The margins of the peritoneum are mobilized in order to close the peritoneal floor securely. The peritoneum is grasped with toothed forceps and mobilized by the surgeon's hand or by blunt gauze dissection (Figure 15). The peritoneum in the pouch of Douglas is mobilized as widely as possible to facilitate closing the pelvic floor. The location of the ureters is reaffirmed from time to time to avoid their accidental ligation or injury. In females the uterus and adnexa may be used, if necessary, to close the new pelvic floor. At times it may be possible to close the pelvic floor in a straight line, but, more frequently, a radial type of closure is necessary to avoid undue tension on the suture line (Figure 16). All raw surfaces should be covered whenever possible. The omentum is placed over the peritoneal closure (Figure 17). Some make no attempt to close the peritoneum and rely on muscular closure.
When the patient's anatomy permits, a pedicled omental flap based on the left or right gastroepiploic artery can be created and laid into the pelvic defect. When enough omentum is available, this both fills the volume of the pelvis and covers the raw surfaces of the dissection. Some surgeons prefer to anchor the sigmoid to the lateral parietal peritoneum in order to close the left lumbar gutter and to avoid the possibility of an internal hernia. Whenever possible, these sutures should include the fat tabs or mesentery to avoid possible perforation of the bowel.
The omentum is returned to the region of the new pelvic floor and the table is leveled. The colostomy is created through a separate 3-cm (1¼ in.) opening selected and marked prior to surgery. In general, it is midway between the umbilicus and the left anterior superior spine (Figure 18). As this colostomy will be a permanent one, it is wise to choose the site in consultation with the enterostomal therapist. The adhesive ring of the colostomy bag must conform to the contour of the abdomen and must be secure when the patient is standing, bending, or sitting. After excision of the circle of skin, a two-finger-sized opening is made through the abdominal wall. The colon is grasped with Babcock forceps and brought out through the opening without undue rotation of the mesenteric blood supply. Late herniation about the colostomy can be minimized by tailoring the opening in the abdominal wall such that the colon plus one finger is a snug fit.
The abdominal wall is closed with interrupted 00 silk sutures or 00 synthetic absorbable sutures. Subcuticular closure of the skin should be considered since this ensures a sealed wound about an area repeatedly contaminated from the adjacent colostomy. In patients with marked obesity or cachexia, retention sutures may be utilized. The exteriorized portion of the bowel is then inspected to make certain that active pulsation is present in its blood supply. Sufficient intestine should have been provided to ensure at least 5 to 6 cm of viable bowel protruding above the skin level (Figure 19).
Immediate opening of the colostomy after the remainder of the wound has been covered is preferred to leaving a clamp on the exposed area completely obstructed intestine for several days. The stapled suture line is excised and the mucosa within the lumen of the bowel grasped with one or two Babcock forceps to provide fixation for the eversion of the mucosa (Figure 19). It may be necessary to excise several large fat tabs and additional thickened mesentery, especially in the obese patient, to facilitate the eversion of the mucosa. The mucosa is anchored to the margin of the skin with interrupted sutures or 000 synthetic absorbable sutures on a curved cutting needle (Figure 20). A sufficient number of sutures is taken to control bleeding as well as to seal off the subcutaneous tissue about the colostomy (Figure 21). The mucosa should be pink in color to ensure viability. The surgeon may insert a gloved finger into the colostomy to make certain the lumen is free and adequate without undue constriction within the abdominal wall. When the operation is complete, an ostomy appliance is applied.