Pathology/Lab Coding Alert

Question: How do I know when to code for AIDS (B20), not HIV (Z21)?

Codify Subscriber

Answer: The distinction between ICD-10 codes B20 (Human immunodeficiency virus [HIV] disease) and Z21 (Asymptomatic human immunodeficiency virus [HIV] infection status) is based on whether the physician documents that the patient infected with HIV is symptomatic.

The physician might document a B20 diagnosis with terms such as acquired immune deficiency syndrome (AIDS), AIDS-related complex (ARC), or symptomatic HIV infection.

The physician may also document specific illnesses that indicate AIDS. The Centers for Disease Control and Prevention (CDC) maintains a list "AIDS defining illness," and if the physician documents HIV infection and one of those conditions, you should code B20.

Here's an abbreviated list from the CDC (you can access the entire list at www.cdc.gov/mmwr/preview/mmwrhtml/rr5710a2.htm):

• Candidiasis of bronchi, trachea, esophagus, or lungs
• Cervical cancer, invasive (patient 13 years or older)
• Coccidioidomycosis, disseminated or extrapulmonary
• Cryptococcosis, extrapulmonary
• Cryptosporidiosis, chronic intestinal (>1 month duration)
• Cytomegalovirus disease (other than liver, spleen, or nodes), age >1 month
• Encephalopathy, HIV related
• Herpes simplex: chronic ulcers (>1 month duration)
• Histoplasmosis, disseminated or extrapulmonary
• Isosporiasis, chronic intestinal (>1 month duration)
• Kaposi sarcoma
• Lymphoma, Burkitt (or equivalent term)
• Lymphoma, immunoblastic (or equivalent term)
• Lymphoma, primary, of brain
• Mycobacterium - certain specific listed conditions
• Pneumocystis jirovecii pneumonia
• Progressive multifocal leukoencephalopathy
• Salmonella septicemia, recurrent
• Toxoplasmosis of brain, onset at age >1 month

Never: Don't report B20 on the basis of an "HIV positive" lab test result. Without documented symptoms or AIDS-defining illness, you should stick to Z21 in those cases.

Once and always: If the patient has ever had an appropriately documented B20 diagnosis, you must henceforward assign B20, and never again assign Z21, even for an encounter with no current symptoms.