Loop Ileostomy

A distal loop ileostomy is most commonly used for temporary diversion of the gastrointestinal contents to protect a colonic anastomosis. When it is constructed with a dominant proximal limb, this ostomy provides nearly complete diversion of succus. The loop ileostomy has replaced the traditional right transverse colon loop colostomy in many circumstances, as this loop is easier to construct and close. Additionally, the loop ileostomy has proven to be no more difficult for the patient to manage than a proximal colostomy. A loop ileostomy, however, does not decompress the colon when the ileocecal valve is intact. In those patients who require acute colon decompression, a loop colostomy will allow both colon decompression and colon preparation for a staged procedure.

Most patients undergoing emergency or complex operations on the colon are counseled by the surgeon about the potential need for an ostomy. If available, an enterostomal therapist should visit the patient prior to surgery. The potential ostomy site should be marked with indelible ink (Figure 1). An ostomy is best placed near the lateral edge of the rectus muscle and sheath. It may be placed either above or below the umbilicus. The position chosen must take into consideration the span of the ostomy gasket, such that it has a smooth, wide surface for adherence. The costal margin, indentation of the umbilicus, uneven scars, and skin folds will not allow secure placement of the ostomy gasket. In general, the belt line should be avoided, and the patient should both stand and sit with an appliance in place during this marking. The patient should be reassured about his or her ongoing care with the enterostomal therapist. Reading material and samples are often provided. If an enterostomal therapist is unavailable, the surgeon should make every effort to educate the patient using these written and pictorial aids.

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.

A sterile ostomy appliance is placed after closure of the main abdominal incision.

The ostomy is observed for viability and its output is measured. As the patient resumes oral intake, the volume of succus will increase. Careful monitoring of fluid and electrolyte balance is required, especially if an overly large (≥2 L/day) output occurs. Dietary regulation may require supplementation with antimotility drugs. The enterostomal therapist should teach the patient how to care for the stoma. Many patients will benefit from a home visit by the nurse or therapist, wherein both patient and caregiver become proficient in changing the appliance. The plastic rod is removed about 14 days after surgery. The timing for closure of this temporary diverting loop ileostomy is determined by the healing of the colon anastomosis being protected.