Can I get an STD blood test or do I need a swab?

Technician holding blood sample
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Question: Can I get an STD blood test or do I need a swab?

There are a number of reasons why people worry about going for an STD test. They may be concerned about the stigma associated with STDs. They may be worried about talking to their partner about STDs. They may also be afraid that going in for STD testing will require scary embarrassing or uncomfortable swabs

Fortunately, that last worry is reasonably easy to deal with.

Thanks to significant improvements in testing technology, many STDs can be detected via an STD blood test or urine test. Urine tests are primarily used to detect chlamydia and gonorrhea. However, there are a few more options for STD blood tests.

Answer: Commercial STD blood tests are widely available for the following sexually transmitted diseases.

  • Herpes: There are a number of herpes blood tests on the market. That said, their accuracy is somewhat variable.

    There is one very big downside  of herpes blood tests, other than the concern accuracy. That downside is that, since both HSV-1 and HSV-2 can infect either the mouth or the genitals, even the best type-specific herpes blood test will not tell you where you are infected in the absence of visible sores. They can only identify whether you are infected with HSV-1 or HSV-2. They can't tell you whether you have genital or oral herpes. 

    In addition, some doctors are reluctant to test for herpes in the absence of symptoms. They worry about the stigma associated with a positive test. They think that what people don't know won't hurt them. However, the virus can be transmitted even when no symptoms are present. That can lead to some painful conversations when a newly infected person thinks they've been lied to by the person they love. They may not believe that the person who infected them had no idea they had herpes. 
     
  • HIV: HIV is usually diagnosed through a blood test. There are also oral tests that use saliva samples to test for the virus that causes AIDS.

    In general, it requires both a positive initial test and a positive confirmatory test for a person to be considered HIV-positive. However, the process of confirmatory testing is usually invisible. Both tests are generally done on the same blood sample. When you get your results, it doesn't necessarily show what tests were done on your blood. It only shows what the test results were in combination
     
  • Syphilis: There are several different blood tests for syphilis. These are used in combination to determine both whether you are currently infected. They can also determine whether you have ever been infected in the past.
     
  • Hepatitis B: As with syphilis, there are multiple blood tests for Hepatitis. These can be used to determine your history of infection. They can also determine whether you're currently infected with the virus.
     

If neither a urine nor a blood test is available for an STD, then it is usually identified by either visual or microscopic examination of sores or by some form of bacterial culture. These types of tests may also be used instead of, or in addition to, blood tests for the diseases listed above in certain situations. For example, culturing of herpes sores can be a more effective way to detect the virus. That's not true in all situations, as timing of the testing is critical. But it can be a better choice if people visit their doctor early in an outbreak. 

Note: If you’re worried about a swab test and need one, talk to your doctor. It’s possible that you may be able to take the swab yourself. That won’t fix the problem for everyone. However self-swabs can be a big help for people who have histories of sexual trauma. They can also be helpful for people who are simply reluctant to have a stranger touch their body in what feels to them like an intimate way. Not all doctors will allow people to do self swabs, but they  have been shown to be effective for detecting many STDs. If nothing else, it’s better to have a self-swab test than no test at all.

Sources:

Blake DR, Maldeis N, Barnes MR, Hardick A, Quinn TC, Gaydos CA.Cost-effectiveness of screening strategies for Chlamydia trachomatis using cervical swabs, urine, and self-obtained vaginal swabs in a sexually transmitted disease clinic setting. Sex Transm Dis. 2008 Jul;35(7):649-55. doi: 10.1097/OLQ.0b013e31816ddb9a. 

Catarino R, Vassilakos P, Bilancioni A, Vanden Eynde M, Meyer-Hamme U, Menoud PA, Guerry F, Petignat P. Randomized Comparison of Two Vaginal Self-Sampling Methods for Human Papillomavirus Detection: Dry Swab versus FTA Cartridge. PLoS One. 2015 Dec 2;10(12):e0143644. doi: 10.1371/journal.pone.0143644.

Lunny C, Taylor D, Hoang L, Wong T, Gilbert M, Lester R, Krajden M, Ogilvie G. Self-Collected versus Clinician-Collected Sampling for Chlamydia and Gonorrhea Screening: A Systemic Review and Meta-Analysis. PLoS One. 2015 Jul 13;10(7):e0132776. doi: 10.1371/journal.pone.0132776.

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