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CPT 81508: PAPP–A and hCG Laboratory Assay with Algorithmic Risk Score

CPT code 81508 identifies a laboratory assay and algorithmic analysis that measures PAPP–A and hCG protein levels and combines those results with patient data to generate a reported risk score. This service represents the integration of biochemical measurement and software-driven risk modeling and is relevant to prenatal risk assessment and other clinical risk-stratification contexts. Nationally, the code matters because it distinguishes a combined laboratory-and-algorithm service from standalone analyte testing or separate interpretation services, affecting billing, coverage, and quality reporting.

Key payers discussed include Aetna, Blue Cross Blue Shield, Cigna Health, UnitedHealthcare, and Medicare. Readers will find a concise review of the clinical context for the assay, typical sites of service, and the service model under which the technical testing and algorithmic reporting occur. The publication also summarizes benchmarks for utilization and coverage constructs, outlines common modifiers associated with reporting the service, and highlights policy and coding considerations that influence reimbursement and payer review. Intended takeaways include clarity on what CPT code 81508 represents, where it is performed, and the major topics stakeholders consider when assessing coverage and claims for combined laboratory-and-algorithm tests.

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Billing Code Overview

CPT code 81508 describes a laboratory service in which the lab analyst measures two serum proteins, pregnancy-associated plasma protein A (PAPP–A) and human chorionic gonadotropin (hCG), and applies an algorithmic analysis that integrates those assay results with patient data to generate and report a patient risk score. The primary service type is laboratory-based biomarker testing with algorithmic risk assessment. The typical site of service is a clinical laboratory or an independent diagnostic testing facility (IDTF) where blood specimens are collected and processed and algorithmic software is applied to produce the reported risk score.

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CPT 81508: PAPP–A and hCG Laboratory Assay with Algorithmic Risk Score

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Billing Code Overview

Clinical & Coding Specifications

Clinical Context

A 12-week pregnant patient presents for first-trimester aneuploidy screening. The clinician orders maternal serum biochemical testing for pregnancy-associated plasma protein A (PAPP‑A) and free ß‑human chorionic gonadotropin (hCG) as part of a combined screening algorithm incorporating maternal age, gestational age, and ultrasound findings (nuchal translucency if available). A phlebotomy technician collects a maternal blood specimen at an outpatient laboratory or hospital outpatient drawing station. The specimen is routed to a reference laboratory where a clinical lab analyst performs the immunoassays for PAPP-A and hCG, validates assay performance, and enters patient demographic and clinical data into the lab information system. The laboratory information system applies a validated algorithm to integrate analyte concentrations with maternal age and gestational age to generate a patient-specific risk score for trisomy 21 and trisomy 18. The laboratory issues a structured report to the ordering obstetric clinician and uploads results to the electronic medical record. Typical sites of service include outpatient hospital laboratories, independent reference laboratories, and large ambulatory clinic laboratories. The service type is clinical laboratory testing with algorithmic risk calculation performed by the lab technical staff and reported as a combined biochemical screening result represented by CPT 81508.

Coding Specifications

Modifier	Description	When to Use
`26`	Professional component	Use when billing only the professional interpretation component if applicable for algorithm oversight or pathologist sign-out separated from the technical lab work.
`TC`	Technical component	Use when billing only the technical component for the laboratory testing and algorithmic computation performed by the lab.
`90`	Reference (outside) laboratory	Use when the test was performed by a laboratory other than the billing provider (reference lab).
`59`	Distinct procedural service	Use when this laboratory algorithmic test is distinct and separately reportable from another service on the same day not normally reported together.
`62`	Two surgeons	Rare in lab context; use only if two providers share responsibility in an unusual institutional billing arrangement.
`52`	Reduced services	Use when part of the service was medically unnecessary or partially performed resulting in reduced work or components.
`53`	Discontinued procedure	Use if testing was started but discontinued for valid clinical reasons before completion.
`76`	Repeat procedure by same provider	Use if the laboratory repeats the test for the same patient on the same day at the request of the ordering clinician (not in provided list; not applicable).
`59`	Distinct procedural service	(Duplicate row omitted)
`90`	Reference (outside) laboratory	(Duplicate row omitted)

