AJR 2003; 180:999-1002
© American Roentgen Ray Society
Radiology of Ileal Pouch–Anal Anastomosis Surgery
Richard E. Seggerman1,
Michael Y. Chen1,
Gregory S. Waters2 and
David J. Ott1
1 Department of Radiology, Wake Forest University School of Medicine, Medical
Center Blvd., Winston-Salem, NC 27157-1088.
2 Department of Surgery, Wake Forest University School of Medicine,
Winston-Salem, NC, 27157.
Received July 16, 2002;
accepted after revision August 27, 2002.
Address correspondence to D. J. Ott.
Introduction
Surgery plays a major role in the treatment of patients with ulcerative
colitis and familial adenomatous polyposis of the colon. The surgical
procedure has been accomplished by performing a proctocolectomy and an end
ileostomy, leaving a permanent stoma. Ileal pouch–anal anastomosis
surgery has emerged as a means to cure the disease while maintaining a normal
route of defecation, thus preserving a more normal lifestyle. The surgical
procedure involves a subtotal proctocolectomy, an ileal reservoir or pouch,
and an ileal pouch–anal anastomosis
[1]. We discuss the
indications, surgical procedure, and radiologic evaluation of ileal
pouch–anal anastomosis after surgery.
Patient Selection
Ileal pouch–anal anastomosis is the operative procedure of choice for
patients with ulcerative colitis and familial adenomatous polyposis of the
colon. There are absolute and relative contraindications to ileal
pouch–anal anastomosis surgery. Because the pouch is created from the
terminal ileum, Crohn's disease is an absolute contraindication. A successful
outcome is contingent on adequate anal sphincter function. Therefore, age
older than 65 years is a relative contraindication because of poor sphincter
control. Cancer of the rectum or anus is an absolute contraindication. The
procedure may not be possible in obese patients because of technical
difficulties.
Surgical Options
A two-step procedure is performed in most patients, particularly those with
ulcerative colitis. The first step includes a colectomy, ileal pouch creation,
ileal pouch–anal anastomosis, and diverting ileostomy. A temporary
diverting ileostomy is created initially to reduce the risk of sepsis. The
second step includes taking down the ileostomy 8–12 weeks later.
Radiologic imaging is performed in this interval to assess postsurgical
complications, if present. A one-step procedure can be considered in patients
with familial adenomatous polyposis who are in excellent health. A three-step
procedure may be used in more seriously ill patients, which involves an
initial colectomy with a Hartmann's pouch, ileal pouch creation and ileal
pouch–anal anastomosis at a later time, and takedown of the ileostomy as
a final operation.
Surgical Technique
The most common design of the ileal reservoir is a J-shaped pouch that is
easy to construct, usually reaches the anal verge without tension, stores an
adequate volume, and empties well. Alternatively, S- or W-shaped pouches may
be constructed to reach the dentate line easily under rare circumstances. A
30-cm ileal J-pouch is prepared by folding the terminal 15 cm of the ileum
back on itself. A stapling device is introduced down both limbs of the J via
an enterotomy at the apex and is fired twice. Stapling serves both to cut the
walls between the two loops and to staple the loops together. The apical
enterotomy can later serve for the anastomosis. The crotch of the J is secured
with sutures. A rectal mucosectomy may be performed via a perineal approach,
leaving a 2- to 4-cm rectal muscle cuff. The apex of the pouch can then be
secured to the rectal stump. The length of the terminal ileal stump is
variable. A temporary diverting loop ileostomy is created in the right lower
quadrant by pulling a tension-free loop of ileum proximal to the pouch through
an abdominal wall incision. The proximal limb is everted to create a 2-cm
spout (Fig. 1A,
1B).
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Fig. 1B. —Diverting loop ileostomy. Loop ileostomy in 35-year-old woman
who underwent ileal pouch–anal anastomosis because of familial polyposis
and colon cancer. CT scan shows proximal (arrow) and distal
(arrowhead) limbs of loop ileostomy.
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Radiologic Evaluation
Contrast Techniques and Findings
Water-soluble contrast enema examination and fistulography are routinely
performed just before the ileostomy takedown to evaluate for an anastomotic
leak or stricture [2]. These
findings may then be addressed at surgery. The anteroposterior and lateral
scout views will show the characteristic dual row of pouch staples and the
circle of staples at the ileal pouch–anal anastomosis
(Fig. 2) (unless a hand-sewn
technique was used). Malcolm et al.
[3] showed the value of
recognizing the presence or absence of an intact ring of staples at the ileal
pouch–anal anastomosis on preliminary radiographs; those authors
reported that disruption of the staples of the ileoanal anastomosis is a
sensitive (88%) but not a specific (57%) predictor for subsequent pelvic
infection.
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Fig. 2. —33-year-old man who underwent subtotal proctocolectomy and
ileal pouch–anal anastomosis. Radiograph of pelvis shows characteristic
dual row of pouch staples (arrowheads) and circular ileal
pouch–anal anastomosis staples (arrow).
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Documenting the presence or absence of all radiodense objects on an initial
radiograph is important in evaluating extraluminal extravasation of contrast
material on subsequent images obtained after contrast injection. The pouch and
the proximal ileum should be opacified with contrast material to the level of
the ileostomy (Fig. 3A,
3B,
3C). A stump of the terminal
ileum of variable length may extend from the J-pouch. The length of the stump
is a result of the variable degree of buckling of the bowel that occurs when
the pouch is created with the stapling device. The appearance of a pseudoleak
resulting from partial opacification of the terminal ileal stump can be
overcome by adequate distention of the pouch and the ileal stump. The presence
of extraluminal contrast material suggests sinus tracts, fistulas, or
abscesses. An abscess cavity may also be indicated by the presence of
extraluminal gas. The ileoanal anastomosis is also assessed for the presence
of a stricture.
