Chapter 3 · Infection serology

HIV, hepatitis B, and hepatitis C serology must use methods with documented sensitivity and specificity data. Reactive HIV and HBsAg results must have a documented confirmation pathway. The laboratory must have a documented policy on result disclosure for confirmatory-reactive HIV results. Syphilis testing must follow a documented algorithm (EIA screening with TPPA/VDRL confirmation). All reactive infectious serology results must be reported with confirmation status documented.

Chapter 3 · Practical example

HIV reactive — confirming before communicating

A single reactive HIV screening result must never be communicated as HIV positive. A confirmation algorithm must be completed before any interpretive result is reported.

▲ The situation

A fourth-generation HIV Ag/Ab combination test is reactive on a sample from a patient attending a GUM clinic. A clinic nurse calls the laboratory asking for the result.

Reference: ISO 15189:2022 Clause 7.8; BHIVA HIV Testing Guidelines

✓
Good practice

The scientist explains that the screen is reactive and that per the laboratory’s documented HIV testing algorithm, a confirmatory HIV-1/HIV-2 differentiation immunoassay is performed on the same sample before any interpretation is communicated. The confirmation is positive for HIV-1. The report: HIV Ag/Ab screen reactive. Confirmed HIV-1 reactive on differentiation immunoassay. Consistent with HIV-1 infection. Viral load and CD4 count recommended. This report goes to the clinician through the clinical channel — not verbally to the nurse.

✗
Poor practice

The scientist tells the nurse the HIV screen is positive. The nurse returns to the consulting room and informs the patient. Two days later, the confirmation assay is non-reactive — the screening result was a false positive. The patient has been incorrectly told they have HIV. The psychological impact is significant and the laboratory faces a formal complaint.

● What this means for your practice

HIV reactive screen results must never be communicated as a diagnosis before confirmation. The reporting pathway — who receives the result, in what format, at what stage of the algorithm — must be documented and followed without exception. This protects the patient from the consequences of a false positive screen.