Taxonomy Code	Specialty	Notes
`207Q00000X`	Clinical Laboratory	Clinical laboratory directors and technical supervisors who oversee algorithmic testing.
`208000000X`	Obstetrics & Gynecology	Ordering clinicians who request first-trimester aneuploidy screening.
`207L00000X`	Pathology	Pathologists providing oversight, validation, and interpretation of laboratory results.
`363A00000X`	Phlebotomy	Providers or technicians responsible for specimen collection in outpatient or hospital settings.
`3336C0004X`	Medical Genetics	Specialists who may interpret results for high-risk patients and counsel regarding prenatal screening outcomes.

Related Diagnoses

ICD-10 Code	Description	Clinical Relevance
Data not available in the input.	Data not available in the input.	Data not available in the input.

Related CPT Codes

CPT Code	Description	Relationship to This Procedure
`81025`	Urinalysis; automated dipstick	Performed at the clinic visit for routine prenatal screening; not directly related but commonly ordered during obstetric visits.
`36415`	Collection of venous blood by venipuncture	Phlebotomy code representing specimen collection required prior to the laboratory performing `CPT 81508`.
`76811`	Ultrasonic, pregnant uterus, real time with image documentation, fetal nuchal translucency measurement	Performed in first-trimester combined screening; nuchal translucency measurement is often integrated with `CPT 81508` results for final risk assessment.
`88360`	Immunohistochemistry or immunocytochemistry, per specimen; initial single antibody stain	Represents lab immunoassay methodologies conceptually similar to analyte testing though not used for `PAPP-A`/`hCG` specific immunoassays; included for workflow context.
`89250`	Routine cytogenetic analysis, prenatal sample	Used when abnormal screening results from `CPT 81508` prompt diagnostic testing such as chorionic villus sampling or amniocentesis with cytogenetic analysis.

CPT 81490: RA Disease Activity Score from 12-Serum Biomarker Panel

CPT-81493-CORONARY-ARTERY-DISEASE-23-GENE-RT-PCR-RISK-SCORE

CPT 81493: 23-Gene RT-PCR Test with Algorithmic CAD Risk Score

CPT-81500-CA125-HE4-ALGORITHMIC-RISK-SCORE

CPT 81500: CA-125 and HE4 Laboratory Testing with Algorithmic Risk Score

CPT-81503-ALGORITHMIC-LAB-RISK-SCORE-CA125-APOLIPOPROTEIN-A1

CPT 81503: Algorithmic Laboratory Risk Score Using Multiple Biomarkers

CPT-81504-TUMOR-ORIGIN-RNA-EXPRESSION-CLASSIFIER

CPT 81504: RNA Expression Tumor Origin Classifier

CPT-81506-DIABETES-BIOMARKER-PANEL-WITH-RISK-SCORE

CPT 81506: Diabetes Biomarker Panel with Algorithmic Risk Score

CPT-81507-NIPS-CELL-FREE-DNA-TRISOMY-RISK-ANALYSIS

CPT 81507: Non-Invasive Prenatal Screening for Trisomies 13, 18, 21

CPT-81509-LAB-ALGORITHMIC-RISK-ASSESSMENT-PAPP-A-HCG-DIA

CPT 81509: Laboratory Algorithmic Risk Assessment for PAPP–A, hCG, DIA

CPT-81510-PRENATAL-TRIPLE-MARKER-ALGORITHMIC-RISK-ASSESSMENT

CPT 81510: Prenatal Triple-Analyte Algorithmic Risk Assessment

CPT-81511-MULTIANALYTE-SERUM-SCREENING-ALGORITHMIC-RISK-SCORE

CPT 81511: Multianalyte Serum Screening with Algorithmic Risk Score

Showing 1–10 of 41

Frequently Asked Questions

References

1.CPT® Codes and Descriptions. AAPC. Retrieved Jul 29, 2026.
2.HCPCS Quarterly Update. Centers for Medicare & Medicaid Services (CMS). Retrieved Jul 29, 2026.
3.ICD-10-CM Full Code List. Centers for Medicare & Medicaid Services (CMS). Retrieved Jul 29, 2026.

