What Is an Ostomy Bag? A Plain-Language Guide

Last verified: October 6, 2026. An ostomy bag is a lightweight, sealed pouch worn on the outside of the abdomen to collect body waste that leaves through a surgically created opening called a stoma. It is also called an ostomy pouch, an appliance, or, depending on the type of surgery, a colostomy bag, an ileostomy bag, or a urostomy bag. This guide explains what an ostomy bag is, the main systems and types, who uses one, how it differs from other collection devices, and what supply teams should know.

This page is general information, not clinical or safety training. Always follow your institution’s procedures and the manufacturer’s instructions for any device.

What Is an Ostomy Bag?

An ostomy is an operation that brings part of the intestine or urinary tract to the surface of the abdomen to create a stoma, which is a small, moist, pink or red opening with no sphincter muscle. Because the person cannot control when waste leaves through the stoma, an external pouch is worn over it to collect the output. The ostomy bag attaches to the skin with an adhesive, and it is emptied or replaced as needed.

The bag is only one part of what is generally called an ostomy appliance. The system typically includes a skin barrier, sometimes called a wafer or flange, that sticks to the skin around the stoma and protects it from the output, and the pouch itself, which either attaches to the barrier or is built into it. A good seal between the barrier and the skin is central to how well the system works.

Why Ostomy Bags Exist

Surgeons create ostomies for many reasons, including bowel disease, cancer, injury, and bladder problems, and some are temporary while others are permanent. After the operation, the body’s normal route for waste no longer works in the same way, and the person needs a reliable, discreet way to manage it. An ostomy bag does that. It contains waste and odor, protects the skin, and allows people to return to work, school, travel, and daily life. The equipment is a major part of how someone adapts to living with a stoma.

Who Uses an Ostomy Bag

People of all ages use ostomy bags, from infants to older adults. They are worn at home, in hospitals, and in long-term care. Specialist nurses, often called ostomy or wound, ostomy, and continence nurses, usually teach people how to fit and change their equipment and help choose products. The selection of a system is individual, depending on the stoma’s type, shape, and position, the person’s skin, body contour, dexterity, and lifestyle. A general guide cannot make those choices.

Types of Ostomies and What They Collect

• Colostomy: the stoma is formed from part of the large intestine (colon). Output tends to be more formed the further along the colon the stoma is.
• Ileostomy: the stoma is formed from the end of the small intestine (ileum). Output is generally looser and more frequent, and contains digestive enzymes that can irritate skin, so skin protection is a prominent concern.
• Urostomy: a stoma that diverts urine, usually created after the bladder is removed or bypassed. The pouch for a urostomy has a drainable spout and often a valve designed to connect to a night drainage bag.

Types of Ostomy Bags and Systems

One-Piece Systems

In a one-piece system the pouch and the skin barrier are a single unit. The whole unit is stuck on and removed together. These are generally low-profile, flexible, and simple to apply, and many people like them for discretion.

Two-Piece Systems

A two-piece system has a separate barrier and pouch that click or stick together. The barrier can stay on the skin for several days, and the pouch can be changed or swapped without removing the adhesive each time, which may reduce skin irritation. This also lets the wearer change pouch style, for example for bathing or sleeping.

Drainable vs. Closed Pouches

A drainable pouch has an opening at the bottom that closes with a clip or integrated closure so the user can empty it without removing the pouch. This is common with ileostomies and urostomies, where output is frequent or liquid. A closed pouch has no opening and is discarded when full, which can suit people with more predictable, formed output.

Barrier Shapes

Skin barriers come flat, convex (curved outward to help with stomas that sit flush with or below the skin), and in pre-cut or cut-to-fit versions. Moldable barriers are also available. Fit matters because even a small gap can let output reach the skin.

Accessories

Other items often used with ostomy bags include barrier paste or rings to seal gaps, adhesive removers, protective skin wipes, belts or support bands, odor-control products, and pouch covers. Choice depends on the person and is usually guided by their nurse or care team.

