DOI:10.2214/AJR.05.1087
AJR 2006; 187:1288-1295
© American Roentgen Ray Society
Bowel Complications Seen on CT After Pancreas Transplantation with Enteric Drainage
Chandana G. Lall1,
Kumaresan Sandrasegaran1,
Dean T. Maglinte1 and
Jonathan A. Fridell2
1 Department of Radiology, UH 0279, Indiana University School of Medicine, 550 N
University Blvd., Indianapolis, IN 46202.
2 Department of Surgery, Indiana University School of Medicine, Indianapolis,
IN.
Received June 24, 2005;
accepted after revision August 8, 2005.
Address correspondence to K. Sandrasegaran
(ksandras{at}iupui.edu).
Abstract
OBJECTIVE. Bowel-related complications from pancreas transplantation
account for much of the postsurgical morbidity. In a review of 98 pancreas
transplant recipients, we found 19 (19.4%) with such complications.
CONCLUSION. The most common problems were small-bowel obstruction
and anastomotic leaks. Adhesions and internal hernias accounted for most
postoperative bowel obstructions.
Keywords: CT • diabetes mellitus • enteric drainage • gastrointestinal imaging • pancreas transplantation • small bowel
Introduction
Pancreatic transplantation offers the potential for normalization of blood
sugar levels in patients with diabetes mellitus. The procedure helps to
stabilize or reverse many of the complications associated with diabetes, such
as neuropathy [1], and improves
quality of life. With refinement of surgical and immunosuppressant techniques,
graft survival is as high as 95% at 1 year
[2]. A major barrier to the
success of pancreas transplantation is the high rate, approximately 30%, of
surgical complications, often requiring a second operation
[3,
4]. Prior reports have focused
on vascular complications, rejection, and pancreatitis
[5-7].
In this pictorial essay we describe the bowel complications occurring with
enteric drainage of exocrine secretions as a result of pancreas
transplantation.
Technique of Pancreas Transplantation with Enteric Drainage
To understand the complications, it is essential to have a good
understanding of the surgical technique. In the past, pancreas transplantation
was often performed with exocrine secretions draining into the urinary
bladder. This technique resulted in several complications such as metabolic
alkalosis and urinary calculi.
Drainage of exocrine secretions into the small intestine, or enteric
drainage, has recently become more widely used because it overcomes many of
these problems. Simultaneous renal transplantation improves survival of the
pancreas allograft. Both organs are placed intraperitoneally. Enteric exocrine
drainage is performed using a staple technique, in which the donor duodenum is
anastomosed side to side to native jejunum, 30-40 cm distal to the ligament of
Treitz [2]. The portal vein of
the pancreatic allograft is anastomosed to the recipient right external iliac
vein. The donor common iliac artery is anastomosed to the recipient right
external iliac artery (Fig. 1).
This technique is called systemic enteric pancreatic transplantation. This
report deals exclusively with patients who had this surgery.
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Fig. 1 —llustration of systemic-enteric pancreatic transplantation
procedure where exocrine secretions drain into small intestine. Donor Y graft
is anastomosed to recipient right common iliac artery. Donor portal vein is
anastomosed to recipient common iliac vein. Enteric anastomosis for exocrine
pancreatic drainage is between donor duodenum and recipient jejunum. Renal
artery and vein from donor kidney are anastomosed to recipient external iliac
artery and vein, respectively. Inset shows construction of Y graft (using
donor vessels) by end-to-end attachment of splenic to internal iliac arteries
and superior mesenteric to external iliac arteries. Used with permission from
the Office of Visual Media, Indiana University.
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An alternative procedure for venous outflow is to anastomose the donor
portal vein to the recipient superior mesenteric vein, rather than to the
iliac veins. This procedure is called portal enteric drainage.
