Why it is performed
- Screen after an exposure, as part of sexual-health checks or during pregnancy.
- Investigate very recent infection when clinical indications justify PCR/NAT.
- Complete a diagnostic algorithm: a reactive screen needs supplemental testing before diagnosis is confirmed.
How it is performed
Venous blood is collected using single-use equipment and processed with the requested method. A reactive or inconclusive screen triggers the appropriate confirmatory pathway with a reference laboratory.
Preparation
- Give the exact date and type of the latest exposure and disclose PEP, PrEP or antiretroviral use.
- If exposure occurred less than 72 hours ago, seek urgent assessment for post-exposure prophylaxis rather than waiting for a test result.
- Do not stop PrEP or treatment on your own.
How Askabide processes it
Combined pathway
Routine laboratory screening simultaneously looks for p24 antigen and antibodies when a fourth-generation test is used. PCR/NAT detects viral genetic material and is reserved for specific indications. Askabide distinguishes local testing from mandatory external confirmation.
Part is performed at Askabide and another phase or confirmation is processed externally.
Results and indicative intervals
Intervals vary by method, analyser, reagent, units, age, sex, pregnancy, menstrual-cycle phase and reference population. The valid interval is the one printed on the laboratory report.
| Parameter or result | Indicative reference | How it is interpreted |
|---|---|---|
| Antigen/antibody: non-reactive | Cualitativo | No reactivity is detected, but the detection window must be considered according to date and test type. |
| Antigen/antibody: reactive | Requiere confirmación | It is not, by itself, a definitive diagnosis. |
| PCR/NAT: not detected | Cualitativo o cuantitativo | No viral RNA/DNA is detected above the assay limit; very recent exposure may still require repeat testing. |
| PCR/NAT: detected | Confirmación/valoración | Requires prompt clinical assessment and completion of the diagnostic algorithm. |
| Indeterminate/invalid | Repetición posible | A new sample or an alternative method may be required. |
Important limitations
- No test reliably detects every infection from day one; appropriate timing depends on assay and exposure.
- PEP, PrEP or very early treatment can alter marker dynamics.
- A reactive result must be communicated confidentially and confirmed through the appropriate algorithm.