How to Read Your STD Test Results: Reactive, Not Detected, and Equivocal

Short answer: Most STI results use one of two word pairs. “Detected” and “not detected” usually come from tests that look for an infection’s genetic material. “Reactive” and “nonreactive” usually come from blood tests that look for antibodies or antigens. A positive or reactive screening result often needs a confirmatory test (HIV.gov, CDC), an uncertain result usually means you’ll be tested again (MedlinePlus), and “specimen rejected” means there’s no result at all.

This guide is about reading the words on the page. If you want to know how often tests are wrong and why timing matters, see can STI tests be wrong? This page won’t tell you whether you have an infection. Only a clinician who knows your history can do that.

Two families of result words

It helps to know what kind of test produced the result, because that decides which words you’ll see.

Chlamydia and gonorrhea are commonly tested on urine or a swab, often with nucleic acid tests (NAATs), so you may see “detected” or “not detected” as well as “positive” or “negative” (MedlinePlus). HIV, syphilis, herpes and hepatitis are usually blood tests, so you’re more likely to see “reactive” language and sometimes numbers.

A plain-language result glossary

Here’s what the common terms usually mean. Your lab’s exact wording may differ slightly, and the report or your clinician has the final word.

• Not detected / Negative: the test didn’t find what it was looking for in that sample. It doesn’t cover infections that weren’t tested, body sites that weren’t sampled, or exposures too recent to show up.
• Detected / Positive: the test found the infection’s genetic material. This usually leads to treatment through a clinician and, for some infections, a later retest.
• Nonreactive: no antibodies or antigens were found above the test’s cutoff. As with “not detected,” timing matters.
• Reactive: the test found antibodies or antigens above its cutoff. For HIV, HIV.gov explains that a positive antibody test needs a follow-up test to confirm it, and that a lab runs the follow-up on the same blood sample (HIV.gov). For syphilis, CDC says a reactive nontreponemal test should always be followed by a treponemal test (CDC). So a reactive line may be followed by more results.
• Preliminary positive: another way of saying a screening test was reactive and confirmation is pending.
• Equivocal / Indeterminate / Borderline: the result fell in a gray zone. It’s neither a yes nor a no. MedlinePlus notes that if you get an uncertain result, you’ll probably be tested again (MedlinePlus).
• Invalid: seen on rapid and self-tests. The test didn’t run properly, so it gives no answer. Follow the kit’s instructions, which usually means repeating with a new test.
• Pending / In process: the lab hasn’t finished. Some confirmatory tests take longer than the first screen, so one line can stay pending while others are back.

Numbers on the report: titers, index values and ranges

Some results come with numbers. Those numbers are read against the lab’s own reference range or cutoff, which is usually printed next to the result. MedlinePlus explains that labs often use different reference ranges and that results from different labs can’t be compared directly, so read your number against the range on your own report, not one you found online (MedlinePlus).

Three common examples:

• Titers look like a ratio, such as 1:8. They show how far the sample could be diluted and still react. CDC says nontreponemal syphilis tests (such as RPR) should be reported this way, and that a fourfold change, about two dilution steps, is the kind of difference that counts between two results on the same test (CDC). A positive syphilis screen also needs a second, different test to confirm it (MedlinePlus). Our guide to syphilis blood tests walks through how the different tests fit together.
• Index values are common on herpes antibody tests. A low positive can be hard to interpret. That’s covered in depth in herpes blood test results explained.
• Hepatitis markers come as a set of separate results, such as surface antigen and different antibodies, that are read together. Our hepatitis B and C testing guide explains which marker answers which question.

If a number confuses you, don’t try to translate it into a yes or no on your own. Ask the clinician or testing service what it means in your situation.

When there’s no result: rejected or insufficient samples

Sometimes the line on your report doesn’t give a result at all. You might see wording like “specimen rejected,” “QNS” (quantity not sufficient), “hemolyzed,” “leaked in transit,” “unlabeled” or “received outside stability.”

All of these mean the lab couldn’t run the test on that sample. That is not a negative. Common causes include too little blood or urine, a sample that sat too long before reaching the lab, or a tube that wasn’t labeled correctly.

The fix is a new sample. If you used a mail-in kit, contact the company about a replacement. Our guide to at-home kit collection mistakes covers the most common reasons samples fail and how to avoid them next time.

Check what was actually tested

A page full of “not detected” feels reassuring. Before you lean on it, check three things:

1. Which infections are listed. A standard panel may not include everything you assumed. Herpes, for example, isn’t always included automatically. See does a standard STI panel include herpes?
2. Which body sites were sampled. A urine test for chlamydia and gonorrhea checks the genitals. It doesn’t test the throat or rectum. If you had oral or anal sex, look for separate throat or rectal results. CDC’s screening recommendations include site-specific testing for some groups.
3. When the sample was collected. Every test has a window period. A result from a few days after an exposure may be too early to count. Our window periods guide shows when each test works best.

What to do next for each result

If your result is positive, our guide to what happens after a positive at-home STI test walks through confirmation, treatment and partners. A positive is the start of care, not a verdict.

If you need to retest after the window period and don’t want to wait for an appointment, a lab order is one option. Free options come first:

Affiliate link: we may earn a commission at no extra cost to you. Free options are listed above.

Reading results in a patient portal

Many patient portals release results as soon as the lab finishes, sometimes before anyone has reviewed them. That can mean seeing a confusing word late at night with no one to ask. A few habits help:

• Look for flags. Many portals mark results outside the reference range with an “H,” “L,” “A” (abnormal) or color. A flag tells you to ask, not what it means.
• Read every line. Confirmatory tests may appear as separate entries that load later.
• Save a copy. A screenshot or PDF with the test name, date and specimen type helps any future clinician.
• Send a message. It’s reasonable to write, “Can you tell me what this result means and whether I need to do anything?”

Testing is routine care, and so is asking what a result means. You don’t need to decode it alone.

Disclaimer: This article is for informational purposes only and does not diagnose, prescribe, or replace individualized medical care. Testing and treatment decisions should be made with a qualified healthcare provider. Some links on this page are affiliate links; we may earn a commission at no extra cost to you.