Summary & Overview
CPT 87337: Entamoeba histolytica Antigen Immunoassay
CPT code 87337 denotes an immunoassay laboratory test to detect antigens of Entamoeba histolytica, a parasitic cause of intestinal and extraintestinal infection. This code matters nationally because accurate antigen detection guides clinical diagnosis and public health responses to amoebic dysentery and related complications, and laboratory testing is a frequent component of infectious disease workflows. Payers commonly covering this service include Aetna, Blue Cross Blue Shield, Cigna Health, UnitedHealthcare, and Medicare. Readers will find a concise overview of the clinical purpose of the test, typical sites of service (clinical and hospital laboratories), and coverage context across major national payers. The analysis summarizes billing considerations, common modifiers used with lab services, and operational benchmarks where available. It also outlines clinical context for when antigen-based immunoassays are used versus alternative diagnostic methods, and highlights any recent policy or coding clarifications that affect billing and documentation. Data not available in the input is noted where applicable.
Billing Code Overview
CPT code 87337 describes a laboratory immunoassay performed by a lab analyst to detect antigens of the protozoan parasite Entamoeba histolytica. The procedure uses an immunoassay technique, such as enzyme immunoassay (EIA), to identify pathogen-specific antigens in a clinical specimen.
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Service type: Laboratory diagnostic test — antigen detection immunoassay
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Typical site of service: Clinical laboratory or hospital laboratory setting
Clinical & Coding Specifications
Clinical Context
A 28-year-old patient presents to an outpatient infectious disease clinic with acute-onset watery diarrhea after recent travel to an endemic area. The clinician collects a fresh stool specimen and orders an immunoassay for detection of Entamoeba histolytica antigen to confirm invasive amoebiasis versus nonpathogenic Entamoeba dispar. The specimen is transported to the hospital microbiology laboratory with proper labeling and chain-of-custody. A medical laboratory scientist or technologist performs the 87337 enzyme immunoassay (EIA) on the stool sample, documents specimen adequacy, runs appropriate positive and negative controls, interprets antigen presence/absence, and reports results in the electronic health record. Positive results prompt communication to the ordering provider for treatment planning and may trigger additional testing such as stool ova and parasite wet mount, stool PCR if available, or liver imaging if abscess is suspected. Typical sites of service include hospital outpatient laboratories, independent clinical laboratories, and hospital inpatient laboratories when testing is ordered during admission.
Coding Specifications
| Modifier | Description | When to Use |
|---|---|---|
26 | Professional component | Use when billing only the professional (interpretive) component separately from the technical component. |