Clinical Context
A 32-year-old pregnant woman is referred to a maternal-fetal medicine clinic after routine prenatal blood work shows a history of previous neonatal alloimmune thrombocytopenia (NAIT) in a prior pregnancy. The obstetrician orders targeted platelet antigen genotyping to determine parental and fetal Human Platelet Antigen status. A phlebotomy technician collects a maternal blood specimen; when fetal genotype is needed and noninvasive methods are insufficient, amniocentesis may be performed and amniotic fluid sent to the molecular laboratory. In the molecular lab, a trained laboratory analyst performs the technical assay to determine the genotype of the two common alleles of Human Platelet Antigen 2 (HPA–2 / T145M). Results are reported to the ordering clinician and incorporated into prenatal counseling and intrapartum management planning, including platelet transfusion strategy if NAIT risk is identified. Typical workflow steps: order entry by clinician, specimen collection (blood or amniotic fluid), sample accessioning, DNA extraction, targeted HPA-2 genotyping assay run by the lab analyst, result verification by a supervising molecular pathologist or laboratory director, and release of results to the clinician and medical record.
Coding Specifications
| Modifier | Description | When to Use |
|---|
26 | Professional component | When billing only the professional interpretation or supervision if the lab separates technical and professional components. |
59 | Distinct procedural service | When HPA-2 genotyping is a distinct service from separate procedures performed the same day (use cautiously for NCCI compliance).
62 | Two surgeons | Rare for this lab test; used if two surgeons are medically necessary for an associated invasive procedure (e.g., amniocentesis) where applicable.
78 | Unplanned return to the OR following initial procedure | Applies only to related operative service such as management of amniocentesis complications requiring return to OR.
80 | Assistant surgeon | Applies to operative services related to specimen procurement when an assistant surgeon is involved.
90 | Reference (outside) laboratory | When the performing laboratory is an outside reference lab billing the test technical component.
TC | Technical component | When billing only the technical component of the molecular assay (equipment, reagents, technician time).
XU | Unusual non-overlapping service | When the service is distinct and separate from other services by a different provider not normally billed together.
AS | Physician assistant, nurse practitioner, or clinical nurse specialist services for assistant at surgery | Applicable only to associated procedures where an advanced practice clinician serves in an assistant role.
52 | Reduced services | When the lab test was partially completed or a reduced service was provided (e.g., insufficient sample requiring limited testing).
| Taxonomy Code | Specialty | Notes |
|---|
207Q00000X | Clinical Molecular Genetics Laboratory | Laboratory specialty that performs molecular genotyping and reporting. |
207L00000X | Clinical Laboratory | General clinical laboratory oversight and technical staff perform testing.
208D00000X | Obstetrics & Gynecology | Ordering clinicians managing prenatal care and decision-making based on results.
2080P0206X | Maternal-Fetal Medicine | Specialists who frequently order and interpret fetal platelet antigen genotyping in high-risk pregnancies.
208000000X | Pathology | Molecular pathologists who review and verify genetic test results.
Related Diagnoses
| ICD-10 Code | Description | Clinical Relevance |
|---|
O36.80X1 | Maternal care for other fetal problems, first trimester | Used when fetal platelet antigen risk is assessed early in pregnancy as part of prenatal evaluation. |
O36.80X2 | Maternal care for other fetal problems, second trimester | Used when HPA genotyping is performed in the second trimester for fetal risk assessment.
O36.80X3 | Maternal care for other fetal problems, third trimester | Used when testing is done late in pregnancy to guide intrapartum management.
D69.5 | Secondary thrombocytopenia | Relevant when maternal or fetal thrombocytopenia is suspected and platelet antigen incompatibility is investigated.
P61.2 | Neonatal alloimmune thrombocytopenia | Directly related diagnosis for which HPA genotyping is indicated to identify causative platelet antigen incompatibility.
Z34.80 | Encounter for supervision of other high-risk pregnancy | Used when pregnancy is high-risk due to previous NAIT or alloimmunization and genotyping is part of surveillance.
Z31.89 | Encounter for other general counseling and advice on procreation | Applied when genetic counseling accompanies targeted platelet antigen testing.
Z13.79 | Encounter for other screening for specified infectious and parasitic diseases and genetic disorders | Used when targeted genetic screening, including platelet antigen genotyping, is performed in a screening context.
Related CPT Codes
| CPT Code | Description | Relationship to This Procedure |
|---|
36415 | Collection of venous blood by venipuncture | Commonly used to obtain the maternal blood specimen for HPA-2 genotyping. |
59000 | Amniocentesis, diagnostic, any gestational age; without ultrasound guidance | Procedure used to obtain amniotic fluid when fetal genotype is required; specimen sent for genotyping.
0612U | Platelet antigen genotyping, non–FDA cleared, HPA variants (example entry-level molecular code) | Other specialized molecular assays for platelet antigen variants that may be performed alongside or as alternative targeted assays (lab-specific proprietary tests).
88342 | Immunohistochemistry or in situ hybridization interpretation — special stains (molecular adjunct) | Occasionally used when adjunct testing or validation with special stains or ISH is performed in complex diagnostic workflows.
G0452 | Molecular pathology services (example for Medicare molecular testing) | Administrative or payment-specific molecular testing group codes used in some Medicare contexts for high-complexity molecular assays.