if UGI alone is performed. The closed off biliopancreatic limb
distends markedly due to continuous filling with bile and pancreatic juice,
leading to jaundice in severe cases. The diagnosis is solely and accurately
made by CT, which will show a cystic fluid collection in the upper
abdomen, posteromedial to the free margin of the liver.
Internal herniation
Internal herniation is the commonest cause of small bowel obstruction
after RYGB surgery with a reported incidence of 0.2–5 per cent.91–93 It is
caused by herniation of small bowel through surgically created defects in
the mesentery, resulting in a ‘closed-loop’ type of obstruction.91,94 It may
involve any portion or length of the small bowel, including variable por-
tions of the Roux or biliopancreatic limbs. Although some have suggested
increased incidence of internal hernias after laparoscopic as compared to
open RYGB,95 others have found no significant difference.73
There are three distinct types of internal hernias based on their
anatomic sites of herniation: transmesenteric, transmesocolic and Petersen
hernia. The transmesenteric herniation occurs through a defect in the
small bowel mesentery near the jejunojejunal anastomosis (Fig. 30); the
transmesocolic herniation occurs through a defect in the transverse meso-
colon created for retrocolic passage of the Roux loop88 (Figs. 31 and 32);
and the Petersen herniation occurs through a mesenteric defect behind the
Roux limb itself 91 (Fig. 26). Depending on the study, the transmesen-
teric,96 transmesocolic92,97 and Petersen98 hernias have all been reported
to occur with the most increased frequency. However the technique of
bringing the Roux limb anterior to the transverse colon, (antecolic) rather
than posteriorly through the transverse mesocolon, has considerably
reduced the incidence of transmesocolic herniation. Many surgeons try to
close any remaining mesenteric defects using nonabsorbable sutures at the
time of the initial surgery to prevent the incidence of the other types of
hernias also.
Internal hernias most commonly occur during the late postoperative
period because mesenteric hernial defects enlarge with weight loss,
making easier for herniation to take place. It is a potentially lethal
Imaging of Complications After Bariatric Surgery
267

268
J. C. Varghese and S. H. Roy-Choudhury
(a)
(b)
(c)
(d)
Figure 30.
Transmesenteric herniation proved at surgery. Oral and intravenous contrast
material enhanced axial CT shows: (a) dilated fluid-filled herniated small bowel loops at
the left upper quadrant of abdomen (arrows); (b) the ‘pinch sign’ as the hernial defect
indents on the side of the herniating bowel (arrow); (c) bunched-up blood vessels running
in a unusual vertical orientation (arrow) in the root of the small bowel mesentery as it her-
niates; (d) dilated contrast-filled bowel proximal to the level of herniation. S = Small
bowel dilated proximal to herniation.
complication with variable and nonspecific clinical presentation.92,99,100
Patients typically present with intermittent postprandial colicky abdomi-
nal pain and nausea, with or without vomiting. If strangulation occurs,
patients present with sudden onset of abdominal pain and peritonitis.
However, in the majority of patients the herniation is intermittent and
low-grade, with insidious symptoms and subtle imaging findings.96
Both UGI and CT have been used in the diagnosis of obstructed inter-
nal herniation.6,7 On UGI, there is almost always the finding of dilated

Imaging of Complications After Bariatric Surgery
269
Figure 31.
Transmesocolonic herniation proved at surgery. Oral and intravenous con-
trast material enhanced axial CT showing crowding and swirling of blood vessels through
the mesenteric defect in the transverse mesocolon (small arrow), associated with dilatation
of the herniated small bowel (large arrow).
contrast-filled oesophagus, gastric pouch and proximal Roux limb with a
dilated gastrojejunal anastomosis.6,7 In addition, the finding of fixed
dilated loops of small bowel (the herniated bowel) at the left upper to mid
abdomen is characteristic. If these fill with orally administered contrast
material, they will show stasis and slow emptying. There is rarely ade-
quate opacification of the collapsed distal small bowel. Despite these
latter limitations, an UGI can be extremely helpful in confirming and
delineating small bowel obstruction from internal herniation.
CT is the best diagnostic test for diagnosis of internal herniation.
A recent study98 looked at the usefulness of seven specific CT signs in the
prediction of internal herniation:
1)
the swirled appearance of mesenteric fat or vessels at the root of the
mesentery (swirl-sign);
2)
presence of small-bowel obstruction;
3)
clustering of small bowel loops;
4)
mushroom shape of the herniated mesenteric root with crowding and
stretching of the mesenteric vessels;
5)
tubular or round shape of distal mesenteric fat closely surrounded by
bowel loops;

