Summary & Overview
CPT 81107: HPA‑3 (I843S) Platelet Antigen Genotyping
CPT code 81107 represents a laboratory technical procedure for genotyping the two common alleles of Human Platelet Antigen 3 (HPA–3/I843S). This molecular diagnostic test identifies platelet antigen variants that can be relevant for alloimmunization, transfusion compatibility, and certain maternal–fetal platelet disorders. As genetic testing expands, accurate coding for targeted allele analysis informs clinical workflows, lab reporting, and payer adjudication nationwide.
Key payers covered in this analysis include Aetna, Blue Cross Blue Shield, Cigna Health, UnitedHealthcare, and Medicare. The publication outlines how CPT code 81107 is used across clinical laboratories, typical sites of service, and the clinical contexts prompting HPA–3 testing.
Readers will learn operational and policy-relevant details including common service settings, clinical indications for HPA–3 genotyping, and the kinds of benchmarks and policy updates to monitor for molecular diagnostic codes. Where specific data elements are not provided in the source input, the text notes that those items are not available. The summary focuses on the code’s clinical purpose, payer landscape, and the practical implications for laboratory services and billing workflows in a national context.
Billing Code Overview
CPT code 81107 describes a molecular diagnostic laboratory test that identifies the two common alleles of Human Platelet Antigen 3 (HPA–3), also known as I843S. The procedure is performed by a laboratory analyst who conducts the technical component of the genetic analysis using a biological specimen such as blood or amniotic fluid.
Service Type: Genetic testing / molecular diagnostic technical component
Typical Site of Service: Clinical laboratory or hospital laboratory
Clinical & Coding Specifications
Clinical Context
A 32-year-old pregnant woman is referred for thrombocytopenia workup after routine prenatal labs identify low platelet counts and a family history of neonatal alloimmune thrombocytopenia (NAIT). The obstetrician collects a maternal peripheral blood specimen; the laboratory performs 81107 testing to genotype the two common alleles of Human Platelet Antigen 3 (HPA‑3, I843S) to determine maternal and, if available, paternal or fetal antigen status. Results guide risk assessment for NAIT, donor selection for platelet transfusion, and prenatal counseling. Typical workflow: specimen collection (mother, father, or amniotic fluid), accessioning, DNA extraction, allele‑specific PCR or sequencing for HPA‑3, analytic validation, result verification by a clinical laboratory scientist, and final reporting to the ordering obstetrician, maternal‑fetal medicine specialist, or transfusion service. Typical sites of service include hospital clinical molecular laboratories, reference genetic testing laboratories, and maternal‑fetal medicine outpatient clinics coordinating specimen shipment. Testing is commonly ordered when maternal immunization against platelet antigens is suspected, in neonatal thrombocytopenia evaluation, or prior to platelet transfusion planning for sensitized patients.
Coding Specifications
| Modifier | Description | When to Use |
|---|---|---|
26 | Professional component | Use when only the professional interpretation/reporting component is billed separately from the technical lab work. |