A stoma is a surgically created opening in the abdomen where a section of intestine is brought through the abdominal wall to the skin’s surface, allowing waste to exit the body without passing through the rectum. Instead of the usual route, digested food or urine is rerouted to this opening and collected in an external pouch worn against the body.
What a Stoma Actually Is
The word “stoma” refers to the visible opening itself. It’s a roundish piece of intestinal tissue, typically one to two inches wide, that sits on the surface of the abdomen. It looks pink or red and has a moist appearance similar to the inside of your mouth. Some stomas lie flat against the skin, while others protrude slightly. Right after surgery it tends to look swollen, but it gradually shrinks over the following weeks.
One important detail: a stoma has no nerve endings. You can’t feel it the way you feel your skin. Once the surgical site heals, you won’t feel sensation in the stoma tissue itself, though the surrounding skin remains sensitive.
How Waste Moves Through
Your intestines move their contents forward using peristalsis, the rhythmic muscle contractions that push food along without any conscious effort on your part. That process doesn’t change after stoma surgery. The intestine still contracts and pushes waste forward, but instead of traveling all the way to the rectum, waste exits at the point where the intestine meets the abdominal wall.
The key difference from normal digestion is the absence of a sphincter. Your rectum has muscles you can consciously tighten and relax, giving you control over when you have a bowel movement. A stoma has no such muscle. Waste comes out whenever peristalsis pushes it to that point, which means output is continuous or intermittent depending on the type of stoma and what you’ve eaten. You have no voluntary control over when gas or stool exits.
Types of Stomas and What They Produce
The type of stoma you have depends on which part of the digestive (or urinary) tract is rerouted. Each type produces different output because of where it sits in the digestive process.
- Colostomy: A piece of the colon (large intestine) is brought to the surface. Because the large intestine absorbs water, colostomy output is generally more formed, especially when the stoma is made from the descending or sigmoid colon, which are the last sections before the rectum. Solid stool starts forming in these segments, so the output can resemble a normal bowel movement.
- Ileostomy: The ileum, the lowest part of the small intestine, is brought to the surface. At this point, the large intestine has been bypassed entirely, so the body hasn’t had a chance to absorb as much water. Ileostomy output is looser and more liquid, typically ranging from 500 milliliters to one liter per day. Anything above one liter in 24 hours is considered high output and can lead to dehydration.
- Urostomy: This type diverts urine rather than stool. A small segment of intestine is used to create a channel from the ureters to the skin surface, so urine drains continuously into a pouch.
How the Pouching System Works
Since waste exits unpredictably, a pouching system is worn over the stoma at all times. The system has two main components: a skin barrier (also called a wafer or baseplate) and the pouch itself.
The skin barrier is an adhesive disc that sticks to the skin around the stoma. It’s made from a combination of moisture-absorbing compounds and an adhesive framework that work together to create a seal. As the inner edge absorbs small amounts of moisture, it swells slightly against the stoma, tightening the seal and preventing waste from leaking onto the surrounding skin. This matters because digestive output, particularly from an ileostomy, contains enzymes that can quickly irritate and break down unprotected skin.
The pouch attaches to the barrier and collects the output. Some systems are one piece, where the barrier and pouch are fused together. Others are two-piece systems, where the pouch clicks or snaps onto the barrier, allowing you to change the pouch without removing the adhesive from your skin each time. Most pouches are emptied several times a day through a clip or closure at the bottom, then changed entirely every few days.
How Gas Is Managed
Gas is produced by the same digestive processes as before surgery, but now it exits through the stoma into the pouch. Without a filter, gas would inflate the pouch, causing it to balloon visibly under clothing.
Most modern pouches include a small charcoal filter built into the pouch wall or added as an adhesive sticker. The filter uses activated charcoal to neutralize odors and a water-repelling membrane that allows gas to pass through slowly while keeping stool and liquid inside. This lets gas release gradually throughout the day without the pouch ballooning or producing noticeable smell.
How Food Affects Stoma Output
What you eat directly affects the consistency, volume, and odor of stoma output, particularly with an ileostomy. Bland, low-fiber foods tend to produce thicker, more manageable output. Fatty foods can cause discomfort. Carbonated drinks often increase gas. Fish and nut butters can create stronger odor when the pouch is opened.
Blockages are a real concern, especially with ileostomies. Because the stoma opening is narrower than the normal intestinal path, certain fibrous or hard-to-digest foods can get stuck. Corn is a common culprit, along with other high-fiber foods that don’t break down easily. A blockage, also called a bowel obstruction, can be partial or complete. The warning signs are no gas or output from the stoma for six hours combined with cramping, pain, or nausea. This requires prompt medical attention.
Most people learn through experience which foods work well and which cause problems. In the early weeks after surgery, a low-residue diet (low in tough fiber) is typical, with new foods reintroduced gradually in small amounts.
Daily Life With a Stoma
Because stoma output is involuntary, managing it becomes part of daily routine. Ileostomy pouches need emptying more frequently, often five to eight times a day, because the output is more liquid and higher in volume. Colostomy pouches, especially from the descending or sigmoid colon, may need emptying less often since the output is firmer and more predictable.
Some people with a descending or sigmoid colostomy use a technique called irrigation, which involves flushing water into the stoma to stimulate the colon to empty on a schedule. This can allow some colostomy users to go hours without wearing a full pouch, using just a small cap over the stoma instead. Irrigation doesn’t work for ileostomies because the output is too liquid and continuous.
Staying hydrated is especially important with an ileostomy. Because the large intestine, which normally reclaims a significant amount of water, has been bypassed, fluid and electrolyte losses are higher. Drinking more water and monitoring for signs of dehydration (dark urine, dizziness, fatigue) becomes a routine part of self-care.