HIV Infections and Principal Diagnosis Selection

By Joanne Wilson, RN, ASN, CCDS, Senior Director, Solutions, Norwood

This article marks the beginning of a learning mini-series to address conditions commonly needing clarification for novice and expert CDI staff. We hope you enjoy them! Joanne welcomes your questions or comments at

The first topic in this miniseries is Human Immunodeficiency Disease (HIV) infections. The intent of this article isn’t an all-inclusive training but an effort to share common CDI tidbits and support CDI staff.

The FY 2024 ICD-10-CM Official Guidelines for Coding and Reporting, Section I.C.1.a. Human Immunodeficiency Disease (HIV) Infections provides clear guidance on when to assign the code B20 HIV versus code Z21 Asymptomatic HIV infection status.

The assignment of B20 does require confirmation of either HIV or an HIV-related illness; a practitioner(s) diagnostic statement is sufficient evidence.

The assignment of the code Z21 Asymptomatic HIV should be applied when the following occurs: no current or previous documentation of HIV symptoms/illness or if documentation includes common terminology such as “HIV positive” or “known HIV.” If necessary, query the provider if the documentation is unclear. Additionally, Z21 guidelines reference that if documentation includes AIDS or HIV disease, then code B20 would be assigned and not Z21.

The AHIMA/ACDIS Guidelines for Achieving a Compliant Query Practice Brief 2022 Update, starting on page 9, addresses the Role of Previous Encounters in Queries and what constitutes chart mining. The reference helps to clear up some confusion about when it is appropriate to review previous encounters.

The selection of the principal diagnosis (PDx) in the inpatient setting can cause even the most seasoned CDI reviewer to pause and research what occasion created the need for an inpatient admission.

The easiest way to ascertain the PDx is to ask yourself if the admission is related to an HIV diagnosis. If you can answer yes, typically, B20 is the first listed diagnosis.

If you answer no—for example the patient is being treated for a fractured hip—the PDx will be a hip fracture, and secondary code assignments would include B20 and any other HIV-related conditions.

Antiviral and prophylactic medications utilized in the management of HIV have separate guidelines and ICD-10 codes.

If you found this post helpful and have other topics on which you would like additional information, send me at email at The topic you submit might be the next in the mini-learning series.

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