HCPCS code A4426: Ostomy pouch billing, Medicare, and fee schedule

Key takeaways

HCPCS code A4426 covers a drainable ostomy pouch made for a barrier with a locking flange in a 2-piece system.

The unit of service is each. One billed unit equals one pouch, and the code carries no per-10 package quantity.

Medicare Part B covers A4426 as a DMEPOS supply under the Ostomy Supplies LCD (L33828) when a physician order supports it.

The DME MAC quantity guideline for drainable pouches is 20 per month, which reaches the claim as 20 units of A4426.

A4427 is the same pouch with a filter added. Flange type does not separate the two codes, and both are billed each.

Practice management software like Pabau keeps the physician order, the dispensed quantity, and the diagnosis codes on one record.

HCPCS code A4426 describes a drainable ostomy pouch made for a barrier with a locking flange in a 2-piece system. Its unit of service is each, so 20 pouches means 20 units on the claim.

Billers who treat the code as a box of 10 understate every claim they send. Two details decide whether an A4426 claim pays. One is the exact product configuration, and the other is the unit count.

This reference covers the official descriptor, the unit of service, and Medicare fee schedule context. It also covers LCD coverage criteria, ICD-10 pairing, documentation, and the adjacent A4421 to A4437 codes.

HCPCS code A4426: official descriptor and code details

The Centers for Medicare and Medicaid Services (CMS) maintains the HCPCS Level II code set. A4426 carries the following official descriptor and code details.

The A-series (A0000 to A9999) holds the HCPCS Level II transport, medical, and surgical supply codes. A4426 sits inside the A4421 to A4437 ostomy cluster. Three attributes fix its identity. The pouch is drainable rather than closed, it fits a locking-flange barrier rather than a non-locking one, and it has no filter.

What HCPCS code A4426 covers

A4426 covers the pouch component only, not the barrier wafer, of a 2-piece drainable system. The pouch locks onto a separately coded barrier, so the patient can change pouches without lifting the skin barrier off the skin. One-piece systems, where the pouch and barrier are joined, carry different codes.

The code applies to fecal-output ostomies:

• Colostomy: surgical diversion of the colon through the abdominal wall, often after bowel resection or colorectal cancer surgery
• Ileostomy: surgical diversion of the ileum, commonly for Crohn’s disease, ulcerative colitis, or familial polyposis
• Other gastrointestinal diversions: stomas documented under Z93.4, where the patient wears a drainable pouch on a locking-flange barrier

Supply orders for those patients come from a few settings. Post-surgical follow-up sets the supply up, and primary care usually handles the renewals. Some come from the functional medicine practices treating the underlying bowel disease.

Urinary diversions do not use A4426. A urostomy pouch needs a faucet-type tap with a valve, and codes A4428 through A4434 describe those products. Sending a urostomy claim on A4426 is a product mismatch, even though both pouch types drain.

The drainable classification means the pouch has an openable outlet at the bottom. The patient empties it without taking the pouch off. Closed pouches, which carry their own codes, are discarded after each use. Drainable pouches suit higher-output stomas, where frequent full changes would be impractical.

The unit of service for A4426: one unit, one pouch

One unit of A4426 equals one pouch. The CMS long descriptor ends in the word each, and the code carries no package multiplier.

This is worth stating plainly, because several third-party billing summaries still describe 2-piece pouch codes as per 10. That convention does not apply here. A prescription for 20 drainable pouches is submitted as 20 units of A4426, not 2 units.

Most A-series supply codes are written the same way. A4490 also ends in each, so its unit count matches the number of items dispensed.

Getting this backwards under-bills the claim by a factor of ten. It also puts the unit count out of step with the proof of delivery, and that pairing is the first thing a post-payment reviewer compares. Suppliers who reconcile the two figures before submission rarely see a quantity denial.

A4426 Medicare fee schedule and reimbursement rates

Medicare pays A4426 from the DMEPOS fee schedule, not the Physician Fee Schedule. Look the allowance up in the CMS DMEPOS fee schedule file rather than a physician pricing tool, which does not price supply codes.

The payment framework for A4426 works like this:

State Medicaid programs publish their own flat per-unit rate for ostomy pouches, usually with a monthly unit cap that matches the Medicare guideline of 20. Those rates are set per unit, so the same one-pouch-per-unit logic applies. Check the applicable state fee file before you quote a figure.