Published by

Trek Health powers OpenPayer with a leading commercial payer intelligence platform, seamlessly converting fragmented payer data into actionable insights for provider organizations.

Trek Health ingests and normalizes Transparency in Coverage data and payer policy updates to give provider organizations a clear view of how commercial reimbursement behaves across markets, payers, and services. Our platform transforms raw payer disclosures into structured intelligence that supports contract evaluation, payer negotiations, and service line strategy. By combining market benchmarks with ongoing policy visibility, Trek helps teams identify variability, risk, and opportunity in commercial reimbursement. The result is faster insight, stronger negotiating positions, and more informed financial decisions.

Clinical & Coding Specifications

Clinical Context

Coding Specifications

Modifier	Description	When to Use
`26`	Professional component	Use when billing only the professional interpretation component if applicable for algorithm oversight or pathologist sign-out separated from the technical lab work.
`TC`	Technical component	Use when billing only the technical component for the laboratory testing and algorithmic computation performed by the lab.
`90`	Reference (outside) laboratory	Use when the test was performed by a laboratory other than the billing provider (reference lab).
`59`	Distinct procedural service	Use when this laboratory algorithmic test is distinct and separately reportable from another service on the same day not normally reported together.
`62`	Two surgeons	Rare in lab context; use only if two providers share responsibility in an unusual institutional billing arrangement.
`52`	Reduced services	Use when part of the service was medically unnecessary or partially performed resulting in reduced work or components.
`53`	Discontinued procedure	Use if testing was started but discontinued for valid clinical reasons before completion.
`76`	Repeat procedure by same provider	Use if the laboratory repeats the test for the same patient on the same day at the request of the ordering clinician (not in provided list; not applicable).
`59`	Distinct procedural service	(Duplicate row omitted)
`90`	Reference (outside) laboratory	(Duplicate row omitted)

Taxonomy Code	Specialty	Notes
`207Q00000X`	Clinical Laboratory	Clinical laboratory directors and technical supervisors who oversee algorithmic testing.
`208000000X`	Obstetrics & Gynecology	Ordering clinicians who request first-trimester aneuploidy screening.
`207L00000X`	Pathology	Pathologists providing oversight, validation, and interpretation of laboratory results.
`363A00000X`	Phlebotomy	Providers or technicians responsible for specimen collection in outpatient or hospital settings.
`3336C0004X`	Medical Genetics	Specialists who may interpret results for high-risk patients and counsel regarding prenatal screening outcomes.

Related Diagnoses

ICD-10 Code	Description	Clinical Relevance
Data not available in the input.	Data not available in the input.	Data not available in the input.

Related CPT Codes

CPT Code	Description	Relationship to This Procedure
`81025`	Urinalysis; automated dipstick	Performed at the clinic visit for routine prenatal screening; not directly related but commonly ordered during obstetric visits.
`36415`	Collection of venous blood by venipuncture	Phlebotomy code representing specimen collection required prior to the laboratory performing `CPT 81508`.
`76811`	Ultrasonic, pregnant uterus, real time with image documentation, fetal nuchal translucency measurement	Performed in first-trimester combined screening; nuchal translucency measurement is often integrated with `CPT 81508` results for final risk assessment.
`88360`	Immunohistochemistry or immunocytochemistry, per specimen; initial single antibody stain	Represents lab immunoassay methodologies conceptually similar to analyte testing though not used for `PAPP-A`/`hCG` specific immunoassays; included for workflow context.
`89250`	Routine cytogenetic analysis, prenatal sample	Used when abnormal screening results from `CPT 81508` prompt diagnostic testing such as chorionic villus sampling or amniocentesis with cytogenetic analysis.

