HCPCS code A4368: Ostomy filter billing and Medicare coverage

Key Takeaways

HCPCS code A4368 is the active Level II supply code for an ostomy filter, any type, each, covered under Medicare Part B’s Prosthetic Device benefit.

Claims must be submitted by an enrolled DMEPOS supplier, not a physician office, and require a qualifying ostomy diagnosis (Z93.3 colostomy, Z93.2 ileostomy, or Z93.6 urostomy) plus a physician order.

CMS has not published an explicit numeric monthly maximum for A4368; quantity must be supported by documented medical necessity and checked against the supplier’s MAC or payer-specific policy.

Practice management software like Pabau can support DMEPOS documentation with digital intake and consent capture, plus a centralized patient record that keeps physician orders and proof of delivery ready for a MAC audit.

HCPCS code A4368 is the Level II supply code for an ostomy filter, any type, each, billed under Medicare Part B’s Prosthetic Device benefit for patients with a colostomy, ileostomy, or urostomy.

This guide covers the code’s coverage criteria, qualifying ICD-10 diagnosis codes, quantity guidance, documentation requirements, the fee schedule, related codes, and the denial patterns that generate the most rework for DMEPOS suppliers.

HCPCS code A4368 at a glance

A4368 is an active HCPCS Level II code maintained by the Centers for Medicare and Medicaid Services (CMS). It belongs to the A-series (A4000 range) of medical and surgical supplies.

Ostomy supplies like A4368 are billed under Medicare’s Prosthetic Device benefit, administered by the DME MACs. The code has been active since at least the early 2000s and remains billable in 2026 with no termination date.

The descriptor “any type, each” means a single billing unit covers one filter regardless of manufacturer or filter design. Suppliers do not need separate codes for charcoal-based versus membrane-based filters.

What does an ostomy filter do?

Ostomy filters attach to the gas-release vent on a colostomy, ileostomy, or urostomy pouch. They serve two clinical purposes: Neutralizing odor from intestinal gas and controlling the rate at which gas escapes through the pouch, preventing ballooning and blowout. For patients who are active or employed, filters are a quality-of-life essential, not a convenience item.

Medicare’s coverage rationale rests on this clinical function. The filter is medically necessary when its absence would cause repeated pouch failure, skin breakdown from leakage, or social isolation that impairs patient wellbeing. A physician order documenting these patient-specific needs is always required, whether it originates from a general practice managing long-term ostomy care or a physical therapy practice supporting post-surgical recovery.

• Colostomy patients: Gas production varies significantly with diet; filters prevent embarrassing pouch inflation during daily activity.
• Ileostomy patients: Output consistency differs from colostomy; filters manage odor without requiring frequent pouch emptying.
• Urostomy patients: Filters are less commonly prescribed but may be used on specific pouch models; confirm medical necessity documentation is specific to the patient’s ostomy type.

Medicare coverage criteria for A4368

Medicare Part B covers A4368 under the Prosthetic Device benefit when all of the following conditions are met. CMS Policy Article A52487 governs coverage for all ostomy supplies, including filters.

• The beneficiary has a permanent or temporary colostomy, ileostomy, or urostomy confirmed by medical records.
• A physician (or qualified non-physician practitioner) has written a valid order for the ostomy filter.
• The filter is dispensed and billed by a Medicare-enrolled DMEPOS supplier. Physician offices and hospital outpatient departments may not bill A4368 directly.
• The claim is submitted to the appropriate Medicare Administrative Contractor (MAC) for the supplier’s jurisdiction.
• The quantity billed is supported by documented medical necessity and does not exceed any applicable payer-specific limit (CMS does not publish a specific numeric monthly cap for A4368).

Coverage applies across all three ostomy types. Commercial insurance and state Medicaid programs may use different criteria; this article is scoped to Medicare Part B only. Always verify coverage criteria with the specific payer before billing non-Medicare claims.

Qualifying diagnoses: ICD-10 codes for A4368

Every A4368 claim requires a supporting ICD-10-CM diagnosis code that establishes the patient’s ostomy status. Per CMS Policy Article A52487, the qualifying diagnosis codes are Z93.2 (ileostomy), Z93.3 (colostomy), and Z93.6 (other artificial openings of urinary tract status, i.e. urostomy).

Using the wrong code or omitting a diagnosis code entirely is one of the most common denial triggers.