270
J. C. Varghese and S. H. Roy-Choudhury
(a)
(b)
(c)
(d)
Figure 32.
Transmesocolonic herniation proved at surgery. Oral and intravenous con-
trast material enhanced axial CT of the abdomen: (a) scout film from the study shows
dilated loops of small bowel occupying the left upper quadrant of the abdomen (arrow);
(b) an axial image through the upper abdomen shows dilated gastrojejunostomy anasto-
mosis (arrows) due to obstruction; (c) engorged blood vessels (arrow) are seen in the
mesentery of the herniated small bowel; (d) there is crowding and swirling of blood ves-
sels in the root of the mesentery (arrows), at the site of herniation through the transverse
mesocolon. P = Pouch, R = Roux limb, D = Dilated obstructed herniated small bowel.
6)
small bowel other than duodenum passing posterior to the superior
mesenteric artery;
7)
right-sided location of distal jejunal anastomosis.

Of these, the ‘swirl’ sign was the most sensitive and single most useful
sign in the diagnosis of internal herniation (Fig. 32). The addition of the
‘mushroom’ sign (Fig. 26) — the appearance of the herniated bowel
mesentery and its vessels traversing the hernial defect — increased the
sensitivity of the diagnosis. All the other signs were highly specific but
poorly sensitive. Another specific but poorly sensitive indicator called the
‘pinch sign’ has also been described where the herniating bowel is
pinched by the surrounding hernial defect (Fig. 30).100
The typical CT findings of small bowel obstruction due to internal
herniation would include:
1)
proximally situated fluid/contrast filled dilated oesophagus and
pouch;
2)
clustered fluid/contrast filled dilated loops of small bowel at the left
upper to mid abdomen, corresponding to the internally herniated
bowel undergoing closed loop obstruction;
3)
distally collapsed poorly opacified small bowel loops situated
predominantly at the right lower quadrant of abdomen/pelvis.
The findings of the ‘swirl’ and ‘mushroom’ signs would increase the diag-
nostic confidence. The presence of mesenteric congestion (increased fat
attenuation) and peritoneal fluid will be determined by the grade and
chronicity of obstruction. The finding of bowel wall pneumatosis and free
intraperitoneal gas would be suggestive of bowel necrosis and perforation,
respectively.
Specific CT features have been described to help with diagnosis of par-
ticular types of internal hernias. In cases of transmesocolic herniation,
herniated small bowel is located posterior to the stomach and may exert a
masseffect on its posterior wall.7,94 In addition, the findings of a high riding
jejunojejunal anastomosis may also point to this diagnosis.100 With the
transmesenteric hernia, clustered bowel is found pressedagainst the anterior
abdominal wall with no overlying omental fat, causing centraldisplacement
of the colon. The Petersen hernia is difficult to diagnose because it has
neither a confining sac nor a characteristic location, and its presence may
be obvious only from the finding of engorgement and crowding of the
mesenteric vesselsand presence of small-bowel obstruction.7,94
Imaging of Complications After Bariatric Surgery
271