Postoperative Appearances
CT is performed when clinical findings suggest bowel obstruction or
abdominal infection. Because of the simultaneous kidney and pancreas
transplantations it is our usual practice to perform CT examinations without
administering IV contrast material in the early postoperative period; if
vascular disease or transplant necrosis is suspected, Doppler sonography or
gadolinium-enhanced MRI examination is typically performed. Positive oral
contrast material is used in CT studies to discern bowel from collections. The
donor duodenum is identified by a circular staple line (Figs.
2A and
2B). The donor duodenum may be
thick-walled. It is often unfilled with orally introduced contrast material,
even when the adjacent native jejunum contains contrast material. The donor
duodenum can be misinterpreted as an abscess (Figs.
2A and
2B). Mild self-limited
pancreatitis occurs in the early posttransplantation period in nearly all
cases (Fig. 3), resulting from
reperfusion injury, and typically involves the entire graft
[6]. Mural thickening of
surrounding bowel loops may occur. This finding is seen frequently and usually
resolves 3-4 weeks after transplantation.
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Fig. 2A —52-year-old man with donor duodenum simulating abscess. Axial
unenhanced CT image shows "fluid collection" (arrowhead)
that did not opacify with addition of oral contrast agent, contained gas
bubbles, and was incorrectly interpreted as perigraft abscess. Drains
(arrows) are noted adjacent to this structure.
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Fig. 2B —52-year-old man with donor duodenum simulating abscess.
Subsequent contrast-enhanced CT scan at similar level shows orally
administered contrast agent within structure surrounded by ring of staples
(arrowhead), confirming normal donor duodenum.
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Fig. 3 —36-year-old man 5 days after kidney-pancreas transplantation.
Axial CT shows moderate amount of fluid (black arrowheads) around
pancreas allograft (white arrow). Allograft shows enhancement. Note
peritoneal gas bubble (white arrowhead) in keeping with recent
surgery and renal transplant (black arrow). Such fluid collections
are commonly seen in first few weeks after transplantation and do not
correlate with graft survival.
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Bowel Complications
We reviewed 99 enteric drainage pancreas transplantations performed in 98
patients at our institution between January 1, 2003, and December 31, 2004.
Nineteen of these patients (19.4%) had bowel complications. Some of the
complications, such as anastomotic leaks, abscess, and adhesions, are common
to any major abdominal surgical procedure. Intraperitoneal placement of the
pancreas allograft creates the potential for internal hernia and bowel
strangulation. The frequency of bowel complications is summarized in
Table 1. For this report, we
have categorized bowel complications as small-bowel obstruction, anastomotic
complications, colonic complications, and miscellaneous complications.
Small-Bowel Obstruction
The two main reasons for postoperative small-bowel obstruction (SBO) after
pancreas transplantation are adhesions and internal hernias. Other less common
causes for bowel obstruction include obturation by bezoar, intussusception,
and external hernia. In our series, 10 patients (10.2%) presented with
high-grade SBO. Three of these patients had internal hernias, and the
remaining seven were found to have adhesion-related high-grade
obstruction.
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Fig. 4 —Sagittal-view line drawing shows internal hernia. Drawing
shows potential for internal hernia between donor duodenum/pancreatic
allograft and posterior peritoneum. Hernia occurs through mesenteric defect
used to attach donor duodenum to recipient jejunum. Used with permission from
the Office of Visual Media Indiana University)
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Internal Hernia
The intraperitoneal placement of the pancreas creates a potential site for
an internal hernia (Fig. 4).
Although an internal hernia could occur after other major abdominal surgery,
such as roux-en-Y gastric bypass, we have found a relatively high
incidence of this complication after enteric drainage pancreas
transplantation. The mesenteric defect after this transplantation is defined
by the aorta and iliac artery posteriorly, the small-bowel mesentery
superiorly, the pancreas and enteric anastomosis anteriorly, and the
pancreatic vascular anastomoses inferiorly. Jejunum adjacent to the
anastomosis with donor duodenum may become trapped posteriorly in relation to
the pancreas transplant. In our experience, CT enteroclysis is the best
technique for investigating posttransplantation SBO. The major findings on
conventional CT or CT enteroclysis (Figs.
