Ostomy Care

The word ostium means “opening.” Thus the words ileostomy and colostomy refer to openings into the ileum and colon, respectively, which are the subjects of this chapter. Other ostomies include gastrostomies and jejunostomies, which usually are formed for the purpose of alimentation, and ileal loop urostomies, which are formed to replace the urinary bladder.

An ileostomy is usually the end result of a total proctocolectomy. A colostomy may be formed after a partial colon resection, typically for cancer, diverticulitis, or ischemic disease.

I. FORMATION OF OSTOMIES.

Most ileostomies and colostomies are formed by bringing the bowel out through an incision in the abdominal wall and suturing the mucosa to the skin. Some are “double-barrel,” meaning that the bowel leads both to and away from the opening. Two important modifications of ileostomies are available.

The Kock pouch, or continent ileostomy, is a pouch fashioned from ileum just proximal to the ostomy and functions as a reservoir for stool. The stoma is formed in the shape of a nipple, which is cannulated for drainage several times a day. Most patients with Kock pouches remain continent and do not require an ostomy bag.

B. Ileorectal pull-through.

The second modification is not actually an ileostomy but rather a form of anorectal anastomosis, called an ileorectal pull-through. The entire colon is removed except for the distal rectum. The distal rectum is stripped of mucosa, and the ileum is connected to the anus within the muscular sheath of the rectum, which includes the anal sphincter. To improve continence, a pouch can be formed from the distal ileum.

II. CONSEQUENCES AND COMPLICATIONS OF OSTOMIES.

Because the colon absorbs water and electrolytes in sufficient amounts to form a firm stool, patients with ileostomies can be expected to lose water and electrolytes more than healthy people do. The normal daily stool of a person whose bowel is intact weighs 100 to 200 g and contains 80% to 85% water. A normally functioning ileostomy discharges 500 to 1,000 g of stool per day, containing 90% to 95% water. Furthermore, whereas healthy people can reduce stool sodium losses to 1 to 2 mEq per day by conserving sodium in the colon, patients with ileostomies have obligatory daily sodium losses of 30 mEq or more.

If the terminal ileum has been removed in addition to the colon, bile salt and vitamin B₁₂ malabsorption may occur (see Chapter 31). The loss of bile salts may predispose to steatorrhea, which worsens the diarrhea.

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