The colon may be constricted, friable, and quite vascular, with firm attachments to the omentum. Gentle traction is applied to avoid tearing the friable bowel with resulting gross contamination. The mesentery of the colon can be divided and blood vessels ligated relatively near the bowel wall, except in diffuse polyposis, where there is always a possibility of metastases to regional lymph nodes. It is judicious to have the pathologist evaluate the entire specimen as soon as possible.
Before proceeding with the removal of the mucosa from the lower segment and before constructing the ileal reservoir, it is essential that sufficient ileum has been mobilized to construct the pouch. Approximately 50 cm of terminal ileum is required for the construction of the ileal reservoir. Such mobilization is accomplished by dividing the ileocolic vessels and the mesentery down to near the arcade of vessels at the very end of the ileum, but none of the latter is ligated (figure 3). It may be necessary to evaluate the mobility of the small bowel all the way up to the ligament of Treitz with division of any bands that tend to limit the mobility of the small intestine (figure 4). Incisions within the posterior peritoneum may be worthwhile to provide added mobility. Some divide the last ileal arcade (figure 4). The adequacy of the blood supply involved should be evaluated frequently to be certain a vigorous blood supply is sustained to the end of the mobilized ileal terminal. The end of the proposed pouch should reach at least to the pubis, and preferably to the edge of the Bookwalter ring being used for retraction.
The dissection below the rectosigmoid junction is carried out close to the bowel wall to avoid damage to the presacral and parasympathetic nerves. The rectal stump is washed out with povidone-iodine, and the bowel divided at the anorectal junction. This leaves a stump about 3 to 4 cm in length (figure 5). Some prefer to have a longer rectal anal stump, which requires resection of the rectal mucosa from above rather than entirely through the anus. Others use a stapling instrument for closure of the rectal stump.
Many surgeons advocate leaving about 2 cm of mucosa above the columns. Recurrence of inflammatory bowel disease and malignant degeneration are possible and careful follow-up is essential. In general, avoidance of rectal dilatation or eversion of the stump plus a high level of anastomosis results in better fecal continence. In patients with high-grade dysplasia in the rectum, a traditional mucosectomy may be a better option, as it removes all the mucosa. If this technique is done, a hand-sewn ileoanal anastomosis would be required. The J pouch is constructed by rotating the terminal ileum clockwise to create a “J” shape (as seen from anteriorly) 15 cm long. The anterior ends are held by semicircular 000 silk sutures (figure 6). The length is then checked as described above to ensure it will reach the pelvis. The distal antimesenteric end of the pouch is opened with electrocautery. A linear stapler is then inserted and fired, creating a pouch from the two limbs (figure 7). Multiple firings are used to complete the full length of the pouch (to reach the upper end, the distal end is telescoped onto the stapler). A 2-0 Prolene suture is then used to create a “whip-stitch” purse-string suture around the opening in the tip of the pouch. An anvil of the circular stapler is then inserted and the purse-string tied around it (figure 8). The anvil must sit so that the antimesenteric aspect of the ileum is draped across it. The circular stapling instrument is then inserted gently into the rectum by an assistant. It is advanced up to the level of the stapled rectal stump. The sharp spike then pierces through the stump just posterior to the staple line and it is approximated with the anvil (figure 9).The device is then closed and fired, taking care not to include adjacent structures such as the vagina. Naive or too-vigorous insertion of the circular stapler instrument will rip through the very short rectal stump and make the procedure much more difficult. Figure 10 demonstrates the completed J pouch with ileorectal stump anastomosis.
If the rectal mucosa is severely diseased, then a complete mucosal proctectomy may be indicated. The mucosa is excised from the dentate line up to include the 3 or 4 cm of mucosa in the rectal stump. Some prefer to outline the dentate line with electrocoagulation followed by the submucosal injection of 1:300,000 adrenaline solution (figure 11). This tends to elevate the mucosa and facilitate the dissection in a more bloodless field. All mucosa must be completely removed. This dissection is often the most time-consuming part of the technical procedure and must be done with the greatest care (figure 12). The underlying muscle and nerves must not be injured. A dry field is essential.
Some prefer to grasp the stump with a Babcock forceps in the anus and everted out the anus (figure 13). This facilitates the removal of the mucosa under direct vision but may result in poor fecal continence (figure 14).
Others prefer to divide the mucosa at the top of the columns of Morgagni (figure 5). This avoids telescoping the rectal stump and lessens the possibility of nerve injury where the patient may not be able to differentiate stool from flatus postoperatively.
If a mucosal proctectomy is performed, then a hand-sewn ileoanal anastomosis must be completed. This is demonstrated on page 235 in this chapter.
The adequacy of the blood supply to the reservoir is again double-checked. Two interrupted sutures with needles attached (figure 15) are anchored on each side of the two-finger opening in the reservoir. These sutures are passed by the surgeon down through the anus, and the reservoir is placed in the proper position from above.
The two sutures on each side are then anchored to either side of the opening at the level of the dentate line (figure 16). An additional suture is placed in the midline anteriorly and posteriorly. Eight or ten additional sutures may be required to ensure an accurate anastomosis. These sutures include the full thickness of the ileal wall, as well as a portion of the internal sphincter (figure 17).
Any openings in the mesentery are closed with interrupted sutures to avoid intestinal hernia. The pelvic peritoneum is closed about the pouch to avoid twisting or displacement. A suture may be placed to anchor the pouch to each side of the muscular rectal cuff to secure the pouch in position and lessen the possible tension on the suture in the dentate line anastomosis. Some prefer to insert a rubber drain between the wall of the pouch and the rectal cuff. The rubber tissue drain is brought out anteriorly.
While it is tempting to avoid an ileostomy, fewer postoperative complications result if a complete diversion of the fecal stream is accomplished by ileostomy. The defunctioning ileostomy is performed through a small opening in the left lower quadrant about 40 cm from the pouch (figure 18). It is advisable to ensure complete diversion of the fecal stream (figure 19) by intussuscepting up the proximal limb or stoma over the rod (see also Chapter 51).