Loop Colostomy

A temporary loop colostomy is often created for patients who have an extra-peritoneal rectal injury after a transpelvic gunshot wound.   The purpose of these loop colostomies is to divert stool from the rectal wound in order to prevent a pelvic abscess.  Presacral drains are often placed to help drain the area around the colonic injury.  These drains are normally advanced (or pulled back) an inch a day starting on post operative day number 3.

It is important to create the ostomy site so that it will be visible to the patient.  In an obese patient with a pannus, the stoma should be located in the upper abdomen.  The stoma should also be away from the umbilicus, skin creases, scars and bony prominences. 

The site for the colostomy is prepared making a circular incision, 4-5 cm in diameter.  In an obese patient, a core of subcutaneous tissue can be removed along with the overlying skin down to the fascia to allow the ostomy to be easily brought to skin level.  If the patient is skinny, the overlying skin can be removed, and the subcutaneous tissue is dissected down to the fascia using cautery and army/navy retractors.  The fascia is incised with a crutiate incision and the muscle is cauterized to expose the posterior rectus sheath.  Before dissecting through the posterior rectus sheath, a large malleable should be placed in the abdomen under the posterior rectus sheath to protect the bowel.  You should be able to place two fingers through the ostomy opening.  The colon is then mobilized by dividing the peritoneum at the base of the mesentery.  If the colon needs to be mobilized further, the adjacent colonic flexure can be taken down.

Next, an opening is made in the mesentery next to the colon where you want to bring the colon out to the skin.  A penrose drain is then placed through the hole of the mesentery.  With gentle traction on the penrose through the opening and gentle manipulation from the intraperitoneal aspect of the colon, the loop of colon is delivered through the abdominal wall opening.  Once the colon is delivered without tension, the penrose is replaced by a bar or a shortened red rubber catheter.  This is called a bridge.  The bridge helps support the posterior wall of the colon and prevents the ostomy from retracting into the abdomen.  The bridge is secured in place by 2-0 nylon sutures.  The bridge is removed on post operative day 5.

The midline abdominal wound is then closed before maturation of the colostomy.  The loop of transverse colon is opened longitudinally along the taeniae coli.  The colostomy is then matured by suturing the full thickness of the bowel wall to the dermis of the skin with interrupted 3-0 vicryl sutures. 

from Fischer JE, et al: Mastery of Surgery, 5th Ed. 2007

Thanks to Dr. John Cull for this post.