CPT 81110 HPA‑6 Genotyping Reimbursement

CPT code 81110 denotes a molecular diagnostic genotyping test that identifies the two common alleles of Human Platelet Antigen 6 (HPA–6), also called R489Q, using specimens such as blood or amniotic fluid. The code captures the technical laboratory component of allele analysis performed by a laboratory analyst. Nationally, molecular platelet antigen testing is important for managing alloimmune platelet disorders, prenatal risk assessment, and transfusion compatibility testing.

Key payers included in the analysis are Aetna, Blue Cross Blue Shield, Cigna Health, UnitedHealthcare, and Medicare. Readers will find an overview of clinical context for HPA–6 genotyping, typical sites of service where testing is performed, and the scope of billing activity tied to CPT code 81110. The publication outlines common billing modifiers and service-line considerations when available, notes typical laboratory workflows, and summarizes how this specific genotyping code fits into broader molecular diagnostics and transfusion medicine practice.

This summary is written for a national audience and aims to provide clinicians, billing professionals, and policy analysts with clear context on what CPT code 81110 represents, why HPA–6 testing matters clinically, and what elements are generally considered when this service is billed.

Billing Code Overview

CPT code 81110 describes a laboratory technical procedure to analyze the genes for the two common alleles of Human Platelet Antigen 6 (HPA–6), also known as R489Q, using a biological specimen such as blood or amniotic fluid. This is a molecular diagnostic test performed by a laboratory analyst to determine HPA–6 allele status.

Service type: Molecular diagnostic genotyping
Typical site of service: Clinical laboratory or hospital laboratory specialized in molecular testing

Clinical Context

A pregnant patient undergoes targeted platelet antigen genotyping when there is concern for maternal alloimmunization to fetal platelet antigens or when planning transfusion support. Typical scenarios include a woman with a prior pregnancy complicated by neonatal alloimmune thrombocytopenia (NAIT), a history of fetal or neonatal intracranial hemorrhage, or an obstetric history of unexplained fetal thrombocytopenia. A specimen (peripheral blood or amniotic fluid) is sent to a molecular diagnostics laboratory for analysis of Human Platelet Antigen 6 (HPA-6, also called R489Q) alleles. The laboratory technologist performs DNA extraction, PCR-based allele discrimination or sequencing, and reports genotype results (e.g., HPA-6a/HPA-6a, HPA-6a/HPA-6b, HPA-6b/HPA-6b). Results inform obstetric management (risk assessment for NAIT), selection of antigen-negative platelet units if transfusion is needed, and counseling of parents regarding recurrence risk. Typical site of service is a hospital-based or independent clinical molecular diagnostics laboratory; specimens are collected from outpatient clinics, inpatient obstetric units, or maternal-fetal medicine practices.

Coding Specifications

Modifier	Description	When to Use
`26`	Professional component	Use when billing only the physician/interpretive portion if the laboratory separates technical and professional components and the interpreter bills separately.

Taxonomy Code	Specialty	Notes
208000000X	Pathology and Laboratory Medicine	Clinical molecular pathology or clinical laboratory that performs molecular diagnostic testing.
207Q00000X	Obstetrics & Gynecology	Maternal-fetal medicine specialists ordering the test for alloimmunization risk assessment.
207L00000X	Pediatrics	Neonatology or pediatric hematology following affected newborns or consulted for NAIT.
208100000X	Clinical Geneticist	Medical geneticists interpreting hereditary platelet antigen results and counseling families.
2084P0800X	Hematology	Transfusion medicine or hematology specialists involved in platelet transfusion decisions.

Related Diagnoses

ICD-10 Code	Description	Clinical Relevance
`D69.5`	Primary thrombocytopenia	Relevant when evaluating maternal or neonatal thrombocytopenia and considering alloimmune causes.
`D69.6`	Thrombocytopenia, unspecified	Used when thrombocytopenia is present but the precise etiology is being investigated, including HPA incompatibility.
`O36.5XX0`	Maternal care for known or suspected fetal abnormality and damage, unspecified trimester, not applicable or unspecified	Used by obstetricians when fetal disorder (e.g., risk of NAIT) requires specialized evaluation; select appropriate subcode for trimester and encounter.
`P61.2`	Neonatal alloimmune thrombocytopenia	Directly related; HPA genotyping confirms antigen incompatibility between mother and fetus/neonate.
`Z31.6`	Encounter for genetic counseling	Used when genetic counseling is provided regarding recurrence risk of platelet antigen incompatibility.

Related CPT Codes

CPT Code	Description	Relationship to This Procedure
`81162`	HLA class I typing, sequence-specific oligonucleotide probe (SSOP) or sequence-based typing (SBT)	Performed when broader platelet or HLA compatibility is needed for platelet transfusion planning; may be ordered alongside HPA typing.
`81479`	Unlisted molecular pathology procedure	Used for molecular tests that do not have a specific CPT; rarely used if HPA-6 testing is performed by a method without an assigned code.
`82948`	Blood count; platelet count	Commonly performed in newborns or pregnant patients to document thrombocytopenia associated with alloimmune platelet disease.
`87491`	Infectious agent detection by nucleic acid (e.g., PCR), single organism	Not directly related but may be performed in parallel testing workflows in molecular labs; typically unrelated.
`36415`	Collection of venous blood by venipuncture	Specimen collection code commonly used when peripheral blood is drawn for HPA genotyping.

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Summary & Overview

CPT 81110: HPA-6 (R489Q) Genotyping, Technical Component