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Fig. 3A. —Ileal pouch–anal anastomosis in 57-year-old man with
ulcerative colitis. Anterior (A) and lateral (B) radiographs of
ileoanal pouch show proximal limb (arrow, B) and blind ileal
stump (arrowhead, B).
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Fig. 3B. —Ileal pouch–anal anastomosis in 57-year-old man with
ulcerative colitis. Anterior (A) and lateral (B) radiographs of
ileoanal pouch show proximal limb (arrow, B) and blind ileal
stump (arrowhead, B).
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Fig. 3C. —Ileal pouch–anal anastomosis in 57-year-old man with
ulcerative colitis. Line drawing of A shows that apex of ileal
reservoir is brought down to anal area and anastomosed to dentate line mucosa
(arrow).
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CT Technique and Findings
CT may be performed at any time after surgery if postoperative
complications are suspected. Water-soluble contrast material may be
administered per anus if necessary for problem solving. The pouch is
identified on CT as a fluid-filled structure with a characteristic row of
staples oriented 180° apart from each other. The pouch may be displayed in
a coronal or an axial orientation and can contain variable amounts of air
(Fig. 4A). The terminal ileal
stump and ileostomy can be followed up on serial images and may be
differentiated from an abscess. After the ileostomy takedown, the pouch will
opacify with contrast material administered orally
(Fig. 4B). The presence of
extraluminal contrast material, fluid, or air should be identified. If a sinus
tract or fistula is suspected, injection of water-soluble contrast material
per anus may be helpful. The presence of stranding in the peripouch mesenteric
fat is more commonly associated with infectious surgical complications but may
also be a result of the chronic inflammatory changes of ulcerative colitis
[4,
5].
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Fig. 4A. —Ileal pouch–anal anastomosis in 46-year-old woman who
underwent proctocolectomy for familial polyposis and colon cancer. CT scan
shows ileal pouch with air (arrow) in pouch before ileostomy
(arrowhead) closure.
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Fig. 4B. —Ileal pouch–anal anastomosis in 46-year-old woman who
underwent proctocolectomy for familial polyposis and colon cancer. CT scan
shows ileal pouch (arrow) after ileostomy closure. Pouch was
opacified with contrast material.
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Complications
Complications of ileal pouch–anal anastomosis surgery include
small-bowel obstruction, pouch fistula, anastomotic dehiscence, anastomotic
stricture, pelvic abscess, pouch failure, perianal fistula, and pouchitis
[1,
6]. Small-bowel obstruction is
the most common complication, with a subacute obstruction occurring in as many
as 37% of patients within 3 years of surgery
[1,
7]. The incidence of septic
complications has ranged from 5% to 24%
[1,
7]. Sepsis may result from
pouch or anastomotic dehiscence or from an infected pelvic hematoma. An
anastomotic leak or pouch leak may result in a fistula (Fig.
5A,
5B,
5C) or sinus tract. A leak at
initial pouchography is a specific (81%) but insensitive (56%) finding for
predicting pelvic collections
[2,
3]. Therefore, the presence of
a leak is a useful feature to delay takedown of the ileostomy; the absence of
a leak has a high negative predictive value (76%)
[3]. Anastomotic strictures
have been reported to occur in 8–14% of patients
[1,
7,
8] (Fig.
6A,
6B). Strictures usually
respond well to dilatation. Pouchitis is a vague clinical syndrome of
uncertain cause consisting of crampy abdominal pain, diarrhea, malaise,
urgency, incontinence, and low-grade fever. Pouchography findings of pouchitis
include spicules, thickening of folds, and pouch spasm
[5]. CT findings include a
thickened pouch wall (>3 mm) with peripouch inflammatory stranding.
111In-labeled WBC scintigraphy shows increased uptake in the
location of the pouch. Sensitivity for the detection of pouchitis is reported
to be 80% for scintigraphy, 71% for CT, and 53% for pouchography
[5].
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Fig. 5A. —Abscess in 29-year-old woman with ulcerative colitis who
underwent ileal pouch–anal anastomosis. CT scan (A) and cutaneous
fistulogram (B) show abscess (A) with cutaneous fistula
(arrowheads) and enteric fistula (arrows).
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Fig. 5B. —Abscess in 29-year-old woman with ulcerative colitis who
underwent ileal pouch–anal anastomosis. CT scan (A) and cutaneous
fistulogram (B) show abscess (A) with cutaneous fistula
(arrowheads) and enteric fistula (arrows).
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Fig. 5C. —Abscess in 29-year-old woman with ulcerative colitis who
underwent ileal pouch–anal anastomosis. Contrast enema shows contrast
material filling pouch (P) and vagina (V), indicating pouch–vaginal
fistula.
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Fig. 6A. —Ileal pouch–anal anastomotic stricture in 29-year-old
woman with familial polyposis who underwent ileal pouch–anal
anastomosis. Anteroposterior (A) and lateral (B) radiographs of
contrast enema reveal ileal pouch–anal anastomotic stricture
(arrows) that was subsequently successfully dilated during ileostomy
takedown procedure.
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Fig. 6B. —Ileal pouch–anal anastomotic stricture in 29-year-old
woman with familial polyposis who underwent ileal pouch–anal
anastomosis. Anteroposterior (A) and lateral (B) radiographs of
contrast enema reveal ileal pouch–anal anastomotic stricture
(arrows) that was subsequently successfully dilated during ileostomy
takedown procedure.
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Conclusion
Ileal pouch–anal anastomosis surgery preserves transanal defecation
for patients with ulcerative colitis or familial polyposis. Radiologists must
be aware of the surgical procedure, normal appearances, and its potential
complications.
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Introduction
Patient Selection
