Clarifying Coding for HIV and AIDS in ICD-10

Tune in to this monthly online coding column, facilitated by AHIMA’s coding experts, to learn about challenging areas and documentation opportunities for ICD-10-CM/PCS.

By Elena Miller, MPH, RHIA, CCS

While many people have heard the term “HIV” before, fewer are likely to know what it stands for: human immunodeficiency virus. This is the virus that causes acquired immunodeficiency sydrome, also known as AIDS. The difference in code assignment is based on whether or not the patient has the disease or if the patient is only a carrier of the virus. Do not get caught up on the terminology of “asymptomatic” vs. “symptomatic,” as many physicians do not utilize those terms when documenting HIV/AIDS. This terminology seems to be causing a great deal of confusion in ICD-10, even though it was also listed in ICD-9.

So what does it even mean? Asymptomatic and symptomatic actually refer to stages in the disease process. Coding professionals should not assume the stage based on “symptoms/conditions” documented or not documented in the record. The physician needs to specify the stage or document the cause and effect relationship with “symptoms/conditions” in the record.

So how are codes assigned for HIV and AIDS diagnoses?

B20 – Human immunodeficiency virus [HIV] disease

  • HIV disease
  • AIDS
  • AIDS – related complex [ARC]
  • AIDS – related conditions
  • HIV infection, symptomatic

Z21 – Asymptomatic human immunodeficiency virus [HIV] infection status

  • HIV infection
  • HIV positive
  • HIV
  • Known HIV
  • HIV virus
  • HIV status
  • HIV test positive
  • HIV infection, asymptomatic


Notice that both of the code descriptions include “human immunodeficiency virus [HIV],” but disease is only included in B20 and infection is only included in Z21. Take for example a case in which the physician documented “HIV disease” throughout the record, and the patient had been admitted for an unrelated reason. The coder feels that the HIV disease should code to Z21 because there were no symptoms mentioned in the record. The coder points out that there is an excludes note under B20 which excludes “asymptomatic human immunodeficiency virus [HIV] infection status.”

That rationale is incorrect. The code description for B20 is human immunodeficiency virus disease, therefore HIV disease is included in B20, according to the Official Guidelines for Coding and Reporting. That excludes note is specifically referring to a patient that has an asymptomatic HIV infection status, also known as HIV positive.

One of the major issues facing coders is that the patient’s condition is documented in a variety of ways within the same record. One day it will be HIV infection, the next will be HIV virus with a history of AIDS, etc. Conflicting documentation needs to be confirmed through a physician documentation clarification (PDC). When writing the PDC, do not include asymptomatic or symptomatic in the multiple choice options, unless the physician has used that terminology in the record. This terminology can be just as confusing for some physicians as it can for coding professionals. Take for example a physician who responds to a query with “asymptomatic HIV AIDS”.

A PDC written to clarify the status of disease should include the following options:

  • HIV positive status only
  • AIDS
  • Other
  • Clinically unable to determine


Please note that a “yes/no” query may be more appropriate depending on the documentation. For example, both HIV infection and oral thrush are documented in the record. It would be appropriate to send a yes/no query to establish a cause-and-effect relationship. Another example would be if the physicians are using HIV positive and AIDS interchangeably in the record. As both conditions are documented, it would be appropriate to use a yes/no query to resolve conflicting documentation between providers.

Elena Miller is director, coding audit and education, at Carolinas Healthcare System.


  1. This article demonstrates the difficulty that even the best coders have with how ICD-10-CM, their Guidelines, and the Coding Clinic have with HIV infections. The query above only gives the option of HIV positive status only and AIDS, ignoring many patients who have had symptomatic HIV infections (e.g. acute HIV syndrome, HIV-related lymphadenopathy, AIDS defining illness)in the past but who are asymptomatic today as a result of their HAART. If one reads the ICD-10-CM Official Guidelines carefully, should a patient EVER have a symptom due to a HIV infection, only B20 is coded and Z21 should NEVER be coded again…EVER! Unfortunately, the Coding Clinic makes the coder rely only on the documentation on the current encounter and AHIMA Query Practice Briefs prohibits me from using old records or coding advice as to query the provider in a manner that gets us the correct answer without playing 20 questions. In my opinion, if a provider documents +HIV or other similar language pointing to Z21, I am obligated to render the following query. Dear Dr. X. +HIV is documented in the record. If possible, please advise if this represents:
    1) HIV infection whereby the patient has never had any disease or symptoms due to HIV
    2) HIV disease whereby at some point the patient has had any disease or symptoms due to HIV, such as the acute HIV infection syndrome, lymphadenopathy, or an AIDS defining illness
    3) This is only a positive laboratory test – HIV infection has not been definitively diagnosed pending additional studies.
    4) This patient is not infected with HIV
    5) Other
    6) Cannot clinically determine – will be coded as asymptomatic HIV infection.