Z93.2, Z93.3, and Z93.6 are the diagnosis codes CMS Policy Article A52487 recognizes as covering A4368. The Z93.5x cystostomy codes (Z93.50, Z93.51, Z93.59) may be clinically accurate for certain urinary diversions, but they are not on CMS’s covered-code list for this policy — confirm with your MAC or payer before relying on a Z93.5x code as the primary billing diagnosis.

If a patient has multiple ostomy diagnoses, list the most specific code first on the claim.

Medicare quantity limits for A4368

CMS has not published an explicit numeric monthly maximum for A4368; it does not appear in LCD L33828’s “Usual Maximum Quantity of Supplies” table.

That doesn’t mean quantity is unlimited: Billed quantity must be supported by documented medical necessity (frequency of pouch changes, patient-specific need), and it should always be checked against your specific MAC’s policy, since some MACs and commercial or Medicaid payers set their own caps.

Billing a quantity that isn’t supported by documentation is the second most common reason A4368 claims are denied or flagged for audit.

Verify quantity expectations directly against CMS Policy Article A52487, LCD L33828, and your MAC’s local coverage article before billing, since CMS does not set a numeric cap and payer policies can differ.

Contact your applicable MAC (Noridian, CGS, Palmetto GBA, or others) if you serve beneficiaries across multiple regions, and check commercial or Medicaid payer policy separately, as those payers may apply their own caps.

A4368 documentation requirements

Documentation failures account for a significant share of A4368 denials. Medicare requires specific records at the time of claim submission, and your MAC may request these records during post-payment audits.

• Physician order: A written or electronic order signed by the treating physician or qualified non-physician practitioner. The order must specify the supply, quantity, and frequency. This is always required.
• Medical records confirming ostomy status: Operative report, discharge summary, or clinical notes documenting the ostomy creation or confirmation of existing ostomy. Records must establish that the patient has a qualifying ostomy type.
• Standard Written Order (SWO): CMS discontinued Certificates of Medical Necessity (CMNs) and DME Information Forms (DIFs) for all DME claims with dates of service on or after January 1, 2023. Ostomy supplies were never subject to a CMN requirement in the first place. What’s required instead is a Standard Written Order signed by the treating physician or qualified non-physician practitioner, on file before the claim is submitted.
• Proof of delivery: Documentation that the beneficiary received the supplies, including signature or acknowledgment where required.
• Supplier records: The enrolled DMEPOS supplier must retain all supporting documentation for a minimum of 7 years.

Using digital intake forms built into your practice management system can automate the capture of physician orders and patient consent at the point of supply, so nothing is missing from the file at audit time. Pair that with a centralized patient record management system so all ostomy documentation is accessible in one place for MAC reviews.

How to bill A4368: Claims submission guide

Submitting A4368 correctly requires attention to both the claim form fields and the underlying compliance requirements. Paper claims use the CMS-1500 form, while electronic submissions use the equivalent 837P fields. Only Medicare-enrolled DMEPOS suppliers may submit claims for this code. Physician offices and facilities are not eligible billing entities for A4368 under Part B.

Review your HIPAA compliance guide obligations before submitting electronic DME claims, as all Medicare DME claims must be transmitted in the ANSI X12 837P transaction format.

1. Confirm supplier enrollment: Verify your NPI and PTAN are active in PECOS as a DMEPOS supplier for the beneficiary’s MAC jurisdiction before submitting any claim.
2. Verify beneficiary eligibility: Confirm Medicare Part B coverage is active for the service date. Use your MAC’s eligibility verification tool or a real-time eligibility check through your billing system.
3. Obtain and file the physician order: Secure a written order before dispensing. The order date must precede or match the service date on the claim.
4. Select the correct ICD-10-CM code: Use the appropriate Z93.x code from the qualifying diagnoses table above. The diagnosis must appear in Box 21 (837P) or the equivalent electronic field.
5. Enter A4368 in the procedure field: Code goes in Box 24D. Units reflect the quantity dispensed (1 unit = 1 filter). Support any quantity billed with documented medical necessity, and verify against the applicable MAC or payer-specific policy since CMS does not publish a numeric monthly cap for A4368.
6. Submit to the correct MAC: Route the claim to the MAC serving the beneficiary’s home address, not the supplier’s address. DMEPOS claims follow beneficiary location rules.
7. Retain documentation: Store all supporting records for 7 years from the date of service, accessible for MAC audit request.

Streamline your DMEPOS documentation workflow

Practice management software like Pabau helps billing teams capture intake and consent digitally and keep supporting documentation organized in one patient record. See how it works for your practice.

