What Is a Stoma?

A stoma is a surgically created opening on the surface of the abdomen that allows either digestive waste or urine to leave the body by a route other than the usual anatomical channels. The word comes from the Greek stoma, meaning mouth or opening. Rather than waste passing through the rectum and anus, or urine through the urethra in the normal way, it exits through the stoma and collects in a close-fitting, odour-resistant pouch worn against the skin.

Stomas are formed during operations carried out for a wide range of conditions, including colorectal cancer, bladder cancer, inflammatory bowel disease (IBD), diverticulitis, bowel obstruction, traumatic injury, and certain congenital abnormalities. They may be temporary — allowing part of the gastrointestinal or urinary tract time to heal — or permanent, when the affected segment has been surgically removed.

The Three Main Types of Stoma

Colostomy

A colostomy is formed from a section of the large bowel (colon). Part of the colon is brought through the abdominal wall and folded back on itself to create a spout-like opening. Output from a colostomy is typically semi-formed to formed stool, depending on how far along the colon the stoma is sited.

• Sigmoid colostomy: The most common type, formed from the lower end of the colon. Output is usually firm and close to normal stool consistency, and some people manage with irrigation rather than a permanent pouch.
• Transverse colostomy: Sited higher in the abdomen; output tends to be softer and more frequent.
• Ascending colostomy: Rare; output is more liquid, similar to ileostomy output.

Colostomies are most frequently created following surgery for colorectal cancer, diverticular disease, or bowel obstruction.

Ileostomy

An ileostomy is formed from the ileum, the final section of the small intestine. Because it bypasses the colon entirely, the output is liquid to porridge-like in consistency and considerably higher in volume than colostomy output. It is also more enzymatically active, meaning it can irritate the peristomal skin if leakage occurs. People with an ileostomy typically empty their pouch four to eight times per day and need to be vigilant about maintaining adequate fluid and electrolyte intake.

Ileostomies are most commonly created as part of surgical treatment for ulcerative colitis, Crohn’s disease, familial adenomatous polyposis (FAP), or colorectal cancer requiring removal of the entire colon.

Urostomy (Ileal Conduit)

A urostomy diverts urine when the bladder has been removed (cystectomy) or can no longer function adequately. The most common form is the ileal conduit, in which a short segment of ileum is isolated from the digestive tract and used as a channel: the ureters are attached to one end and the other end is brought out through the abdominal wall as the stoma. Urine drains continuously into a urostomy pouch. Urostomy pouches are fitted with a non-return valve and a drainage tap to prevent backflow and allow easy emptying.

Urostomies are performed most often following bladder cancer surgery, but also for bladder dysfunction caused by spinal injury or other neurological conditions.

How a Stoma Looks and Functions

A healthy stoma is moist, pink to red in colour, and slightly raised above the skin surface — much like the inside lining of the cheek. It has no nerve endings capable of registering pain, so touching it is painless. In the days immediately following surgery the stoma will appear swollen; this oedema gradually reduces over six to eight weeks, which is why the definitive pouch fitting is usually delayed until the stoma has settled to its permanent size.

Output begins within 24–72 hours after surgery. Nurses will monitor colour, output type, and volume closely in the early postoperative period, as changes can signal complications such as ischaemia, obstruction, or high-output state.

The Peristomal Skin

The skin surrounding the stoma — called peristomal skin — is one of the most clinically important areas in ostomy management. Healthy peristomal skin should look identical to skin elsewhere on the abdomen. Problems such as erythema, maceration, erosion, and contact dermatitis are common but largely preventable with correct pouch sizing, appropriate skin barrier products, and routine review.

Any persistent change in peristomal skin condition, including redness, bleeding, rash, or pain, should be assessed by a stoma care nurse promptly.

Why Stomas Are Created

The decision to form a stoma is never taken lightly and is usually made because one of three clinical situations applies:

1. The bowel or bladder must be rested — for example, following complex rectal surgery, to protect a newly formed join (anastomosis) while it heals.
2. The bowel or bladder has been removed — most commonly in cancer surgery, or in IBD when medical and other surgical options have been exhausted.
3. Normal function is impossible — as a result of injury, congenital abnormality, or severe dysfunction.

Life With a Stoma

Adjusting to life with a stoma involves both practical and psychological adaptation. In the short term, learning to manage the pouching system, understanding dietary influences on output, and regaining physical confidence are the main challenges. Over time, most people develop efficient, discreet routines.

Diet, exercise, travel, swimming, sexual activity, and pregnancy are all compatible with stoma life, though each requires some individual adjustment. Support from a stoma care nurse, ostomy patient associations, and peer support networks is associated with significantly better outcomes and quality of life.

The Bottom Line

A stoma is a surgically created abdominal opening — forming a colostomy, ileostomy, or urostomy — that redirects digestive waste or urine when the normal route is unavailable or unsafe. Stomas are more common than is often appreciated, and the great majority of people who live with one lead full, active lives. Understanding what a stoma is, why it is formed, and how it functions is the first step toward confident self-management.

Always consult your stoma care nurse or specialist clinician for personalised advice about your own stoma, as individual anatomy, underlying diagnosis, and pouching needs vary considerably from person to person.