CPT 81490: RA Disease Activity Score from 12-Serum Biomarker Panel

CPT-81493-CORONARY-ARTERY-DISEASE-23-GENE-RT-PCR-RISK-SCORE

CPT 81493: 23-Gene RT-PCR Test with Algorithmic CAD Risk Score

CPT-81500-CA125-HE4-ALGORITHMIC-RISK-SCORE

CPT 81500: CA-125 and HE4 Laboratory Testing with Algorithmic Risk Score

CPT-81503-ALGORITHMIC-LAB-RISK-SCORE-CA125-APOLIPOPROTEIN-A1

CPT 81503: Algorithmic Laboratory Risk Score Using Multiple Biomarkers

CPT-81504-TUMOR-ORIGIN-RNA-EXPRESSION-CLASSIFIER

CPT 81504: RNA Expression Tumor Origin Classifier

CPT-81506-DIABETES-BIOMARKER-PANEL-WITH-RISK-SCORE

CPT 81506: Diabetes Biomarker Panel with Algorithmic Risk Score

CPT-81507-NIPS-CELL-FREE-DNA-TRISOMY-RISK-ANALYSIS

CPT 81507: Non-Invasive Prenatal Screening for Trisomies 13, 18, 21

CPT-81509-LAB-ALGORITHMIC-RISK-ASSESSMENT-PAPP-A-HCG-DIA

CPT 81509: Laboratory Algorithmic Risk Assessment for PAPP–A, hCG, DIA

CPT-81510-PRENATAL-TRIPLE-MARKER-ALGORITHMIC-RISK-ASSESSMENT

CPT 81510: Prenatal Triple-Analyte Algorithmic Risk Assessment

CPT-81511-MULTIANALYTE-SERUM-SCREENING-ALGORITHMIC-RISK-SCORE

CPT 81511: Multianalyte Serum Screening with Algorithmic Risk Score

Showing 1–10 of 41

Frequently Asked Questions

References

1.CPT® Codes and Descriptions. AAPC. Retrieved Jul 29, 2026.
2.HCPCS Quarterly Update. Centers for Medicare & Medicaid Services (CMS). Retrieved Jul 29, 2026.
3.ICD-10-CM Full Code List. Centers for Medicare & Medicaid Services (CMS). Retrieved Jul 29, 2026.

Published by

Trek Health powers OpenPayer with a leading commercial payer intelligence platform, seamlessly converting fragmented payer data into actionable insights for provider organizations.

OpenPayer

CPT 81508: PAPP–A and hCG Laboratory Assay with Algorithmic Risk Score

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Billing Code Overview

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CPT 81508: PAPP–A and hCG Laboratory Assay with Algorithmic Risk Score

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Billing Code Overview

Clinical & Coding Specifications

Clinical Context

Coding Specifications

Related Diagnoses

Related CPT Codes

Related Codes

References

Clinical & Coding Specifications

Clinical Context

Coding Specifications

Related Diagnoses

Related CPT Codes

Related Codes

References

CPT 81508: PAPP–A and hCG Laboratory Assay with Algorithmic Risk Score

Sign up for cpt 81508 policy alerts

Billing Code Overview

CPT 81508: PAPP–A and hCG Laboratory Assay with Algorithmic Risk Score

Sign up for cpt 81508 policy alerts

Billing Code Overview

Clinical & Coding Specifications

Clinical Context

Coding Specifications

Related Diagnoses

Related CPT Codes

Related Codes

What clinical service does CPT 81508 describe and where is it typically performed?

Which billing modifiers are commonly used with CPT 81508 and when should they be applied?

How does CPT 81508 relate to other prenatal codes like venipuncture or nuchal translucency ultrasound?

What laboratory steps and reporting processes are described for services billed under CPT 81508?

Which payers are mentioned for CPT 81508 and does the page provide reimbursement rates or coverage decisions?

References

Clinical & Coding Specifications

Clinical Context

Coding Specifications

Related Diagnoses

Related CPT Codes

Related Codes

What clinical service does CPT 81508 describe and where is it typically performed?

Which billing modifiers are commonly used with CPT 81508 and when should they be applied?

How does CPT 81508 relate to other prenatal codes like venipuncture or nuchal translucency ultrasound?

What laboratory steps and reporting processes are described for services billed under CPT 81508?

Which payers are mentioned for CPT 81508 and does the page provide reimbursement rates or coverage decisions?

References