Despite the above pointers, in actual practice it is difficult to distin-
guish between these various hernias with certainty, as the various hernial
defects are very close to each other with little distinguishing features
between them. Happily, excruciating efforts to make such fine distinction
are not necessary, as it does not change clinical management. Once inter-
nal herniation is diagnosed, an experienced bariatric surgeon has to
perform an exploratory laparotomy, ‘run’ the bowel, find which defect is
causing the herniation, reduce the hernia and close the offending defect,
as well as any other defects present.
When interpreting a CT in a RYGB patient with symptoms of small
bowel obstruction, the primary concern of the radiologist is to determine
whether a mechanical obstruction is present or not, and to diagnose any
associated complications such as ischemia or perforation. Then, using the
above-described imaging signs, the radiologist should be able to make a
diagnosis of internal herniation with some degree of confidence. For the
radiologist to obsess as to which of the three types of internal hernias is
present is academically interesting but clinically unnecessary. In any cen-
tre where there is close cooperation between the surgeon and the
radiologist, the surgeon should be able to reveal the exact diagnosis soon
after surgery!
Intussusception
Intussusception after RYGB is an extremely rare complication and occurs
almost exclusively at the jejunojejunal anastomosis.101–105 It can be ante-
grade (isoperistaltic) or retrograde (antiperistaltic) in nature.105 The
aetiology remains unclear but is probably multifactorial involving a lead
point (suture lines, adhesions, lymphoid hyperplasia)103 motility distur-
bances,101 and aberrant intestinal pacemakers.106 It presents in the late
postoperative period and so far has been only seen after open RYGB
surgery.105
Patients can present with a range of symptomatology including nau-
sea, retching vomiting, epigastric pain, intermittent diffuse abdominal
pain, diarrhoea, and haematemesis. However, symptoms can be vague,
physical examination nonspecific and patient condition stable with no
toxicity.105 Therefore, a high index of suspicion has to be maintained for
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early radiological evaluation and surgical intervention before severe
complications of bowel necrosis and perforation occur.
CT is the first line imaging for the suspected diagnosis of intussus-
ception.106 It will show the characteristic target sign on transverse, and
sausage-like appearance on the longitudinal sections taken along the cen-
treline of the bowel. The finding of fat in the mesentery of the
intussusceptum being dragged into the lumen of the intussuscipiens is
diagnostic (Fig. 33). There is usually a fluid-filled dilation of the proximal
Roux limb and pouch.
Bariatric surgery patients with intussusception invariably require
reoperation to prevent life threatening complications. Therefore, the sus-
picion of intussusception on clinical or imaging grounds requires
immediate consultation by an experienced bariatric surgeon. At
exploratory laparotomy, the intussusception can be difficult to reduce and
bowel infarction likely. The safest option might be en-bloc resection of the
intussusception with reconstruction of the entire jejunojejunostomy.
Miscellaneous
Other complications after RYGB include incisional hernia, intra-abdomi-
nal abscesses unrelated to leak and liver/splenic infarctions.53,62,67 The
incidence of incisional hernia has decreased with the change from open to
laparoscopic surgery, although this has brought its own complications
with port-site hernias.47 Intra-abdominal fluid collections and abscesses
can occur unrelated to leaks in about 2 per cent of patients after RYGB.6,69
Any suspicion of intra-abdominal sepsis should be investigated early
using CT, as left undiagnosed can lead to multiorgan failure and death.69
Summary
Imaging is used in bariatric patients to evaluate the technical success of
surgery, document baseline anatomy, and diagnose postoperative compli-
cations. The UGI series and CT are the most commonly used
investigations for this purpose. Together they provide functional, dynamic
and cross-sectional information that is sufficient to identify most post-
operative complications. There should be a low threshold for performing
Imaging of Complications After Bariatric Surgery
273

274
J. C. Varghese and S. H. Roy-Choudhury
(a)
(b)
(c)
Figure 33.
Retrograde intussusception at the Roux-en-Y anastomosis proved at surgery.
Oral and intravenous contrast material enhanced CT abdomen: (a) axial CT through lower
abdomen shows retrograde migration of distal jejunum (short black arrow) together with
its mesentery (long black arrow) intussuscepting through the anastomosis (short white
arrow) into the pancreaticobiliary limb (long white arrow); (b) coronal CT reconstruction
shows the intussusceptum (arrow heads) and its mesenteric fat (arrow) more clearly.
(c) Photograph of the en-bloc resection of the anastomosis shows the infarcted intussus-
cepted small bowel. R = Roux limb dilatation due to obstruction. Reprinted, with
permission, from Farraye F.A. and Forse R.A. (eds).49

imaging in symptomatic patients, as early diagnosis can lead to lifesaving
therapy.
Compared to the average subject, bariatric patients pose a greater
diagnostic challenge to the radiologist due to their larger size. Therefore,
robust imaging equipment53 meticulous radiological technique and con-
siderable interpreter expertise is required for diagnosis. Most importantly,
any imaging finding should be interpreted in the light of the patient’s clin-
ical, laboratory and endoscopic findings in order to arrive at the most
accurate diagnosis and the best management plan for the individual
patient.
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