Ostomy and Convexity

What is convexity?

It refers to the outward shape of the faceplate, almost like the top of a bell, intended to reach inside the peristomal skin for maximum seal around the stoma.

Why Convexity in Ostomy Appliances?

Convexity in Ostomy Appliances exists to provide optimal peristomal seal. A stoma can have uneven shape, unusual size, and irregularities around the peristomal skin area which render non-convex ostomy systems ineffective. A convex ostomy bag system curves outwards. With that profile, it can press the peristomal skin to protrude the stoma enough for the ostomy bag to attach securely and firmly.

The ideal convex system should deliver the following:

  • Avoid ostomy leaking.
  • Adapt naturally to the peristomal skin contour while sustaining the movements and tensions caused during normal wear.
  • Support a healthy peristomal skin area.
  • Feel comfortable and secured.
  • Increase ostomy bag wear.

When are Convex Bag Systems Recommended?

Convex ostomy bag systems have been consistently worn postoperatively for up to two months from discharge or after the stoma reaches its normal size. Nowadays, convexity is being used more often in the presence of the following situations:

When are Convex Bag Systems Not-Recommended?

It is important to consult with your ostomy professional before adopting this type of appliance. If you start using one and develop rashes, bleeding, pain, or itching, seek professional advice. These could be symptoms of conditions that require immediate treatment, and if present, a convex bag system should not be used. The main such conditions are the following:

Attaining convexity:

There are numerous ways to attain convexity. Most manufacturers have convex barriers to fit two-piece pouch systems and convex one-piece ostomy pouch alternatives. Additionally, there are pre-cut and cut-to-fit options for regular and irregular stoma shapes respectively. Convex alternatives vary in depth: shallow, moderate, and deep, as well as in texture: firm and soft. There are implications to selecting one versus another. Your ostomy nurse should help determine the right choice through an evaluation of your situation. Achieving convexity at first is not that straightforward. Your nurse might need to adjust sizes with convex inserts, barrier rings, convex wafers, strips or pastes. Whichever combination is determined, it will need close monitoring to ensure that the objectives from convexity are met. Once you become familiar with the process, you may try certain variants on your own.

What do manufacturers offer in terms of convexity?


Makes the Premier One-Piece and the New Image Two-Piece ostomy bag systems. The first one comes with convexity included, and the second uses the New Image skin barrier . Further adjustments can be managed with Adapt Convex Barrier Rings. These come in round and oval shapes, and can be placed one of top of the other to adjust to your ostomy bag system. It is used to reach deep or flexible convexity.


Has the Active Life One-Piece Convex line that includes the ostomy bag and the convex barrier into one unit. It counts also with the Durahesive Skin Barrier which can be moldable to the skin’s contour.


SenSura one and two piece ostomy pouches come with convex faceplates in pre-cut or cut-to-fit options.


Microskin from Cymed is not a convex accessory per se, but its properties to adjust to almost any peristomal skin contour make it a suitable choice.


A parastomal ostomy belt provides extra firmness and pressure for a better convex fit. Nu-hope carries what is probably the best and most extensive selection of ostomy belts.

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