Short answer
Reactive = the assay detected its target above threshold.
Nonreactive = it did not.
Neither word diagnoses: reactives need confirmatory ladders plus clinical interpretation before becoming diagnoses, and nonreactives need window, site, and technique review before becoming clearance.
Laboratories choose this vocabulary deliberately, measurement honesty over diagnostic overreach, and reading results literally (signal language, not verdict language) prevents most result misinterpretations.
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See Tests & Prices →What each triggers
| Result | Immediate meaning | Required next step |
|---|---|---|
| Reactive | Signal detected | Confirmatory ladder + clinical interpretation |
| Nonreactive, proper timing/sites | Likely clear | File, maintain cadence |
| Nonreactive, early/narrow | Provisional | Scheduled retesting |
| Indeterminate/equivocal | Borderline signal | Interval repeat, possibly new method |
Reading companion: Understanding Your STI Results: Next Steps.
Report literacy: How to Read a Laboratory STI Report.
Interpretation principles
- Signals become diagnoses only through confirmatory sequences and clinical context.
- Timing and coverage qualify every nonreactive. Chemistry cannot vouch for untested windows or sites.
- Titer values add dimension where reported. Trends across draws outweigh single snapshots.
- Questions route to ordering clinicians first. They hold the full clinical picture labs never see.
Confirmatory cascades in practice
Reactive results trigger organism-specific cascades worth understanding in advance: syphilis reactives enter reverse-or-traditional algorithm completion with titer staging; HIV reactives enter differentiation-then-NAT ladders; herpes low-positive reactives route to different-method confirmation; NAAT reactives generally stand with clinical correlation plus window review.
Each cascade reflects decades of error-pattern evidence encoded into protocol.
Cascade participation responsibilities: keep every appointment in sequence (dropped rungs strand interpretation), avoid parallel freelance testing that confuses adjudication, disclose full histories enabling pattern recognition, and protect partners through resolution regardless of impatience.
Cascades complete fastest with compliant participants and stall with improvising ones.
Trust designed sequences over instincts.
When to seek care
Now if a result is positive or indeterminate. Confirmatory and treatment pathways start immediately, not after deliberation.
On schedule for window-based rechecks, and promptly for any symptom contradicting paperwork.