5A,
5B, and
5C) are distended proximal
jejunal loops filled with orally or enterally introduced contrast medium;
distended small-bowel loops, which are usually not filled with contrast
medium, lying between the donor duodenum or pancreatic allograft and the iliac
vessels; and nondistended pelvic small-bowel loops, which may also be seen in
adhesion-related obstructions.
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Fig. 5A —29-year-old woman with internal hernia 8 months after
pancreas transplantation. Fluoroscopic part of CT enteroclysis shows beaked
end at site of small-bowel obstruction (arrowhead). Donor duodenum
(arrow) is attached to jejunum just proximal to obstruction.
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Fig. 5B —29-year-old woman with internal hernia 8 months after
pancreas transplantation. Reformats in coronal (B) and sagittal
(C) planes of isotropically acquired CT enteroclysis show
contrast-filled distended proximal jejunum (white arrows). More
distal distended bowel loops (white arrowhead, C) lie
posterior to donor duodenum (black arrows). Pelvic small-bowel loops
(curved arrows) are nondistended. Internal hernia, through mesenteric
defect, was noted during surgery on same day images were obtained.
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Fig. 5C —29-year-old woman with internal hernia 8 months after
pancreas transplantation. Reformats in coronal (B) and sagittal
(C) planes of isotropically acquired CT enteroclysis show
contrast-filled distended proximal jejunum (white arrows). More
distal distended bowel loops (white arrowhead, C) lie
posterior to donor duodenum (black arrows). Pelvic small-bowel loops
(curved arrows) are nondistended. Internal hernia, through mesenteric
defect, was noted during surgery on same day images were obtained.
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In addition, it may be possible to discern beaking of the herniated loop
and twisting of adjacent mesenteric vessels. It is important to make a timely
diagnosis of an internal hernia, which is essentially a closed-loop
obstruction. The rate of strangulation is much higher than with an
adhesion-related SBO [8].
Prompt surgery with repositioning of herniated loops was sufficient to ensure
bowel and allograft viability in our patients.
Adhesions
Intraperitoneal placement of the transplanted pancreas with resultant
pancreatitis may lead to bowel adhesions. The adhesions causing SBOs were in
the anterior abdomen (n = 4) or to the anterior aspect of the
transplanted kidney (n = 2). In cases of adhesive obstruction, unlike
with an internal hernia, distended loops were not seen posteriorly in relation
to the donor duodenum (Figs.
6A,
6B,
6C,
7A, and
7B). After other abdominal
surgery, the timing of a postoperative SBO has been suggested as a helpful
criterion in determining if an adhesion or an internal hernia is the likely
cause [9]. In our experience,
the chronologic onset of obstruction was not helpful in determining the cause.
Adhesion-related high-grade SBOs presented within a mean of 170 days after
surgery, with the earliest presentation on the 21st postoperative day.
Internal hernias presented between 57 and 367 days after surgery.
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Fig. 6A —20-year-old man with adhesive small-bowel obstruction 8
months after pancreas transplantation. Axial CT images show dilated
small-bowel loops (white arrow, B) with nondistended loops in
anterior abdomen (black arrows) adherent to parietal peritoneum. Note
absence of distended small-bowel loops between donor duodenum (black
arrowhead, A) and iliac vessels (white arrowhead,
A).
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Fig. 6B —20-year-old man with adhesive small-bowel obstruction 8
months after pancreas transplantation. Axial CT images show dilated
small-bowel loops (white arrow, B) with nondistended loops in
anterior abdomen (black arrows) adherent to parietal peritoneum. Note
absence of distended small-bowel loops between donor duodenum (black
arrowhead, A) and iliac vessels (white arrowhead,
A).
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Fig. 6C —20-year-old man with adhesive small-bowel obstruction 8
months after pancreas transplantation. CT enteroclysis performed next day with
positive enteral contrast enhancement shows long segment narrowing of anterior
loop of small bowel (black arrow) closely applied to anterior
peritoneum. Proximal bowel (white arrow) is distended. Appearances
were of adhesive obstruction confirmed during surgery on same day image was
obtained.
