The small intestines are walled off and a self-retaining retractor is inserted into the wound. The peritoneum of the pelvic colon is freed from the region of the sigmoid downward on either side (figure 3). It is important at this point to identify and isolate both ureters and the spermatic or ovarian vessels. The peritoneum is divided anterior to the rectum at the level of the base of the bladder or cervix. The growth can be further mobilized by mesorectal dissection (Chapter 59, figure 8). After the peritoneal attachments have all been divided, and the rectum is freed both posteriorly and anteriorly, it is possible to bring this growth up into the wound and gain considerable distance as a result of freeing and straightening the rectum (figures 1 and 2). The blood supply to the distal segment from the inferior hemorrhoidal vessels is adequate, should the middle hemorrhoidal vessels be ligated to ensure additional mobilization. The inferior mesenteric artery is ligated at the level of the superior hemorrhoidal vessels or as it arises from the aorta (figure 3) and the inferior mesenteric vein is divided. This provides maximum lymphatic lymph node removal and gives additional mobility to the descending colon. The blood supply to the colon must now come from the middle colic artery through the marginal vessels of Drummond (figure 3).
The bowel should be prepared for division at least 5 cm below the gross lower limits of the growth to assure removal of all adjacent lymph nodes. A Stone or a Pace-Potts anastomosis clamp is applied across the previously prepared site of division of the bowel, and a long, right-angle clamp may be utilized for the proximal clamp (figure 4). The bowel is divided between the clamps. The bowel containing the growth is then brought outside the wound, and clamps are applied to the previously prepared site well above the lesion (figure 5). The surgeon must now determine that the upper segment of the bowel is sufficiently mobile to be brought down for anastomosis without tension. In order to accomplish this, it may be necessary to divide the lateral peritoneal attachment of the left colon up to and including the splenic flexure. Unless the sigmoid is very redundant, the left half of the transverse colon along with the splenic flexure must be mobilized. The midline incision is extended at this point to ensure a good exposure, since undue traction on the colon may tear the capsule of the spleen. The splenic flexure is also mobilized, as in Chapter 57. The lesser sac is entered after the splenic attachments to the colon have been divided. The greater omentum is freed from the transverse colon as shown in Chapter 27, figure 1. Extra mobility and length of bowel are provided until repeated trials clearly demonstrate that the proximal segment will easily reach the site of anastomosis. The adequacy of the blood supply should be determined even when the bowel is extended down into the pelvis preliminary to the anastomosis.
The serosa along the mesenteric border of the upper segment should be cleared of fat for at least 1 cm proximal to the Pace-Potts clamps (figure 5). Likewise, the margins and especially the posterior wall of the lower segment must be cleared of fat adjacent to the Pace-Potts clamp (figure 5). Careful dissection with repeated application of small clamps may be necessary to accomplish a clean serosal boundary of 1 cm adjacent to the clamp in preparation for a safe anastomosis. Following this, the two ends of the clamps are approximated and then manipulated so that a posterior serosal layer of 000 silk can be placed easily (figure 6). The ends of these sutures are cut, except those at either angle, which are retained for traction. As a preliminary to removing the clamp, the field is walled off with gauze, and an enterostomy clamp is gently applied to the upper segment to prevent gross soiling (figure 6). The crushed contents of the clamps may be excised. The lower clamp is then removed, and the crushed margin of bowel is excised and opened (figure 7). Suction is instituted to avoid any gross contamination of the field. Fine silk sutures may be inserted for traction in the midportion of the lower opening and at either angle. These traction sutures tend to facilitate the anastomosis (see Chapter 63, figures 16 and 17). The posterior mucosal layer is approximated with several Babcock forceps, and the mucosa is approximated with interrupted 000 silk sutures. The anterior mucosal surface is closed with interrupted 000 silk sutures of the Connell type, with the knot on the outside. The mucosa may be closed with a continuous 000 synthetic absorbable suture (figure 8) rather than interrupted silk sutures. Following this, the anterior serosal layer is carefully placed, using interrupted Halsted sutures of fine 000 silk (figure 9). The peritoneum is anchored adjacent to the suture line. The patency of the anastomosis, as well as the lack of tension on the suture line, should be tested. The peritoneal floor is closed with interrupted absorbable sutures (figure 10). The raw surfaces are covered by approximating the mesenteric margin of the sigmoid to the right peritoneal margin (figure 10). The sigmoid is loosely attached to the left pelvic wall by anchoring the fat pads, not bowel wall, to the left peritoneal margin to prevent subsequent tension on the anastomosis as well as to cover the raw surfaces. A transverse colostomy or diverting loop ileostomy (Chapter 51) should be considered if there is any suspicion regarding the technical perfection of the anastomosis. A drain may be inserted into the left side of the pelvis and brought out at the lower angle of the wound. Some operators prefer to have a rectal tube in place, which can be guided up beyond the anastomosis to assist in decompressing the bowel during the early postoperative period. The rectal tube is anchored in position by a silk suture placed at the anal margin. Some prefer to use a surgical stapling instrument for the anastomosis. See Chapter 62.