Can STD Tests Be Wrong? (2024)

Can STD Tests Be Wrong?

Dr. Leonard Leng of ATA Medical Singapore.
Authored By: Dr. Leonard Leng.
Last updated: 27 Aug 2024.
Positive STD test results.

While sexually transmitted disease (STD) tests are designed to be highly accurate, they are not infallible. STDs, such as chlamydia, gonorrhoea, syphilis, HIV, and herpes, are infections primarily spread through sexual contact. STD tests are essential for diagnosing these infections, as the only way to know for sure if you are infected is through testing. However, errors can occur, resulting in inaccurate test results. Understanding the potential for inaccuracies is important when interpreting test results to take appropriate steps for your health.

Top 5 sexually transmitted infections STI in Singapore (2018).
Source: National Skin Centre

According to the National Skin Centre, in 2018, the top five STIs constituted 8,024 reported cases in Singapore. STD testing is nonetheless vital for early detection and timely treatment, and preventing transmission to others.

Types of STD Tests

Common types of STD tests that are typically performed on either blood, urine, or swab (throat, genital area, rectum) samples include:

  • Antibody Tests: These tests detect antibodies, which are proteins produced by your immune system to fight off infections. They are commonly used for diagnosing HIV, syphilis, and hepatitis B and C.
  • Antigen Tests: These tests detect specific proteins (antigens) from the virus or bacteria. They are used for infections such as HIV and syphilis.
  • Nucleic Acid Amplification Tests (NAATs): These tests detect the genetic material (DNA & RNA) of bacteria or viruses. They are used for diagnosing infections such as chlamydia, gonorrhoea, and trichomoniasis.
  • DNA Tests: These detect the DNA of certain viruses, such as human papillomavirus (HPV).
  • Viral Culture: This test involves growing a sample of the virus in a laboratory to confirm its presence. It is often used for diagnosing herpes.
Viral culture STD test.

Understanding Test Accuracy

Two key measures of test accuracy are sensitivity and specificity:

  • Sensitivity: The ability of a test to correctly identify those with the infection. High sensitivity reduces the chance of false negatives, where an infected person is incorrectly identified as not having the infection.
  • Specificity: The ability of a test to correctly identify those without the infection. High specificity reduces the chance of false positives, where a person is incorrectly identified as having the infection when they do not.

You can talk to your doctor to find out more about the various tests used for STD screening to make an informed decision.

Factors Affecting Test Results

  • Type of STD Being Tested for: Different STDs require different testing methods, and the accuracy can vary.
  • Timing of Tests: Testing too soon after exposure can lead to false negatives because the infection may not have reached detectable levels. Each STD has a window period, which is the time between exposure and when the test can reliably detect the infection.
  • Sample Collection & Handling: Proper collection, storage, and handling of samples are essential for accurate results.
STD swab test.

Interpreting Results

After receiving your results, it is crucial to consult with your doctor to determine if follow-up confirmatory testing is required and, if necessary, to develop an appropriate treatment plan to prevent further health complications. Understanding the limitations of STD tests and seeking professional medical advice ensures that you receive appropriate care.

Summary

Despite not being infallible, STD tests are absolutely essential for diagnosis and treatment, to prevent further health complications and transmission to others. Being aware and understanding the potential for inaccurate results underscores the importance of seeking professional medical advice in interpreting such tests and determining further steps for your health and well-being. If you are unsure of which STD tests are suitable for you, schedule an appointment with a doctor to discuss more.

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Frequently Asked Questions (FAQs)

False STD tests are uncommon but can occur, with false negatives more frequent than false positives, especially if testing is done too soon after exposure.
Yes, you can test negative and still have an STD, especially if the test is done during the window period. Retesting is recommended after the window period.
STD tests are generally highly accurate but no test is 100% infallible.
Yes, STD blood tests can be wrong due to various factors. Follow-up testing can help confirm results.
Yes, STDs can be misdiagnosed due to false positives, false negatives, or overlapping symptoms with other conditions.
No, STI tests are not 100% accurate. They are highly reliable but can still produce false positives or false negatives.
No, two uninfected partners cannot contract an STD from each other. However, undiagnosed infections from previous exposures can be transmitted.
Yes, STDs can be contracted from past partners, non-sexual routes like shared needles, or mother-to-child transmission during childbirth.
HPV and herpes can be hard to detect due to a lack of symptoms and periods of dormancy. Specific tests are required for diagnosis.
Yes, STDs can go undetected, especially if tested during the window period or if the infection is latent. False negatives can also occur.
Urine tests are highly accurate for chlamydia and gonorrhoea but less suitable for other STDs that require blood tests or swabs.
Incorrect STD test results are rare but possible. False positives and negatives can happen due to test timing, sample collection, or test sensitivity.
STI symptoms can appear within days to weeks for some infections like gonorrhoea, but others may take months to years.
You might have another condition, tested too early, or there could be a testing error. Retesting and consulting your doctor is strongly advised.