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 ...