Summary & Overview
CPT 87335: E. coli O157 Antigen Immunoassay
CPT code 87335 denotes an immunoassay performed to detect antigens of Escherichia coli O157, a clinically important pathogen associated with gastroenteritis and potential complications. Nationally, antigen testing for E. coli O157 supports timely diagnosis, infection control, and appropriate clinical management, making this code relevant across outpatient and inpatient laboratory settings. Key payers addressed in this analysis include Aetna, Blue Cross Blue Shield, Cigna Health, UnitedHealthcare, and Medicare.
Readers will find a concise overview of clinical context for antigen-based E. coli O157 testing, typical sites of service, and the role of immunoassays such as EIA in laboratory diagnosis. The publication summarizes reimbursement benchmarks and payer coverage patterns where available, highlights recent policy or coding updates affecting laboratory billing for antigen detection, and outlines common billing considerations for claims processing. Where input data is incomplete, the report indicates that specific items are not available in the input. The content is intended for a national audience of billing professionals, laboratory managers, and policy analysts seeking a practical reference for CPT code 87335 and its use in diagnostic microbiology workflows.
Billing Code Overview
CPT code 87335 identifies an immunoassay test to detect Escherichia coli O157 antigens, typically performed by a laboratory analyst using techniques such as enzyme immunoassay (EIA). This test detects bacterial antigens in patient specimens to support diagnosis of E. coli O157 infection.
Service Type: Laboratory diagnostic test, infectious disease serology/antigen detection
Typical Site of Service: Clinical laboratory or hospital laboratory
Clinical & Coding Specifications
Clinical Context
A 7-year-old child presents to the urgent care clinic with acute onset of severe abdominal pain, watery diarrhea, and visible blood in the stool following attendance at a community picnic 48 hours earlier. The clinician performs a history and focused abdominal exam, documents signs of dehydration and fever, and orders stool testing for enteric pathogens. A stool specimen is collected and sent to the laboratory for an immunoassay to detect Escherichia coli O157 antigen using CPT 87335. The laboratory technician logs the specimen, performs the enzyme immunoassay (EIA) per manufacturer protocol, interprets the result, records quality controls, and reports a positive result to the ordering provider and local public health authorities according to reportable disease rules. The ordering clinician uses the result to guide clinical management (fluid support, avoidance of antibiotics for suspected E. coli O157 when clinically appropriate) and documents the test, result, and public health notification in the medical record.
Coding Specifications
| Modifier | Description | When to Use |
|---|---|---|
11 | Office or other outpatient visit | Use when the test is ordered as part of a standard outpatient visit and billed by the performing provider. |
26 |