The ileal pouch-anal anastomosis (IPAA) (also called ileoanal anastomosis, ileoanal reservoir, and ileoanal pull-through) is a technique originally described by Ravich and Sabiston in 1948. It was devised to remove the entire colon while maintaining intestinal continuity, avoiding a permanent ileostomy, and maintaining continence. The operation is usually performed in patients with ulcerative colitis or familial ade-nomatous polyposis syndrome (FAPS). Patients with Crohn's disease are not good candidates for IPAA because of the potential for recurrent disease, including fistulas, strictures, and abscesses, and a subsequent higher incidence of pouch failure. A proctocolectomy is performed to about 8 cm above the peritoneal reflection with a rectal mucosectomy. The terminal ileum is used to construct an ileal reservoir or pouch to maintain continence. Various ileal pouch configurations have been used, including J, S, W, and lateral isoperistaltic (side-to-side) types. Straight ileal pull-throughs are generally not performed because of excessive stool frequency. The J and S shapes are currently the most widely used configurations (Fig. 6.18). The two-limbed J-shaped pouch is relatively simple to construct, is adaptable to stapling techniques, and is easily emptied. The three-limbed S-shaped pouch has a larger reservoir than the J-shaped pouch, but 40 to 50% of patients experience
spontaneous defecation and incomplete evacuation . After the reservoir has been constructed, the mucosa is dissected from the retained rectum, and an ileoanal anastomosis is created with the efferent limb of the reservoir. A temporary loop ileostomy, performed to allow healing of the anastomosis and suture lines, is generally closed after 6 to 8 weeks.
Radiographic examination of the pouch, by pouchography, CT imaging, and/or 111In-labeled leukocyte scintigraphy, is necessary before closure of the ileostomy to exclude postoperative complications. Kremers et al. advocate studying the pouch by means of a 16 to 20F Foley catheter introduced through the anus . Barium is administered under fluoroscopic guidance and anteroposterior, lateral, and oblique views are obtained in full distention. These authors advocate the use of barium rather than water-soluble contrast medium because barium permits detection of smaller leaks. Additional views are then obtained after catheter removal and spontaneous evacuation of the reservoir to identify leakage, which may not be identified on the filled films, and to evaluate the emptying function of the reservoir. On the other hand, Thoeni et al. advocate antegrade filling of the pouch via the ileostomy, since they feel that this technique better distends the pouch . Thoeni et al. also suggest that CT imaging should be the initial examination; if an abscess is identified then, no other radiographic examination need be performed.
On pouchography, the normal S pouch has a globular appearance with an efferent limb (Fig. 6.19). The J pouch characteristically has a raphe corresponding to the suture lines between the two segments of the pouch (Fig. 6.20). J pouches can vary in size, shape, and pattern of external impressions . In most patients, spiral folds run from the main portion of the pouch to the pectinate line. A lucency resembling a polyp may be identified at the lower edge of the interpouch suture. An impression from the mesentery is another variant that may be confused with a mass.
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