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Fig. 7A —28-year-old man with adhesive small-bowel obstruction 3 weeks
after pancreas transplantation. Axial CT images show distended small-bowel
loops (solid white arrows) and nondistended anterior loop (white
arrowhead, B). On image A, no bowel is seen between donor
duodenum (straight black arrow) and iliac vessels (curved black
arrow), confirming absence of internal hernia. On image B,
pancreas allograft (dashed white arrow) is edematous, which is
consistent with pancreatitis. Patient subsequently underwent adhesionolysis.
Incidental note of thrombosed vessel (black arrowhead, B) is
seen adjacent to transplant. This is common postoperative finding, caused by
thrombosis of distal donor superior mesenteric artery, and is of no clinical
significance.
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Fig. 7B —28-year-old man with adhesive small-bowel obstruction 3 weeks
after pancreas transplantation. Axial CT images show distended small-bowel
loops (solid white arrows) and nondistended anterior loop (white
arrowhead, B). On image A, no bowel is seen between donor
duodenum (straight black arrow) and iliac vessels (curved black
arrow), confirming absence of internal hernia. On image B,
pancreas allograft (dashed white arrow) is edematous, which is
consistent with pancreatitis. Patient subsequently underwent adhesionolysis.
Incidental note of thrombosed vessel (black arrowhead, B) is
seen adjacent to transplant. This is common postoperative finding, caused by
thrombosis of distal donor superior mesenteric artery, and is of no clinical
significance.
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Intermittent low-grade obstructions or nonobstructive adhesions are seen on
conventional CT or CT enteroclysis more frequently than are high-grade
adhesive SBOs. Features of nonobstructive adhesions include acute angulation
of small-bowel loops, stretching of loops with air trapped in valvulae
conniventes, asymmetric thickening of the small-bowel wall, small-bowel loops
closely applied to the anterior peritoneum, and thickening of the anterior
peritoneum [8]
(Fig. 8). We routinely comment
on these findings because some of these patients have intermittent abdominal
pain that improves after surgical adhesionolysis.
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Fig. 8 —52-year-old man with nonobstructive bowel adhesions 9 weeks
after pancreas transplantation. Contrast-enhanced axial CT, with orally
administered contrast agent, shows multiple loops of small bowel closely
applied to anterior abdominal wall. Parietal peritoneum is thickened in parts
(black arrowhead). Asymmetric thickening of small-bowel loops
(white arrowhead) is shown.
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Anastomotic Complications
Leakage at the duodenojejunal anastomosis with peritonitis
(Fig. 9) or localized abscess
formation is an uncommon but serious complication. Occasionally, difficulty
occurs in separating fluid collections as a result of anastomotic leaks from
pancreatitis-related collections. Presence of an orally administered contrast
medium in a collection is highly suggestive of the former. An enterocutaneous
fistula may occur if the leak is not diagnosed and treated promptly. In our
experience, CT enteroclysis is more likely to depict an anastomotic leak or a
small-bowel fistula (Figs. 10A
and 10B) than conventional
CT.
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Fig. 9 —34-year-old woman with peritonitis 6 weeks after pancreas
transplantation. Patient had stormy postoperative course characterized by
anastomotic leak, drainage of fluid collections, repeat laparotomy, and
continued fever. Contrast-enhanced axial CT image, with IV-administered
contrast agent, shows fluid collection (arrows) surrounded by
enhancing peritoneum. Abdominal wound was left open after prior surgery, to
prevent abdominal compartment syndrome. Note donor duodenum surrounded by
staples (arrowhead). Peritonitis was diagnosed and confirmed during
surgery on same day image was obtained.
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Fig. 10A —36-year-old man with enterocutaneous fistula 6 weeks after
pancreas transplantation. Contrast-enhanced axial CT image, with orally and
IV-administered contrast media, shows possible track (arrow) through
abdominal wall extending into open wound. Edema is seen in head of allograft
(arrowhead), which is consistent with pancreatitis.
