A stoma is a surgically created opening in the abdomen that allows waste to leave the body when the normal route is blocked, damaged, or too diseased to function. Around 100,000 ostomy surgeries are performed each year in the United States, and between 725,000 and 1 million Americans are currently living with one. The causes range from cancer and inflammatory bowel disease to traumatic injuries and birth defects, depending on whether the stoma diverts the colon, the small intestine, or the urinary tract.
Colorectal Cancer: The Most Common Cause in Adults
Colorectal cancer is the single most common reason adults receive a stoma. When a tumor sits low in the rectum, surgeons sometimes need to remove the rectum entirely, leaving no way to reconnect the bowel. In that case, a permanent colostomy reroutes the colon to an opening on the abdominal wall. Even when the bowel can be reconnected after tumor removal, surgeons often create a temporary stoma upstream to protect the healing junction. Once the connection has healed (typically over several weeks to months), the temporary stoma is reversed and normal bowel function resumes.
Left-sided colon cancers that cause a blockage can also require an emergency stoma. The goal in these situations is to decompress the backed-up bowel quickly, relieve the obstruction, and stabilize the patient before any further surgery.
Inflammatory Bowel Disease
Crohn’s disease and ulcerative colitis are the two forms of inflammatory bowel disease that most often lead to stoma surgery. In ulcerative colitis, the inflammation is limited to the colon and rectum. When medications fail to control severe flares, or when precancerous changes develop, the entire colon and rectum may be removed. That procedure typically results in an ileostomy, where the end of the small intestine is brought through the abdominal wall.
Crohn’s disease can affect any part of the digestive tract and tends to recur after surgery. A stoma may be needed when the disease causes deep fistulas (abnormal tunnels between the bowel and skin or other organs), severe infection around the anus, or repeated bowel obstructions from scar tissue. Because Crohn’s can come back in the remaining intestine, some patients who initially receive a temporary ileostomy end up needing further surgery later.
Diverticulitis and Bowel Perforation
Diverticulitis occurs when small pouches in the colon wall become inflamed or infected. Most cases resolve with antibiotics, but a severe episode can cause the colon to perforate, spilling stool into the abdominal cavity. This is a life-threatening emergency. Surgeons remove the damaged section of colon and, because the surrounding tissue is too inflamed for a safe reconnection, bring the healthy end out as a colostomy. This procedure, known as Hartmann’s operation, is one of the most frequently performed emergency bowel surgeries. The stoma is often reversed months later once the infection has fully cleared.
Traumatic Injury
Penetrating injuries to the abdomen, particularly gunshot and stab wounds, can tear through the colon or rectum. When the damage is extensive or the wound is heavily contaminated, repairing the bowel directly carries a high risk of the repair breaking down. In these cases, surgeons divert the stool stream by creating a stoma, giving the injured tissue time to heal without exposure to bacteria-laden stool. High-velocity military wounds, which cause massive tissue destruction, almost always require a colostomy or ileostomy rather than a primary repair.
Rectal injuries in particular are more likely to be diverted than repaired, because the rectum sits deep in the pelvis and is difficult to access and stitch securely.
Bowel Obstruction and Volvulus
A bowel obstruction blocks food and waste from moving through the intestine. When the blockage can’t be relieved with less invasive methods, a stoma may be the fastest way to decompress the bowel and prevent it from rupturing. One specific cause, sigmoid volvulus (a twisting of the lower colon that cuts off blood supply), is a leading reason for emergency colostomy in many parts of the world. If the twisted segment has already lost blood flow and died, it must be removed, and a stoma is created from the remaining healthy colon.
Bladder Cancer and Urinary Conditions
Not all stomas involve the bowel. A urostomy redirects urine through the abdominal wall when the bladder has been removed or can no longer function. Bladder cancer requiring full bladder removal is the most common reason. Other causes include bladder damage from radiation therapy, severe urinary incontinence that hasn’t responded to other treatments, spinal cord injuries that prevent the bladder from emptying, and congenital conditions like spina bifida.
In a urostomy, the surgeon uses a short segment of small intestine as a conduit. The ureters (tubes from the kidneys) are connected to this segment, and its other end is brought to the skin surface. Urine drains continuously into an external pouch.
Congenital Conditions in Children
In newborns and infants, the two most common reasons for stoma surgery are Hirschsprung’s disease and anorectal malformations (sometimes called imperforate anus). Hirschsprung’s disease is a condition where nerve cells are missing from a section of the bowel, preventing it from pushing stool forward. The affected segment must be removed, and a temporary stoma is often placed to allow the baby to grow before a final reconstructive operation.
Anorectal malformations are birth defects where the opening of the anus is absent, misplaced, or abnormally narrow. A colostomy is created shortly after birth to divert stool while surgeons plan and carry out the repair, which usually happens within the first year of life. Other less common pediatric causes include necrotizing enterocolitis (a serious intestinal infection in premature infants), colon atresia, and meconium ileus.
Surgical Complications
Sometimes a stoma becomes necessary not because of the original disease, but because of a complication during or after surgery. The most common scenario is an anastomotic leak, where a newly created bowel connection fails to heal and begins leaking intestinal contents into the abdominal cavity. This triggers a serious infection that requires emergency surgery, and the safest option is usually to take down the leaking connection and create a stoma.
Dense scar tissue from prior surgeries can also make bowel reconnection impossible. In some reversal operations, surgeons find the tissue so scarred and fixed in place that they cannot safely complete the procedure and must form a new stoma instead.
Temporary vs. Permanent Stomas
Whether a stoma is temporary or permanent depends on how much bowel or rectum remains, whether the underlying disease is curable, and whether a safe reconnection is technically possible. Temporary stomas are common after rectal cancer surgery, emergency procedures for diverticulitis, and pediatric reconstructive operations. They are typically reversed once healing is confirmed, often within 3 to 12 months.
Permanent stomas are more likely when the entire rectum and anal sphincter have been removed (as in some low rectal cancers), when inflammatory bowel disease has destroyed too much of the colon to allow reconnection, or when a patient’s overall health makes further surgery too risky. For bladder cancer requiring full bladder removal, the urostomy is almost always permanent.