KOSA Medical · Buying Guide

How to Select Medical Underpads: Size, Absorbency, Breathability and Adhesive Backing

A practical selection framework for disposable medical underpads — how to size the pad, read absorbency and rewet data, choose between breathable and non-slip backing, and decide when adhesive tabs are worth the cost.

Published August 18, 2026 · Updated September 8, 2026 · KOSA Medical

Key Takeaways

Size the pad to the surface and the dwell time, not to the mattress label.
Specify capacity plus retention under load plus rewet — capacity alone is not comparable.
Non-slip backing and adhesive tabs cost little and remove the most common complaint.
Breathable backsheets are for long dwell, not for high output.
Convert every option into cost per patient day before comparing prices.

Start from the use case, not from the product list

Most underpad complaints trace back to a format mismatch rather than a quality defect. A pad that is too small migrates and leaks at the edge; a pad that is too large for a short procedure wastes money on every change. Write down the surface, the typical output and the dwell time first, then match the format.

Step 1 — Size and format

Format	Typical size range	Where it is used	Notes
Chair / small protector	approx. 33 × 45 cm	Wheelchairs, day rooms, outpatient	Light output, frequent changes
Standard bed protector	approx. 60 × 60 to 60 × 90 cm	General ward, long-term care	The default workhorse format
Large / full-bed	approx. 80 × 150 cm and up	Bariatric, night use, high output	Reduces full linen changes
Procedure underpad	Per sterile field requirement	Procedure rooms, minor surgery	Often requires sterile presentation

Step 2 — Absorbency, retention and rewet

Three numbers describe real performance, and you need all three:

Total absorbent capacity — the total volume held. Useful for sizing, misleading on its own.
Retention under load — how much stays in the core when body weight is applied. This predicts rewet better than any other figure.
Rewet / wet-back — how much fluid returns to the surface under pressure. This is what the patient actually feels and what leads to skin maceration.

Acquisition or strike-through time is worth recording as a fourth figure, because it drives the perceived dryness, but it should never be used as a substitute for retention.

Step 3 — Backing: barrier, breathability, slip

Backing option	Strength	Limitation	Choose when
Standard PE film	Strongest fluid barrier, lowest cost	Can feel warm, can slide	General ward, short dwell
Non-slip textured film	Stays in place, fewer repositionings	Slightly higher cost	Long-term care, restless patients
Breathable film	Better comfort on long dwell	Lower absolute barrier margin	Long dwell with moderate output
Adhesive corner tabs	Locks the pad to linen	Slower to remove, adhesive residue risk	Night use, high-movement cases

Step 4 — Convert everything to cost per patient day

Unit price is the least useful number in this category. A pad that costs 15% more but survives one extra hour before saturation usually reduces both the number of pads and the number of linen changes, which is where the real labour cost sits. Run a two-week trial on each shortlisted option, count pads and linen changes per patient day, then multiply.

A short specification template

1. Format and dimensions

State length × width and tolerance, and whether sealed edges are required.

2. Core construction

Fluff grammage, SAP ratio, total core weight, and whether an ADL is present.

3. Performance data

Capacity, retention under load, rewet and strike-through, each with the test method named.

4. Backing and fixing

Film type, breathability, non-slip treatment, adhesive tabs.

5. Packaging and logistics

Pieces per bag, bags per carton, carton dimensions — this drives freight cost more than pad price in many export lanes.

Frequently Asked Questions

What size underpad should I use for a standard hospital bed?

For general ward use a 60 × 90 cm bed protector placed under the patient's torso covers the highest-risk area without the cost of a full-bed format. Move to a large or full-bed format for night use, bariatric patients or high output, where the saving comes from avoiding full linen changes.

Is a breathable backing always better?

No. Breathable films improve comfort during long dwell times but provide a lower absolute fluid barrier than solid PE film. Use them where dwell is long and output is moderate; specify solid film where output is high or unpredictable.

When are adhesive corner tabs worth the extra cost?

Adhesive tabs pay for themselves when pad migration is causing extra staff time — typically night shifts, restless patients and long-term care. They are less useful for short procedures or low-mobility day use where the pad stays put.

How do I compare absorbency claims between two suppliers?

Ask both for the same three figures measured under the same test method: total capacity, retention under load and rewet. If a supplier will only quote a single 'absorbency' tier without the method, treat the offer as non-comparable.

Should the pad be changed on a fixed schedule?

A fixed schedule is a reasonable starting point, but the better method is to observe actual saturation during a trial and set the interval from that. Fixed schedules on high-output patients lead to leaks; on low-output patients they waste pads.