A sigmoid colostomy is a surgically created opening in the lower left side of your abdomen where the end of the sigmoid colon (the last S-shaped section of your large intestine before the rectum) is brought through the skin surface. This opening, called a stoma, reroutes stool so it exits into an external pouch instead of passing through the rectum. It is the most common type of colostomy, and it produces output closest to normal stool in consistency because nearly the entire colon is still functioning upstream.
Where the Sigmoid Colon Sits and What It Does
The sigmoid colon is the final stretch of your large intestine. It connects the descending colon, which runs down the left side of your abdomen, to the rectum. Shaped like the letter S, it sits in the pelvis and has enough slack to shift position slightly, which is why surgeons can mobilize it to create a stoma on the abdominal wall.
By the time digested food reaches the sigmoid colon, most of the water and nutrients have already been absorbed. The sigmoid’s job is to extract whatever water, vitamins, and minerals remain so that stool becomes solid enough to store in the rectum until a bowel movement. This is why a sigmoid colostomy produces relatively firm, formed stool: the colon upstream has already done the heavy lifting of turning liquid waste into something solid.
How Stool Output Differs From Other Colostomies
Not all colostomies produce the same kind of output. The higher up on the colon the stoma is placed, the more liquid and acidic the stool will be, because less of the colon has had a chance to absorb water. An ascending colostomy (placed on the right side, near the start of the colon) produces liquid or semi-liquid output. A transverse colostomy (placed across the upper abdomen) produces loose, oatmeal-like stool that tends to be foul-smelling. A descending or sigmoid colostomy produces paste-like to fully formed stool that closely resembles what you’d pass normally through the rectum.
This difference matters for daily life. Because sigmoid colostomy output is firmer and less acidic, it is gentler on the surrounding skin and easier to manage with a standard pouching system. People with colostomies higher on the colon often deal with more frequent emptying and greater skin irritation.
Why a Sigmoid Colostomy Is Performed
Several conditions can damage or block the lower colon or rectum badly enough to require diverting stool above the problem area. The most common reasons include:
- Colorectal cancer: When a tumor in the sigmoid colon or rectum needs to be removed and a safe reconnection isn’t possible at the time of surgery.
- Perforated diverticulitis: Infected pouches in the sigmoid colon wall can rupture, spilling contents into the abdominal cavity. The standard emergency treatment, called a Hartmann procedure, removes the damaged segment, closes off the rectal stump, and creates an end colostomy from the remaining descending colon.
- Fecal incontinence: When the muscles controlling the rectum no longer function adequately, a sigmoid colostomy can provide a controlled way to manage waste.
- Complex anorectal conditions: Injuries, fistulas, or radiation damage to the rectum or anus may require fecal diversion while the area heals, or permanently if repair isn’t feasible.
Temporary vs. Permanent
A sigmoid colostomy can be either temporary or permanent, depending on the underlying condition and how well your body heals. Temporary stomas are commonly created during emergency surgery for perforated diverticulitis or to protect a new surgical connection further down the colon while it heals. Once the acute problem resolves and imaging confirms the downstream connection is intact, the stoma can be reversed and normal bowel continuity restored.
The reality, though, is that reversal doesn’t always happen. Only about half of patients who undergo a Hartmann procedure ever have it reversed, partly because the reversal surgery itself carries a complication rate above 50%. Across all types of temporary stomas, somewhere between 6% and 32% of patients end up keeping them permanently. Risk factors that make reversal less likely include advanced age, cancer that has spread, complications at the original surgical connection, and the need for chemotherapy.
When reversal is planned, surgeons typically wait at least three to six months to let internal inflammation settle and scar tissue soften before operating again.
What the Stoma Looks Like
The stoma itself is a small, round piece of intestinal lining that protrudes slightly from the skin surface, usually about half a centimeter to one centimeter. It’s pink or red, moist, and has no nerve endings, so touching it doesn’t hurt. It’s placed in the lower left abdomen, a few inches below where a descending colostomy would sit, positioned through the abdominal muscle to help anchor it in place and reduce the risk of hernia.
A flat adhesive pouch fits over the stoma to collect output. Because sigmoid colostomy stool is formed, many people empty or change the pouch once or twice a day on a fairly predictable schedule.
Colostomy Irrigation
One advantage specific to sigmoid and descending colostomies is the option to irrigate. Irrigation involves flushing warm water through the stoma into the colon, which triggers a controlled bowel movement on your schedule. Done at the same time each day, it can train the bowel to empty predictably and keep you free of any output for 24 to 48 hours between irrigations. Some people who irrigate successfully can wear just a small stoma cap instead of a full pouch during the day.
The process takes about an hour to an hour and a half. You start with a small volume of water (around 250 mL) on the first day and gradually increase over several days to 750 or 1,000 mL, depending on your results. The water needs to be warm, never hot or cold, and the irrigation bag hangs at shoulder height to control flow speed. Cramping during irrigation usually means the water is flowing too fast or the bag is hung too high. You should not irrigate if you have diarrhea, a prolapsed stoma, or a hernia around the stoma, and it’s generally not recommended during chemotherapy or radiation.
Common Complications
Stoma-related complications are common enough that being aware of them helps you catch problems early. A systematic review of clinical trials found complication rates ranging widely, but two issues stand out for end colostomies like a sigmoid colostomy.
Parastomal hernia is by far the most frequent long-term problem, occurring in a median of about 59% of end colostomy patients over time. This happens when abdominal tissue pushes through the muscle around the stoma, creating a visible bulge. Many parastomal hernias are manageable with a support belt, but some require surgical repair.
Peristomal skin irritation is the other common issue, though it affects end colostomy patients at lower rates (around 3.6%) than those with loop colostomies or ileostomies. The firmer, less acidic output of a sigmoid colostomy is the reason. Stoma prolapse, where the bowel telescopes outward beyond its normal length, occurs in roughly 4% of end colostomy cases.
Diet and Daily Life
Most people with a sigmoid colostomy can eat a wide variety of foods, but certain items are worth approaching carefully. Foods that commonly cause gas include beans, carbonated drinks, and sweetened beverages. Nuts, corn, coconut, dried fruit, and mushrooms can physically block the stoma if not chewed thoroughly, because these fibrous foods don’t break down easily. Alcohol (especially beer), chocolate, spicy foods, and egg yolks tend to increase odor or cause digestive discomfort for some people.
Staying well hydrated matters, since the colon’s water absorption is partially interrupted. Beyond dietary adjustments, most people return to work, exercise, travel, and social activities. The formed output and predictable schedule of a sigmoid colostomy, especially for those who irrigate, make it one of the easier stoma types to integrate into daily routines.