Summary & Overview
CPT 86355: B-Cell Quantitation, Blood
CPT code 86355 represents a laboratory immunology test that quantifies B lymphocytes in a patient’s blood. Nationally, this code is important for assessing immune function in conditions such as immunodeficiency, monitoring after immunosuppressive therapy, and guiding diagnostic workups for hematologic and autoimmune disorders. Use of this code affects laboratory billing, clinical management, and payer coverage decisions across outpatient and hospital settings.
Key payers covered in this analysis include Aetna, Blue Cross Blue Shield, Cigna Health, UnitedHealthcare, and Medicare. Readers will find a concise overview of the clinical purpose of 86355, common sites and service contexts where it is performed, and which major payers are relevant for coverage considerations. The publication also outlines benchmarks and policy-relevant updates where available, along with guidance on documentation expectations and common billing considerations tied to laboratory immunology testing.
This summary provides a national perspective on clinical context and payer relevance for CPT code 86355, intended to inform billing staff, laboratorians, and policy analysts about what the code represents and where it fits into diagnostic workflows and reimbursement frameworks.
Billing Code Overview
CPT code 86355 describes a laboratory test that measures the quantity of B cells in the immune system, typically using a sample of the patient’s blood. This test is used to evaluate B-lymphocyte populations for clinical assessment of immune status.
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Service type: Laboratory quantitative immunology test
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Typical site of service: Clinical laboratory or hospital laboratory (blood draw may occur in an outpatient clinic, hospital, or phlebotomy center)
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Clinical & Coding Specifications
Clinical Context
A typical patient is an adult referred by a hematologist or immunologist for quantification of B lymphocytes to evaluate suspected or known immune deficiency, autoimmune disease, monitoring of immunomodulatory therapy, or pre-/post-treatment assessment for B-cell–targeted biologics. The patient presents to an outpatient phlebotomy lab or hospital outpatient blood-draw station. A licensed phlebotomist collects peripheral blood into appropriate EDTA tube(s). The specimen is labeled and transported to the clinical laboratory. A medical laboratory scientist or flow cytometry technologist performs B-cell enumeration, commonly via flow cytometry detecting markers such as CD19 and CD20. Results are reviewed by a pathologist or laboratory director, reported in the electronic medical record, and communicated to the ordering clinician for interpretation and management decisions. Typical sites of service include outpatient laboratory/ambulatory phlebotomy centers, hospital outpatient departments, and inpatient hospital laboratories when ordered during admission.
Coding Specifications
| Modifier | Description | When to Use |
|---|---|---|
26 | Professional component | Use when only the professional interpretation/reporting portion is billed separately from the technical component. |
TC |