Because allowances change quarterly and vary by state, treat any hardcoded dollar amount in a reference resource as illustrative. Only the current CMS file settles the rate. Wider Medicare billing rules then set the coinsurance and the deductible order.

When Medicare covers A4426: LCD L33828

Medicare Part B covers A4426 under the DMEPOS benefit when the patient has a surgically created ostomy and a valid physician order. The rules sit in the Ostomy Supplies LCD (L33828) and its Policy Article A52487, applied by the DME MACs.

Core coverage requirements include:

• A confirmed ostomy: the record must show a surgical colostomy or ileostomy, and the claim must carry the matching diagnosis code
• A physician order: the treating practitioner signs a written order naming the item and the quantity before the supplier bills
• Medical necessity in the file: ongoing need is usually established at surgery and carried forward, but it has to be produceable on request
• An enrolled supplier: the DMEPOS supplier must be Medicare-enrolled and accredited to bill ostomy supplies
• Quantities inside the guideline: the LCD sets a routine monthly allowance, and going above it without documentation triggers a coverage edit

The LCD guideline for drainable pouches is up to 20 per month. Because A4426 is billed each, the routine maximum on a monthly claim is 20 units. Larger quantities are payable, but the medical record has to explain why this patient needs more. Noridian and CGS both publish maximum-quantity tables for every ostomy code in their jurisdictions.

Documentation requirements for billing A4426

A paid A4426 claim rests on four documents the supplier has to be able to produce on request:

• Standard written order: patient name, order date, the item description or HCPCS code, the quantity, and the treating practitioner’s signature
• Proof of the ostomy: an operative report, discharge summary, or clinical note establishing the colostomy or ileostomy
• Proof of delivery: a dispensing record showing the date and the number of pouches actually supplied
• Refill documentation: evidence that the patient still needs and is still using the supply, dated before each new shipment

The quantity on the proof of delivery has to match the unit count on the claim. Twenty pouches delivered means 20 units billed, with no conversion step in between. A mismatch between those two numbers is the easiest recoupment a reviewer can write up.

Those four documents also have to be stored to federal standards. Working through a HIPAA compliance checklist is a practical way to confirm that.

ICD-10 diagnosis codes that support the claim

An A4426 claim needs an ICD-10 code that documents the ostomy itself, which is normally a Z93 status code. Underlying-condition codes support the claim but do not replace the status code. Capturing that detail on digital intake forms keeps it on the record from the first visit.

The codes below are the ones that appear most often on drainable pouch claims. They document medical necessity, but none of them guarantees payment on its own.

List the Z93 status code first on a supply claim, then add the underlying condition when the record supports it. Urinary status codes such as Z93.50 and Z93.6 do not belong on an A4426 claim, because A4426 is not a urinary pouch. Noridian and CGS publish the diagnosis codes each LCD accepts.

How to bill HCPCS code A4426: step by step

Four elements decide whether an A4426 claim pays. They are the code, the unit count, the modifier, and the supporting diagnosis. Claims management software that validates all four before submission cuts the denial rate. EHR integration keeps the order and the claim on the same record. Here is the standard workflow.

1. Confirm the product: check that the patient uses a 2-piece system with a locking-flange barrier, and that the pouch has no filter. A filtered pouch on the same barrier is A4427.
2. Count the pouches: bill one unit for every pouch supplied. Twenty pouches is 20 units. There is no division by 10 anywhere in this step.
3. Select the modifier: add KX when the record meets the LCD criteria. Use GA when the patient has signed an Advance Beneficiary Notice for an item likely to be denied. Confirm current modifier rules with the DME MAC.
4. Attach the diagnosis: include the Z93 ostomy status code, plus any underlying condition code the record supports. The codes on the claim must match the physician order and the chart.
5. Complete the CMS-1500 or 837P: A4426 and its modifier go in Box 24D. The unit count goes in Box 24G, and the ICD-10 codes in Box 21.
6. Submit to the DME MAC: ostomy supply claims go to the patient’s DME MAC rather than the local Part B contractor. That contractor also handles equipment claims such as K0808.

Keeping thorough medical forms at every step protects the practice during post-payment review. DME MACs run post-payment audits on ostomy supply claims, and suppliers without a complete file face recoupment.

Common billing errors for drainable ostomy pouches

Two error types cluster around A4426. One is the unit count, and the other is a product mismatch inside the A4421 to A4437 range. Thin refill and patient compliance records make a third. Here are the frequent mistakes and their fixes.