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Medicare allowable fee for A4368

Medicare’s reimbursement rate for A4368 is set through the DMEPOS fee schedule, which CMS updates annually. Rates vary by MAC jurisdiction, which means a DMEPOS supplier in Noridian’s jurisdiction (covering states including California, Nevada, and Alaska) will see different allowable amounts than suppliers in CGS or Palmetto GBA territory.

Always look up current allowable amounts using the CMS fee schedule tool rather than relying on historical figures. DMEPOS fee schedules are updated each January 1. Specific dollar amounts published in third-party guides can be outdated within months of publication, making the CMS tool the only reliable source for current billing purposes.

Understanding how fee schedules work across private insurers is equally important for multi-payer billing teams. Resources covering private insurance fee schedules can help your team build payer-specific billing protocols alongside your Medicare workflows.

Medicare pays 80% of the allowable fee after the beneficiary meets the annual Part B deductible. The beneficiary is responsible for the remaining 20% coinsurance unless they have supplemental coverage. Suppliers may not bill above the Medicare allowable amount for beneficiaries with assignment accepted.

Related HCPCS codes for ostomy supplies

A4368 rarely appears on a claim in isolation. DMEPOS suppliers typically bill it alongside pouch codes like A4427, faceplate codes like A4361, and other adhesive products from the same A4000 series. Understanding the full code family reduces unbundling errors and improves claim accuracy.

For additional coding context across procedure types, see how Coaching CPT codes and IVF CPT codes illustrate the broader structure of procedure coding across specialties.

Key unbundling warning: If you are billing A4427 (2-piece drainable pouch with integrated filter, locking flange), do not also bill A4368 for a separate filter on the same claim line for the same unit. Review your MAC’s bundling edits before submitting co-billed claims.

Common denial reasons and how to avoid them

A4368 denials follow predictable patterns. Most can be prevented with pre-submission checks. Below are the denial scenarios most frequently reported for A4368 claims, along with the fix for each.

How practice management software streamlines A4368 billing

Manually tracking A4368 documentation requirements across a patient population is a compliance risk. A slip here costs more than one denied claim: it can trigger audit exposure, a repayment demand, and the staff time to appeal and resubmit. The most common failure points are:

• A physician order expires before it’s renewed.
• The wrong ICD-10 code gets selected on the claim.
• Billed quantities go unsupported by documentation.

Practice management software like Pabau helps with these failure points through documentation, not Medicare-specific automation. Digital intake and consent capture at the point of service creates a timestamped record of what was collected and when.

A centralized patient record then keeps physician orders, proof of delivery, and supporting notes in one place instead of scattered across paper files and email threads. For DMEPOS-adjacent practices, that organization is what speeds up a MAC audit response.

• Digital intake and consent: Patients complete forms and sign consents digitally at the point of service, creating a timestamped record instead of a paper form that gets scanned and filed later.
• Centralized patient record: Physician orders, proof of delivery, and supporting notes are stored against the patient record in one place, not scattered across paper files, email, or a separate scanning system.
• Audit-ready retrieval: When a MAC or payer requests records, staff pull the full documentation trail from one record instead of searching multiple systems.

Keeping intake, consent, and supporting documentation in one digital record reduces the administrative burden on billing staff and gives compliance teams a cleaner audit trail. When a MAC requests records, everything is already organized and retrievable in the patient’s file.

Conclusion

A4368 billing is straightforward when four requirements are met: A qualifying Z93.2, Z93.3, or Z93.6 diagnosis code, a valid physician order (SWO), a Medicare-enrolled DMEPOS supplier as the billing entity, and a quantity that’s supported by documented medical necessity. Denials almost always trace back to one of these four elements being missing or incorrect at claim time.

Practice management software like Pabau helps DMEPOS billing teams keep this documentation centralized and organized, so records are ready whenever a MAC asks for them. To see how Pabau’s digital intake and patient record tools work, book a demo with the team.

Continue your research

Need a reference for HCPCS code lookups? AAPC’s HCPCS Level II code search lets billing teams look up A-series supply codes, check descriptions, and cross-reference Medicare coverage in one tool.

Billing a related skin barrier? A4362 shares the same DMEPOS supplier and documentation rules as A4368.

Also billing diabetic supplies? A4259 follows the same DMEPOS quantity-documentation rules as A4368.

Frequently Asked Questions