The anesthesia, position, and abdominal incision and exposure are determined by the colon operation being performed. When markings are made preoperatively, they should be scratched gently into the skin with an “X” prior to skin preparation. If this is not done, at the end of a long and difficult case, the inked markings will likely be gone. Upon completion of the colon anastomosis and prior to closure of the abdomen, the ostomy site is revisited. The cut edge of the abdominal wall, namely, the linea alba in the midline incision, is grasped with Kocher clamps and retracted to the central position it will occupy after closure. In patients with a thick abdominal wall, an additional clamp may be placed on the dermis to hold the abdominal wall in its usual alignment. A 3-cm circle of skin is excised and the dissection is carried down through the subcutaneous fat to the anterior fascia of the rectus muscle. A two finger–sized opening is made through the fascia. Some prefer a single slit, while others make a cruciate incision. The rectus muscle is spread or retracted medially. Care should be taken not to injure the epigastric vessels that run deeply in the center of this muscle. Another two finger–sized opening is made through the posterior sheath and peritoneum.
An appropriate segment of terminal ileum, usually about 1 ft or so proximal to the ileocecal valve, is selected. This section of small bowel must have sufficient mobility to reach through the abdominal wall without stretch or tension. It should also be proximal enough to allow side-to-side anastomosis at the time of ostomy closure. A blunt Kelly hemostat is used to create a mesenteric opening just beneath the wall of the ileum. A segment of umbilical tape or a soft rubber Penrose drain is drawn through the opening (Figure 2) and a seromuscular absorbable suture is placed to mark the proximal limb of the ileum. The opening in the abdominal wall is checked again for size relative to the thickness of the ileal loop and its mesentery. In general, a two finger–sized opening is adequate. The tape and the ileal loop are brought through the abdominal wall using gentle traction with a rocking motion (Figure 3). The loop is oriented in a vertical manner with the active proximal limb and its marking suture placed at the cephalad or 12 o'clock position. The loop ileostomy should protrude about 5 cm above the level of the skin. A plastic ostomy rod replaces the umbilical tape or Penrose drain to prevent retraction following closure of the abdomen. The caudal or inactive side of the loop is opened transversely for two-thirds of its diameter in a position about halfway up from the skin level to that where the tape or Penrose drain penetrates the mesentery. Submucosal bleeding sites are secured with fine 0000 silk ligatures or cautery. The distal inactive stoma is matured first by placing fine 0000 absorbable sutures that traverse the entire thickness of the ileal bowel wall (Figure 4). This suture is completed as a transverse subcuticular bite beneath the skin edge. Three or four sutures are required for full eversion of the stoma (Figure 4A). The marking suture is cut or removed, and the proximal active stoma is everted. This maneuver is assisted by using the rounded, blunt end of the scalpel handle. The handle tip applies countertraction as the free mucosal edge is brought down to the skin with forceps or a similar grasping instrument (Figure 5). The cephalad bowel wall is then secured about its perimeter to the subcutaneous skin with interrupted fine absorbable sutures. Rods with “T” ends need not be secured. Others should be secured by placing a non-absorbable monofilament suture at each end of the rod (Figure 6).
The viability of the stoma is rechecked and the intra-abdominal portion of the loop is examined. The loop must come up without angulation or tension, since postoperative ileus may distend the abdomen. Finally, the ileal loop opening through the abdominal wall is reevaluated for snugness. An opening that allows passage of the loop plus one finger is recommended to minimize constriction or herniation.