There is no single laboratory test that can diagnose all sexually transmitted diseases (STDs). Different tests help to diagnose different sexual diseases.

This post tells you how sexually transmitted diseases are diagnosed by various tests. It also tells you when and why screening for STDs should be done even when you do not have any signs and symptoms of any sexually transmitted disease.

Testing for STDs is done to diagnose the type of STD that you have in order to enable the correct treatment for a complete cure.

Screening is done in men and women who have been exposed to risk factors although they do not exhibit any symptoms. This is important given the dangerous complications that untreated STDs can cause.

Diagnostic tests for sexually transmitted diseases

  • Blood tests are done to diagnose the presence of HIV, hepatitis, and syphilis
  • Urine tests help diagnose gonorrhea and/or chlamydia
  • Swabs and fluid material are taken from local lesions and tested for the presence of STD microorganisms. A Pap smear is done in the case of females. Swabs may be taken from the mouth in case of oral infection, or from the urethra in males and from the cervix in case of females. This test helps in the diagnosis of chlamydia, gonorrhea, herpes, and HIV.

Why you should get tested?

As mentioned in STD statistics about one million people contract STDs every day worldwide. In the US there are about 20 million new STD cases every year, half of them being between the ages of 15 and 24 years. By the age of 25 years, about half of sexually active young people will get an STD in the US.

This is enough reason to get yourself tested because, though you may not have any STD symptoms, you could still be a victim of a silent sexually transmitted infection (STI). This is because many STD cases especially chlamydia and gonorrhea sometimes do not show any symptoms of the disease.

When are tests to diagnose STDs done?

  • To confirm the diagnosis made through any STD symptoms you may have
  • To confirm the cure, after the course of the STD treatment
  • To rule out the presence of mixed infections
  • To rule out sexually transmitted infection in a person of doubtful sexual exposure
  • To test your recent sex partner/s if you have tested positive.

Screening tests for sexually transmitted diseases and infections (STDs and STIs)

Screening is testing people in the general population who do not have any symptoms of STD or venereal diseases. It is done when the person himself or herself asks for it. Usually, it is not done routinely except during pregnancy.

If you want to be screened for STIs, you should interact with your doctor in detail and find out what STDs you are going to be tested for. Because of the cost factor, your doctor may not advise screening for sexually transmitted infections, if he feels you may not be having any.

Many a time, even when you contract a sexually transmitted infection, you may be asymptomatic. Screening for STDs will help you know whether you have a sexually transmitted infection.

The following tests are done to screen for STDs and STIs

  • Blood tests to diagnose the presence of HIV or syphilis
  • Urine test to diagnose the presence of gonorrhea or chlamydia
  • Swabs are taken from the mouth, urethra, or cervix and the rectum/ anus (if you have had anal sex), and the material is tested in the lab to detect any microorganisms that may be present. This may help to detect the presence of chlamydia, gonorrhea, herpes, or HIV.
  • A Pap smear is done in women over 30 years of age to detect precancerous or cancer of the cervix which can be caused by HPV.
  • Saliva is tested to detect HIV. This is the rapid HIV test with the results obtained on the same day.

When is screening advised?

  • If you are going in for a new relationship, get both of you screened.
  • Or otherwise, if you feel your partner could have been exposed to STD risk factors
  • If your partner has STD symptoms
  • If you are sexually active with multiple partners and without any symptoms
  • If you are planning to get pregnant and have a reason to suspect an STD infection.

Who should undergo screening tests for STIs?

Indications for STI screening tests are given below for the general population and are for those who have had sex previously.

  • HIV screening is advised for all after puberty who have had sex unprotected or protected.
  • All women after the age of 21 should have a pap smear done to rule out cervical infection and cervical cancer, which can be caused by certain strains of HPV (Human Papillomavirus). This should be done every three years. A Pap smear is a painless procedure that involves the collection of mucosal cells from the cervical opening of the uterus on a glass slide and examining the slide under a microscope for precancerous or cancerous cells.
  • Such women should also test for chlamydia and gonorrhea. This is done either by testing urine or vaginal secretions. If positive, the partner should also be screened for these STIs. It is advisable to test again after three months post-treatment to confirm complete recovery. The arrival of a new partner also requires retesting in a similar fashion.
  • Pregnant women are routinely tested during prenatal visits for HIV, hepatitis B and C, syphilis, gonorrhea, and chlamydia depending on their risk factors.
  • People who have HIV are more susceptible to catching other sexually transmitted infections. They should be tested for all bacterial and viral STIs – that means syphilis, gonorrhea, chlamydia, herpes, HPV, and hepatitis B and C. Women with HIV should undergo pap smear twice a year.
  • Homosexual men should also be tested twice a year for all STIs including HIV.