Measurement of HIV antibodies and antigens in a blood sample; a definitive diagnosis is established by a confirmatory test after a positive screening.
Indication
- Unexplained fever, weight loss, night sweats, or chronic diarrhea
- Recurrent oral thrush, herpes zoster (shingles), or opportunistic infections
- Suspicious exposure after unprotected sexual intercourse
- History of intravenous drug use or needle sharing
- Screening before or during pregnancy
- Evaluation of healthcare workers after a needlestick injury
- Unexplained lymphadenopathy (enlarged lymph nodes) or pancytopenia
Preparation
- No special fasting is required
- The date of suspicious exposure and risk factors should be reported to the laboratory
- Pre- and post-test counseling is recommended
- Confidentiality of results is protected by law
How it's performed
- A 5-10 mL blood sample is drawn from a vein in the arm
- The 4th-generation HIV ELISA test measures the p24 antigen and HIV-1/HIV-2 antibodies together
- Positive or equivocal results are confirmed by Western blot or HIV RNA (PCR)
- Tests may need to be repeated within the window period (3 months)
- Results are evaluated confidentially by the physician
Post-procedure
- If the result is negative and the exposure is suspicious, repeat testing after 3 months is recommended
- Confirmed positive results are referred to an infectious diseases specialist
- CD4 count, viral load measurement, and resistance testing are planned
- Antiretroviral therapy (ART) is initiated and regularly followed by a specialist physician
- Informing and screening of partners and close contacts is important
Risks
- Pain, bruising, or hematoma at the blood draw site
- Rare fainting (vasovagal reaction)
- Possibility of a false-negative result during the window period
- False-positive result (rare; a confirmatory test is always performed)
- Psychological stress related to the test result (counseling is recommended)
FAQ
When should I be tested after a suspicious exposure?
With 4th-generation tests, early diagnosis is possible after 4-6 weeks; however, a repeat test at 3 months is recommended for a definitive result.
What does a positive HIV test mean?
A positive screening test requires confirmation. A definitive diagnosis is established with Western blot or HIV RNA testing. Confirmed HIV infection is today a chronic condition that can be managed with regular treatment.
Are the results confidential?
Yes, HIV test results are legally confidential and are shared only between the patient and the responsible physician.
Do I need to be fasting for the test?
No, fasting is not required. The test can be performed at any time of day.
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