A false-positive test means that a person was ‘accused of what he/she didn't do’ via a laboratory or diagnostic test result. More seriously, a false-positive test happens when a person tested positive for a disease he/she does not have.
STDs are perceived with no trace of happiness. It is bearable to read or hear about them from a distance, but quite depressing when you have to deal with them personally, especially with the ‘truthfulness’ of a result, albeit you are innocent all the while.
Truth be told, there's no perfect laboratory or diagnostic test. In most medical cases, doctors request for a retest or conduct another diagnosis on a patient before prescribing/describing drugs authoritatively.
Effects of false-positive test results on patients
A victim of a false-positive test result is likely to:
- Be very much anxious and worried (for nothing).
- Spend much more than bargained for on additional tests and retests.
- Get very angry (and relieved, hopefully) when it all turns out to be a joke.
- Sue the doctor or the health provider (could get quite messy).
How False-positive test results for STDs actually works
A Rapid Plasma Reagin (RPR) test is a blood test which screens for syphilis by detecting the antibodies produced by the body in response to the bacterium that causes syphilis. The test does not look for the bacterium, but for antibodies (proteins that fight off diseases) that may not be produced for syphilis alone, but for other diseases that demand the same antibodies.
The presence of another disease that produces the same antibodies as syphilis could give a false-positive test for syphilis. Few of the disease conditions that could cause a false-positive result for syphilis are HIV, Malaria, Lupus, and Lyme disease.
The Nucleic Acid Amplification Test (NAAT), though a standard diagnostic technique, has its specificity at less than 100%. This makes it prone to giving false-positive results, with no exception for gonorrhea. False-positive results for gonorrhea are more obtainable when people who are at a low risk of contracting the disease, or who live in areas where gonorrhea rates are very insignificant, are screened for gonorrhea.
The NAAT for testing chlamydia treatments is effective but could give a false-positive result by amplifying dead organisms, or by also giving signals for contaminants in the test container. Going for a retest for chlamydia soon after treatment is completed could yield a false-positive result for the already treated chlamydia patient.
One of the reasons the CDC (Centers for Disease Control and Prevention) does not recommend herpes testing for everyone is because of the likelihood of false-positive results for herpes. Only those that have symptoms for genital herpes are eligible to be tested for herpes. Persons who are at a low risk of having genital herpes can get false-positive results when screened. This can bring to the affected patient, worry, anxiety and depression.
Sniffing for a fishy odor and checking for abnormal coloration in vaginal discharge could be the most unreliable way of diagnosing bacterial vaginosis since bacterial vaginosis is not the only disease condition in women where there are abnormalities in the vaginal discharge.
Those aside, the Nugent Criteria has become infamous for giving false-positive results to women who do not have bacterial vaginosis. The Nugent Criteria has become limited to be used in places with no professional or specialized laboratory scientist.
Typically, an enzyme-linked immunosorbent assay (ELISA) is used by healthcare personnel to test for HIV. ELISA detects and measures antibodies for HIV in the blood. It is very possible for ELISA to measure other antibodies in the immune system, thereby giving a false-positive result. Relying on ELISA result alone could be quite deceptive, and may be very tragic for the recipient of the result.
Ways to minimize the occurrence of false-positive test results
- Focused testing is recommended for persons who tested positive falsely. Rather than check for antibodies alone, other criteria such as antiphospholipid antibodies detection should be in place (for syphilis).
- Routine testing for low-risk persons or persons from areas where an STD is not prevalent should be avoided.
- A patient’s sexual history should be obtained for assessment and interpretation of his/her test result.
- For chlamydial infection, it is advisable not to go for a retest so soon, after treatment.
- A follow-up test or a confirmatory test needs to be carried out, especially for HIV.
Though most STD test tools are very accurate, they could go wrong by a fraction. This explains why purchasing only approved ones from credible stores on or offline is important and could mean the difference between what is true or not.