    I thank you for the privilege of contributing.

    Post a Reply
    • Dr. Kennedy,

      The query is intended to be very direct in asking the physician to document whether the patient has HIV infection only or AIDS. It is not intended to ignore patients that have had symptomatic HIV infections in the past. If the patient has had a symptomatic HIV infection, they should be diagnosed with AIDS and coded as such. The terminology asymptomatic vs. symptomatic was intentionally left out of the query as some physicians struggle to answer the question appropriately. Some physicians will answer “asymptomatic HIV” because the patient is currently without symptoms ignoring the fact that the patient has had a previous symptomatic/AIDS defining illness. The options that you provide are great and will be valuable to many coders that struggle with how to ask the question appropriately. Thank you for your contribution!

      Post a Reply
      • I agree with Dr. Kennedy that the first query example is not explanatory enough to help make the physicians aware of how difficult it is to code this condition without more input from them. If queries for +HIV were worded as Dr. Kennedy suggests, this would be educational as well as being more definitive for the coders to assign the code correctly. I have seen many examples of seeing B20 used in old encounters but the present encounter just states HIV Positive (even documentation by Infectious Disease specialty)causing continued queries every time the patient comes in, so perhaps the more detailed queries would eventually educate the physicians of coding requirements in a “not in your face” manner.

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    • Well said. Thank you for the excellent clarification. I will know in the future how to more effectively query the provider.

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  2. Dr. Kennedy, I need to point out something which I have to drill into providers heads daily. The use of the + sign. Coders cannot use + ____ and code the condition. We also cannot use up or down arrows or minus signs.. please be careful when placing examples in coding articles this just complicates things further. If a provider documents +HIV in your example it cannot be coded.

    Post a Reply
    • Incorrect. Coders CAN use + and -, but they CANNOT use up and down arrows.

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  3. Since many EMRs base their problem list drop down menus for diagnoses on the code book index, if our documentation indicates HIV disease, but pt has never had any AIDS related infections, and their CD4 count is high, we query for clarification.

    A diagnosis of AIDS has many implications outside of coding, such as insurance records, possible employment issues, etc. and we rather err on the side of caution

    Post a Reply
  4. I have a question if a patient walks in to the Emergency Department stating that he is suicidal but after a while he tells the Dr he has AIDS and not on any type of treatment. . The Dr diagnoses the patient as follows

    1. Oral Thrush
    2. Headache
    3. HIV+

    the Dr doesnt mention anywhere in the report the term AIDS or that the oral thrush is due to the HIV

    Would I code B20 as my principal dx ? Can I even code HIV since Dr states HIV+

    I initially did not pick up B20 I only coded thrush and other dx.. However I was told my coding was incorrect

    Post a Reply
    • 1. B37.0
      2. R51
      3. Z21

      Post a Reply
  5. How do you code HIV+ that has converted to full blown AIDS?

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  6. How do you code HIV on HAART?

    Post a Reply
  7. Hi,

    I have a question on Z21. In California by Law I can’t code the patient with HIV infection Z21, only code B20 if disease confirmed. is it right?


    Post a Reply
    • Yes, that is correct.

      Post a Reply
  8. From a clinical perspective, “disease” includes patients who are actively being treated. But for the medication treatment, the condition would progress. Similar to hypertension, the prescribing of medication is the treatment of a “disease.”

    Post a Reply
    • “Symptomatic” means any prior or current AIDS-defining condition (list called Appendix A available at CDC website). “Asymptomatic” means no AIDS-defining condition has occurred.

      All HIV+ patients with or without AIDS are treated. AIDS and HIV disease (or illness) are synonymous terms for those with current or prior Hx of (1)CD4+ T-lymphocyte count <200 -or- (2)an AIDS defining condition. HIV+ and HIV infection are synonymous terms for those who are HIV+ without AIDS (HIV disease). Treatment does not distinguish between HIV infection (HIV+ only) and HIV disease (AIDS).

      Post a Reply
  9. In claims data patients are frequently coded as ICD-9 042 or ICD-10 B20 when it appears the patient is not diagnosed with HIV. It appears that way because they were never on an antiretroviral regimen, may have been only on Truvada (PrEP) for years without another ARV, and may not have any other diagnoses consistent with HIV infection.

    Is the use of 042 or B20 ever correct among HIV-negative patients?

    Post a Reply
  10. Hi,

    If I may ask, has anyone had rejected Oasis due to the use of B20 in the first 6 diagnosis spots? We have had issues with the use of B20.

    Anyone have any ideas?

    Post a Reply

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