False Positive Chlamydia Test: Why It Happens

A false positive chlamydia test can happen due to sample contamination, lab errors, or test kit issues. 

Some bacteria, like Mycoplasma or Ureaplasma, can cross-react with the test, leading to inaccurate results. 

If someone recently had chlamydia and got treated, leftover bacterial DNA might still be detected. Testing too soon after treatment can sometimes cause a false positive result. 

One study even found that some chlamydia strains have a genetic change that can make them invisible to certain tests, causing false-negative results.

Improper sample collection, like not following test instructions correctly, may also affect accuracy.

False negative chlamydia tests happen more often than false positives. Some studies suggest the false negative rate is 0%-28% in females and 0%-8% in males. 

Accuracy varies based on the testing method, but results are not always reliable. 

Retesting may be necessary, especially if symptoms continue despite a negative result.

Yes, some people may carry chlamydia and still test negative. The infection can sometimes stay in areas that routine tests do not check, such as the throat or rectum. 

Certain types of tests may be less sensitive, missing low bacterial levels in the body. In rare cases, chlamydia bacteria can enter a dormant state, making detection more difficult.

A urinary tract infection (UTI) might cause a false positive chlamydia test in some cases. Some UTI bacteria, like Escherichia coli, can interfere with test accuracy. 

A UTI can also cause inflammation and extra white blood cells, which might affect test results. 

If the urine sample is contaminated, the test could detect unrelated bacteria and give a false positive. Taking another test or using a different testing method can help confirm the results.

Read more: UTI vs Chlamydia: How to Tell Them Apart

A yeast infection does not usually cause a false positive chlamydia test. However, inflammation from a yeast infection may affect test accuracy. 

If vaginal discharge contaminates the sample, it might interfere with the results. 

Yeast infections can change cells and cause test errors. Taking samples the right way helps avoid false positives.

Read more: Chlamydia vs Yeast Infection: How to Diagnose and Treat

Chlamydia doesn’t directly cause a false positive herpes test.

But both infections activate the immune system, which can affect antibody tests. Some herpes tests detect old infections, which may cause confusion. If someone has both infections, results might be misread.

A more specific test can give a clearer answer.

Bacterial vaginosis (BV) can sometimes make a chlamydia test show a false positive.

BV changes the balance of bacteria in the vagina, which can affect test results. Some BV bacteria may confuse the test, leading to mistakes. 

BV can also cause inflammation, which might interfere with the sample.

If a test result seems wrong, retesting with a different method can help confirm it.

Pregnancy does not cause a false positive chlamydia test.

But hormonal changes can affect vaginal bacteria, which might interfere with results. More vaginal discharge during pregnancy can sometimes mix with the sample and cause errors. If the test isn’t done correctly, mistakes can happen.

Retesting can help make sure the result is accurate.