Final answer:
An inconclusive blood test for HIV is coded as R75 in the ICD-10-CM system, indicating inconclusive laboratory evidence of HIV. Follow-up testing is essential to determine the actual HIV status.
Step-by-step explanation:
When a patient has a blood test for HIV that returns as inconclusive, the appropriate ICD-10-CM code assignment would be R75, which indicates an inconclusive laboratory evidence of Human Immunodeficiency Virus [HIV].
It is important to follow up an inconclusive result with further testing, such as a PCR test or a repeat ELISA or Western blot, to confirm the presence or absence of HIV. If repeated testing confirms HIV infection, a new, more specific ICD-10-CM code should be used based on the stage and presence of any HIV-related illnesses.