Convex vs Flat Barrier Ring: How to Choose for Your Stoma

Choosing between a convex and a flat barrier ring comes down to one thing: how your stoma sits against your skin. Choose a convex barrier ring if your stoma sits flush with your skin, pulls inward, or sits in a dip or skin fold, because the curved shape gently presses the skin down and helps the stoma stick out. Choose a flat barrier ring if your stoma already protrudes and the skin around it is firm and even. Get the shape right and you stop the leaks and sore skin that come from output sneaking under the seal.

Here is how the two compare, when each one works best, and how to tell which your stoma needs. If you are new to barrier rings, our guide to what an ostomy barrier ring is covers the basics first.

In this article

• What is the difference between a convex and a flat barrier ring?
• When should you use a convex barrier ring?
• When is a flat barrier ring the better choice?
• Convex vs flat barrier ring at a glance
• Which should you choose?
• Frequently asked questions

What is the difference between a convex and a flat barrier ring?

A flat barrier ring sits level against your skin, while a convex ring curves outward so it presses gently into the skin around the stoma to push it up and out. A barrier ring itself is a soft, moldable seal that sits between your skin and your ostomy wafer (the adhesive part of your pouching system) and fills the small gaps and uneven spots around your stoma so output cannot creep underneath.

The flat version is the everyday workhorse. It builds up the seal on skin that is already even. The convex version does an extra job: its curved shape adds gentle pressure that coaxes a stubborn, flat, or sunken stoma to protrude a little more, which directs output up into the pouch instead of leaking sideways. Hollister builds both shapes into its ceramide-infused CeraRing line, ceramide being a natural skin component that helps protect the peristomal skin (the skin right around your stoma).

When should you use a convex barrier ring?

Use a convex barrier ring if your stoma is flush with or below the skin, protrudes less than about three quarters of an inch, or sits in a crease, dip, or soft spot on your abdomen. These are the situations where a flat seal struggles to hold and leaks keep coming back. According to Hollister, weight changes and post-surgery healing can also change stoma height over time and create a new need for convexity, so the ring that worked last year may not be the right one now.

Convexity comes in soft and firm. Soft convexity flexes as you move and tends to suit firmer abdomens, while firmer convexity gives more support and often suits softer abdomens. This is the one area worth confirming with your ostomy nurse, who can look at your stoma and tell you whether convexity will help and how much.

When is a flat barrier ring the better choice?

A flat barrier ring is the better choice when your stoma already protrudes and the skin around it is firm and even, because it adds a secure seal without pressing on skin that does not need it. Pushing convexity onto a stoma that sticks out well can be uncomfortable and is not needed. If a flat seal holds for your normal wear time without leaks, there is no reason to change shape.

Flat rings also give you room to fine-tune. A wide 4-inch ring covers more skin and gives a larger sealing surface, while a slim 2-inch ring keeps a lower, more discreet profile under clothes. If barrier paste stings your skin or you dislike the mess, a soft hydrocolloid ring is a sting-free alternative that does the same gap-filling job. We compare those two approaches in barrier ring vs ostomy paste.

Convex vs flat barrier ring at a glance

Here is the short version side by side. The right pick is the row that matches your stoma, not the more expensive or more advanced ring.

	Convex ring	Flat ring
Best for	A stoma that sits flush, pulls inward, or sits in a fold	A stoma that protrudes, with firm even skin
What it does	Curves in to press skin down and lift the stoma	Builds a level seal on even skin
Main reason to use	Stops leaks a flat seal cannot hold	Reliable seal without extra pressure
In our range	CeraRing Oval Convex, from $54.32	CeraRing Flat 4" and Slim 2", SoftFlex, from $30.00
Best to confirm with	Your ostomy nurse, who checks stoma height and skin	Your own wear time and leak history

Which should you choose?

Start by looking at your stoma in a mirror after a clean change: if it stands out past the skin and the area is smooth and firm, a flat ring is usually all you need; if it sits level, sinks below the skin, or hides in a crease, a convex ring is likely the fix. Repeated leaks on a flat ring, especially leaks that start near a dip or fold, are the clearest sign to try convexity.

Two cautions keep this safe. First, more convexity is not automatically better, so do not jump to a firm convex ring if a soft one or a flat one already holds. Second, convexity is the one feature worth checking with an ostomy care nurse before you commit, because the right amount depends on your stoma and the firmness of your abdomen. If leaks are your main problem, our guide to why an ostomy wafer keeps leaking walks through the other causes worth ruling out.

Frequently asked questions

Is a convex barrier ring better for leaks?

It is better for leaks caused by a flat, sunken, or unevenly seated stoma, because the curve presses the skin down and lifts the stoma so output goes into the pouch. If your stoma already protrudes, a flat ring usually seals just as well without the extra pressure.

Can I use a convex ring if my stoma sticks out?

Usually you do not need to. Convexity is designed to help a flush or retracted stoma protrude. On a stoma that already sticks out with firm, even skin, a flat ring is more comfortable and seals well.

How do I know if my stoma is flush or retracted?

Look at it in a mirror after a fresh change. A protruding stoma stands out past the skin, a flush stoma sits level with it, and a retracted stoma sits at or below the skin. If it sits level or lower, or hides in a fold, convexity may help. Your ostomy nurse can confirm.

What is the difference between soft and firm convexity?

Soft convexity flexes as you move and often suits firmer abdomens. Firm convexity gives more support and often suits softer abdomens. An ostomy nurse can tell you which is right for your body.

Are barrier rings FSA or HSA eligible?

Yes. Ostomy barrier rings, including the convex and flat CeraRing rings and SoftFlex, are eligible expenses under most FSA and HSA plans.

Can I use a barrier ring instead of paste?

Yes. A soft moldable ring like SoftFlex does the same gap-filling job as barrier paste, without the sting or mess that some people dislike. See our full comparison of barrier ring vs ostomy paste.

Sources: Hollister, How a Convex Skin Barrier May Help You Get the Right Fit; United Ostomy Associations of America, 4 Common Convex Ostomy Skin Barrier Myths. Convexity should be confirmed with your ostomy care nurse.