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Fig. 10B —36-year-old man with enterocutaneous fistula 6 weeks after
pancreas transplantation. Axial image from CT enteroclysis performed next day,
at same level as in A, shows enterally introduced contrast material has
extravasated into subcutaneous tissue (arrow) indicating
enterocutaneous fistula. Note pancreatic allograft (white arrowhead)
and surgical drain (black arrowhead).
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Fig. 11 —36-year-old man with pseudomembranous colitis 4 weeks after
pancreas transplantation. Patient had diarrhea and right colon
(arrowhead) is considerably thickened. Stool cultures were positive
for Clostridium difficile. Incidentally, small-bowel loops are
closely applied to anterior abdominal wall (black arrow) and
thickening of normally invisible anterior parietal peritoneum (white
arrow) is seen, which indicates nonobstructive adhesions.
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Fig. 12A —49-year-old woman with bowel necrosis 5 weeks after pancreas
transplantation. Contrast-enhanced axial CT image, with IV-administered
contrast agent, shows diffuse small-bowel mural thickening (solid black
arrow) and ascites (arrowhead). Bubble of free peritoneal
(white arrow) gas is noted, which may have been caused by focal bowel
perforation, but was clinically thought to be introduced via surgical drain.
CT features, although nonspecific, raise suspicion of early bowel ischemia.
Patient also had necrotic pancreatic allograft. Note donor duodenum
(dashed arrow) anterior to iliac vessels.
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Fig. 12B —49-year-old woman with bowel necrosis 5 weeks after pancreas
transplantation. Unenhanced axial CT obtained 2 weeks later, after further
surgical intervention, shows diffuse pneumatosis (arrowheads) and
high-density hemorrhagic ascites (arrows). Patient died 1 day later,
and postmortem examination showed extensive small-bowel infarction.
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Colonic Complications
Colonic complications after transplantation are uncommon and include
cytomegalovirus colitis (n = 1) and antibiotic-associated
Clostridium difficile colitis (n = 3)
(Fig. 11).
Miscellaneous Complications
Bowel necrosis may occur after a strangulation obstruction. Early CT
findings of bowel ischemia are nonspecific and include wall thickening,
mesenteric vessel engorgement, and ascites (Figs.
12A and
12B). More advanced ischemia
is heralded by mesenteric vessel blurring, hemorrhagic ascites, enhancement of
thickened wall on delayed images, pneumatosis, and mesenteric or portal venous
gas. We saw two cases of bowel necrosis (Figs.
12A and
12B). The cause was unclear in
both patients, who died despite surgical resection of the affected small
bowel.
Small-bowel hemorrhage was seen in one patient, who presented with
abdominal pain and melena. A CT scan showed marked recipient jejunal wall
thickening. The patient was treated conservatively and improved without
surgery. No cause of the bowel hemorrhage was identified. Rarely, an arterial
graft duodenal fistula may be a source of massive gastrointestinal bleeding
[10].
Isolated case reports have been published of graft-versus-host disease
after pancreatic transplantation because of incompatibility of minor RBC
antigens [11,
12]. Exclusion of donor spleen
has virtually eliminated the risk of this complication, and we saw no cases of
this complication in our group of patients.
Conclusion
Prompt detection and treatment of bowel complications after pancreas
transplantation are essential for graft survival. In this report, we have
discussed a range of postoperative bowel complications. An internal hernia is
a relatively common and important cause of SBO after enteric drainage pancreas
transplantation, and the risk for bowel ischemia is relatively high after an
internal hernia. The radiologist needs to be able to distinguish this entity
from simple adhesive SBOs. Although sonography and MR angiography are the main
techniques for diagnosing vascular and allograft-related complications, CT
and, occasionally, CT enteroclysis are the primary imaging techniques for
diagnosing bowel-related complications.
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Abstract
Introduction