Patient data security tools keep a complete audit trail for supply orders and physician certifications. That trail protects the practice when a claim is pulled for review. Post-payment audits are routine for DMEPOS suppliers, and thin documentation is the most frequent recoupment trigger.

Code history and effective dates

CMS maintains HCPCS Level II and publishes quarterly updates, with the main annual release taking effect on January 1. A4426 sits in the long-standing A4421 to A4437 ostomy cluster and currently carries the drainable locking-flange descriptor, billed each. Code status history matters for backdated claims and audit defense, so keep a record of the release you billed under.

Coding teams should subscribe to CMS update notices and read the annual HCPCS release each fall. Codes in the A4421 to A4437 range do get revised, and a deleted or reworded code produces an immediate rejection. The CGS coding verification resource carries further guidance for DMEPOS products billed through that jurisdiction.

Related ostomy supply HCPCS codes: A4421 to A4437

Three variables pick the right code in this range. They are the pouch type, the system type, and the barrier attachment method. Whether the pouch has a filter splits several of the pairs as well. Practice management software with a built-in HCPCS library cuts selection errors at the point of order. The table below carries the current CMS descriptors.

A4426 vs A4427: these two are the pair most often confused, and the reason is usually a misreading of the descriptors. A4427 covers the same drainable pouch on the same locking-flange 2-piece barrier, with a filter added. The filter is the only difference. Flange type does not separate them, and both are billed each.

A4426 vs A4425: A4425 is the non-locking flange counterpart, and it carries a filter as well. If the barrier uses a push-on fit rather than a lever-type locking mechanism, A4426 is the wrong code.

A4426 vs A4424: A4424 covers a one-piece drainable pouch with the barrier already attached and a filter included. A patient moving from a 2-piece to a 1-piece system needs both a code change and a new physician order.

A4426 vs A4428 and A4429: both of those codes describe urinary pouches, not fecal ones. Each has an attached barrier and a faucet-type tap with a valve, and A4429 adds built-in convexity. Neither belongs on a colostomy or ileostomy claim.

For a urostomy patient on a locking-flange 2-piece system, the parallel codes are A4433 and A4434. A4434 is the version with a faucet-type tap with valve. Reading the tap and the flange together is the fastest way to land on the right code.

How Pabau keeps ostomy supply claims accurate

Most ostomy claim errors start upstream, in how the supply order is captured and matched to a code. A practice working from paper delivery notes re-keys the pouch count into the claim by hand, and that is where 20 units becomes 2.

Practice management software like Pabau keeps the physician order, the dispensed quantity, the HCPCS code, and the claim status together on one patient record. The unit count on the claim comes from the dispensing record rather than from memory. A mismatch shows up before the claim leaves the practice.

For suppliers running recurring monthly ostomy orders, the same record keeps refill dates, standing orders, and diagnosis codes linked. A stale order surfaces before it holds up a batch of claims, so a month of shipments bills cleanly the first time.

Reduce DMEPOS claim denials with Pabau

Pabau’s claims management software helps billing teams match unit counts to the dispensing record and validate HCPCS codes before submission. See how it works for your practice.

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Conclusion

A4426 is a narrow code, and that precision is what makes it error-prone. The descriptor fixes three attributes at once. The pouch is drainable, it has no filter, and it fits a locking-flange 2-piece barrier.

The unit of service is the detail worth correcting first. One unit is one pouch, so a routine monthly maximum of 20 pouches bills as 20 units. Any workflow that divides the pouch count by 10 understates every claim it touches.

Pabau helps DMEPOS billing teams track supply codes and tie unit counts to the dispensing record. It also holds the documentation trail that post-payment review asks for. To see how that shortens claim processing time, book a demo with the Pabau team.

Continue your research

Billing the catch-all ostomy supply code? HCPCS code A4421 covers when the miscellaneous code is appropriate and what documentation a DME MAC expects with it.

Dispensing closed pouches instead of drainable ones? HCPCS code A4423 is the closed pouch for a locking-flange barrier with a filter.

Wondering whether every supply code is billed each? HCPCS code A4259 is billed per box, which is a useful contrast when you set up unit counts.

Billing another DMEPOS supply on the same rules? HCPCS code A4490 shows how the each convention works outside the ostomy range.

Coding an orthosis rather than a supply? HCPCS code L1010 walks through DMEPOS orthosis documentation and where the claim goes.

Frequently asked questions