How an Ostomy Bag Differs from Related Devices

• Ostomy bag vs. urinary drainage bag. A urinary drainage bag collects urine from a catheter, tube, or device inside the body. An ostomy bag sits directly over a stoma and sticks to the skin. A urostomy pouch is a kind of ostomy bag that collects urine from a stoma; for the catheter-connected version, see our guide to the Foley catheter.
• Ostomy bag vs. bedpan or toilet-based devices. A bedpan is a container for people who cannot get to a toilet. It collects waste passed in the ordinary way, not output from a surgically created stoma.
• Ostomy bag vs. suction or drainage canisters. A suction canister collects fluid drawn out by suction equipment, rather than output that flows into a bag by gravity from a stoma.
• Ostomy bag vs. surgical drain. A surgical drain removes fluid from a wound or body space after surgery, typically into a small bulb or bag, and is generally temporary. An ostomy is a deliberate, ongoing diversion of the digestive or urinary tract.

Living with an Ostomy Bag: The Practical Side

Much of the day-to-day experience of an ostomy is about managing the interface between skin and equipment. The skin around the stoma is exposed to moisture and, in some cases, digestive enzymes, so protecting it is a central concern. Common issues that people and nurses work on include leaks under the barrier, skin redness or soreness, pouch ballooning from gas, and keeping the pouch discreet under clothing. Many of these are addressed by adjusting the fit or choosing a different barrier shape, adding sealing accessories, or revising the routine, which is why follow-up with a specialist nurse is often built into care. Patient support organizations also provide peer experience and practical tips, which complement but do not replace clinical advice.

For facilities, the practical lesson is that ostomy care is a skills-based service as well as a supply category. Having access to staff trained to fit and teach, and a stock range wide enough to match different stomas, tends to matter more than the price of any single pouch.

Practical Relevance for Research Administration and Procurement

Ostomy supplies are a good example of a product category where small differences matter and demand is steady, which has consequences for people who buy and budget for them.

First, there is no universal product. Stoma size, shape, and position, skin condition, and personal preference all affect which barrier and pouch work. Facilities usually keep a range of sizes and styles, and it is common for individual users to be matched to a specific product by a nurse. Substituting another brand without checking the fit can cause leaks and skin damage.

Second, usage is recurring and predictable. Pouches and barriers are changed on a regular schedule, and the number of items per person per month is fairly stable, which makes forecasting simple for long-term programs but makes supply interruptions costly for patients.

Third, compatibility between components is important. In two-piece systems, the barrier and pouch must match in coupling size and style, and accessories need to fit with them, so catalogs and reorders should specify exact product codes and sizes. See our long-term acute care hospital supply checklist for an example of how this kind of supply is grouped in a facility’s planning.

Fourth, reimbursement and coverage rules differ between payers and countries. Many programs cover ostomy supplies as a category of medical supply with documentation and quantity limits, and the details change over time. Research programs that follow people with ostomies may also need to record the device type consistently.

Frequently Asked Questions

What is an ostomy bag used for?

It collects waste that leaves the body through a surgically created opening, called a stoma, in the abdomen. This could be stool or urine depending on the type of ostomy.

Is an ostomy bag the same as a colostomy bag?

A colostomy bag is one kind of ostomy bag, used with a stoma formed from the large intestine. Ostomy bag is the broader term and also includes ileostomy and urostomy pouches.

What is the difference between a one-piece and a two-piece system?

A one-piece system has the pouch and skin barrier joined together, while a two-piece system has a separate barrier and pouch that connect. Which is better is a matter of individual fit and preference.

Is an ostomy permanent?

Some ostomies are temporary and may later be reversed, while others are permanent. That depends on the condition and the surgical plan decided by the care team.

Can people with an ostomy bag live normally?

Many people return to work, travel, exercise, and other activities with an ostomy. Specialist nurses and support organizations can help individuals with advice that fits their situation.

Are ostomy bags disposable?

Most ostomy pouches are single-use and are disposed of after being removed, following the manufacturer’s instructions and local waste rules. Some products are designed to be emptied several times before being replaced.

How often is an ostomy bag changed?

It depends on the type of system, the output, and the person’s skin. Change schedules are taught by ostomy nurses and set out in the manufacturer’s instructions rather than by a general rule.