Flow Cytometry - (0538) — MM 0538 | CIGNA Coverage Update

Cigna modified MM 0538, its flow cytometry coverage policy, effective October 16, 2025. Here's what billing teams need to do.

Cigna Healthcare updated Coverage Policy MM 0538 governing flow cytometry testing. This change affects 14 CPT codes — including 88184, 88185, 88187, 88188, and 88189 for technical and interpretation components — across hematology, oncology, immunology, and transplant medicine. If your practice or lab bills flow cytometry for hematologic malignancies, HIV/AIDS monitoring, or post-transplant surveillance, this policy update is worth a careful read before October 16, 2025.

Quick-Reference Table

Cigna Flow Cytometry Coverage Criteria and Medical Necessity Requirements 2025

The Cigna flow cytometry coverage policy under MM 0538 ties medical necessity to a defined set of clinical indications. Flow cytometry — the lab technique used to separate, classify, and count cell populations — is covered when ordered for diagnosis or evaluation of hematologic cancers, HIV/AIDS, primary immunodeficiency disorders, molar pregnancies, paroxysmal hemoglobinuria, or monitoring after transplantation.

All 14 CPT codes under this policy are designated "Considered Medically Necessary when criteria in the applicable coverage section are met." That language is doing a lot of work. It means coverage isn't automatic — the diagnosis on the claim must align with Cigna's approved indication list, and your documentation must support it.

The marker interpretation codes carry their own logic. CPT 88187 covers interpretation of two to eight markers. CPT 88188 covers nine to 15 markers. CPT 88189 covers 16 or more markers. Bill the code that matches the number of markers actually interpreted, as documented in the lab report.

CPT 88184 covers the technical component for the first marker. Each additional marker uses CPT 88185. These pair with the interpretation codes — make sure your lab is capturing both components if you perform and interpret in-house.

The specialty immunology codes — 86355 (B cells), 86357 (NK cells), 86359 (T cells, total count), 86360 (CD4/CD8 absolute count with ratio), 86361 (absolute CD4), and 86367 (CD34 stem cells) — each require a covered indication to be present on the claim. For HIV management specifically, CD4 monitoring via 86360 and 86361 maps directly to ICD-10 B20. If your infectious disease practice orders these routinely, confirm your ICD-10 assignment before October 16.

CPT 0581U is the proprietary lab test code for non-HLA antibody testing via flow cytometry in transplant medicine. It falls under the same medical necessity criteria framework. If your transplant center bills 0581U, the covered indication must tie to post-transplant monitoring — not a general pre-transplant workup without documented clinical rationale.

Cigna Flow Cytometry Exclusions and Non-Covered Indications

The policy data does not enumerate a separate experimental or non-covered code list for MM 0538. Every CPT code in this policy carries the same conditional language: covered when criteria are met.

The practical exclusion is any claim where the ICD-10 code on the claim falls outside the covered indication list. Cigna's ICD-10 list for this policy runs to 235 codes. That's a wide net — but it has edges. Flow cytometry ordered for general wellness panels, undifferentiated symptom coding, or diagnoses that don't map to the policy's covered indications will deny.

The real issue here is specificity. A claim for CPT 88184–88189 with an unspecified or low-acuity ICD-10 will draw scrutiny. If the clinical picture supports a covered diagnosis — say, suspected lymphoma or confirmed HIV disease — code to the highest level of specificity the documentation supports.

Coverage Indications at a Glance

Editorial note: The table below summarizes covered clinical indications based on the MM 0538 policy summary and ICD-10 code list. All 14 CPT codes under this policy are covered when medical necessity criteria are met — the source does not map specific CPT codes to specific indications. The ICD-10 codes shown are drawn from the source data and are not exhaustive. Verify all code assignments against the full MM 0538 policy text before billing.

All 14 CPT codes listed under MM 0538 are covered when medical necessity criteria are met. The source does not designate specific CPT codes for specific indications. View the complete ICD-10 list on PayerPolicy →

Cigna Flow Cytometry Billing Guidelines and Action Items 2025

CPT, HCPCS, and ICD-10 Codes for Flow Cytometry Under MM 0538

Covered CPT Codes (When Medical Necessity Criteria Are Met)

Key ICD-10-CM Diagnosis Codes

This policy covers 235 ICD-10 codes. Below are the highest-volume and highest-stakes codes your billing team should know cold.

The full ICD-10 list for MM 0538 includes 235 codes. View the complete list on PayerPolicy →