UK Stoma Appliance Fitting · Interactive Selector + Printable Clinic Sheet

Flat vs. Convex Stoma Flange & Baseplate Selector UK (+ NHS Nurse Fitting Sheet)

Understand when NHS stoma care nurses recommend a flat baseplate versus soft or firm convexity for flush, retracted, or creased stomas—and print a 1-page observation sheet for your stoma clinic review.

Written by María G. · hola@siilostomy.com · Last updated: 14 November 20269 min read

Checking your tummy profile sitting upright as well as standing helps your NHS stoma nurse spot creases straight away.

Quick answer

ASCN UK clinical principle: A well-spouted stoma (>15–20 mm above skin level) on a smooth tummy works best with a flat baseplate (flange). If your stoma sits flush with the skin (0–4 mm), retracts below skin level, or tucks into a tummy crease when seated, a convex pouch (soft/light or firm) gently curves around the stoma to stop output tracking underneath. Important: always have an NHS stoma care nurse assess you in person before ordering convex bags on FP10 prescription.

>15–20 mmspouted stoma height ideal for flat flanges
0–4 mm flushprofile where Soft Convex is often trialled
Sit + standcheck tummy folds in both positions
ASCN UK rulenurse review required before starting convexity

Check clinical guidance by stoma spout height & tummy contour

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UK Stoma Appliance Fitting · Interactive Selector + Printable Clinic Sheet

Stoma spout height & opening position when sitting

Tummy firmness & bag output type

Educational summary for your NHS Stoma Care Nurse

Ideal match for a FLAT BASEPLATE: when your stoma spouts 15–20 mm cleanly into the bag, a well-cut flat flange (+2 mm aperture) gives gentle, pressure-free security.

On a firmer tummy, very gentle/flexible soft convexity provides plenty of support without causing pressure rings.

Comparing flat baseplates, soft convex, firm convex & mouldable seals

Before suspecting you need convexity, check your flange hole size with our UK 1:1 stoma measuring & flange aperture calculator—an oversized hole from post-op shrinkage is the single commonest cause of sore skin.

Comparing flat baseplates, soft convex, firm convex & mouldable seals
Appliance / Accessory	Typical NHS Stoma Clinic Use	Skin Safety Principle
Flat Baseplate (1- or 2-Piece)	Well-spouted stoma (>15–20 mm) on an even tummy	Standard first choice: zero peripheral pressure around the stoma.
Soft / Light Convex Pouch	Flush stoma, shallow folds, or firmer tummy wall	Flexible plateau moves comfortably; check skin at every bag change.
Moderate / Deep Firm Convex	Retracted stoma or deep fold in softer abdominal tissue	Initiated by an NHS stoma care nurse with a 1–2 week skin check.
Alcohol-Free Mouldable Seal / Ring	Filling slight dips right round the stoma root	Sting-free seal; avoid stacking thick seals under deep convexity unless advised.

Four helpful checks before ringing your stoma clinic for samples

Examine your tummy sitting in your usual chair
Creases often vanish when lying flat on a clinic couch—check how your tummy folds while sitting upright.
Snap a photo of the back of a used baseplate
Showing your stoma nurse where output tracked across the adhesive ('3 o'clock' or '9 o'clock') pinpoints the exact crease.
Know leak soreness vs. pressure soreness
Stinging right against the stoma edge points to leakage; a red ring further out under the dome points to excess convex pressure.
Order samples via your nurse before changing FP10s
Your NHS stoma nurse can arrange 5-pouch trial packs before updating your GP/DAC repeat prescription.

UK flat vs. convex stoma bag FAQs

Can I order convex stoma bags directly from my DAC without seeing a nurse?

UK clinical guidelines (ASCN UK) strongly advise having a stoma care nurse assess your abdomen before starting convex pouches—using inappropriate convexity over a firm tummy or parastomal hernia risks pressure ulcers.

What does 'soft convex' mean on UK stoma pouches?

Soft convex pouches feature a supple, compressible dome that flexes as you bend and walk, offering gentler support for flush stomas than traditional rigid convex inserts.

Should I use a mouldable ring with a convex stoma bag?

Sometimes a slim mouldable ring helps fill a side crease, while in other cases a convex pouch seals better directly on clean dry skin—your stoma nurse will help you test which gives the cleanest wear time.

How soon should my stoma nurse review me after starting convexity?

Typically within 7 to 14 days (or sooner if you feel any pinching, bruising, or discomfort) to confirm the peristomal skin looks healthy and pressure-free.

More free SIIL interactive tools for UK ostomates

UK clinical reference sources: Informed by ASCN UK National Clinical Guidelines (Convexity in Stoma Care), NHS Stoma Care, and Colostomy UK. Educational guide; always consult your NHS stoma care nurse before changing appliance convexity.

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