Sexually Transmitted Infection (STI) Tests

What are STI tests?

STIs (sexually transmitted infections) or sexually transmitted diseases (STDs) are infections that are passed from one person to another through sexual contact. STIs are usually spread during vaginal, oral, or anal sex. But sometimes, they can spread through other sexual contact involving the penis, vagina, mouth, or anus. This is because some STIs, like herpes and HPV (human papillomavirus), are spread by skin-to-skin contact.

Other ways that some STIs may be spread include:

• Through close personal contact, such as kissing
• From a pregnant person to their baby during pregnancy or when giving birth
• During breastfeeding
• Through blood transfusions
• By sharing needles

Certain bacteria, viruses, and parasites cause STIs. Millions of Americans get an STI every year, and many of those infections are in teens and young adults. Common STIs include chlamydia, gonorrhea, genital herpes, HIV, and HPV infection.

Left untreated, certain STIs can cause long-term health problems such as blindness, brain damage, infertility, birth defects, and even death. Fortunately, all STIs can be treated, and some can be cured. However, that doesn't prevent you from getting infected again if you don't take steps to prevent infection. STI testing can help you get diagnosed and treated so you may avoid serious complications.

Other names: STD screening, STI (sexually transmitted infection) tests, STI screening, STD testing

What are they used for?

STI tests are used to find out if you have been infected with an STI. Testing can help you get the treatment you need and may help prevent the spread of infection.

Why do I need an STI test?

STIs don't always cause symptoms, so catching or spreading an infection is possible even if you or your partner seem healthy. That's why STI screening tests are important. They look for diseases before you have symptoms.

Anyone who is sexually active could get an STI. So talk to your health care provider about your risk for HIV and other STIs and whether you need to be tested. If you are sexually active, you might consider getting a yearly test for HIV. Other STI testing is mostly recommended for people who are at higher risk for certain STIs:

• Sexually active women under the age of 25. Experts recommend that women in this age group get a chlamydia test and a gonorrhea test every year. Sexually active women 25 years and older should be tested if they have new or multiple sex partners or have a partner who has been diagnosed with an STI.
• Women 21 to 30 years old. Women in this age group should get a Pap smear to check for cell changes in the cervix that could become cancer if not treated. These can be caused by HPV (human papillomavirus).
• Women 30 years and older. Women in this age group should talk to their provider about whether to get a Pap smear, HPV test, or both.
• Pregnant people. Pregnant people are usually tested for HIV, hepatitis B, chlamydia, and syphilis. If you are pregnant and have certain risk factors, you may also be tested for gonorrhea and hepatitis C.
• Sexually active men and women who have unprotected sex (sex without a condom) and have more than one sexual partner. They should be tested regularly for HIV and other STIs as recommended by their provider.
• Men who have sex with men. Compared with other groups, men who have sex with men and bisexual men have a higher risk of STIs. Men in this group should be tested at least once a year for syphilis, chlamydia, gonorrhea, and HIV. Men with multiple partners may benefit from more frequent testing.
• People with HIV. If you have HIV, you are at higher risk of getting another STI. People in this group should be tested for syphilis, gonorrhea, and herpes. A chlamydia test is also usually recommended.
• People who use injectable drugs. Sharing needles puts you at risk for HIV. Regular HIV testing is recommended for this group.

Some STIs do not cause symptoms or may only cause mild symptoms. So it is possible to have an infection and not know it. Symptoms vary depending on the type of STI, but you may need testing if you have one or more of the following symptoms:

• Painful or frequent urination (peeing)
• Pain during sex
• Unusual odor in vaginal discharge
• Vaginal itching
• Discharge and/or itching from the penis
• Sores or bumps in the genital or rectal area
• Blisters or sores in or around the mouth
• Anal itching, soreness, or bleeding

Even without symptoms, STIs can still be harmful and may be passed on to your partner during sex.

What happens during an STI test?

Some STIs may be diagnosed during a physical exam, blood tests, or a microscopic examination of a sore or fluid swabbed from the vagina, penis, or anus. Depending on the type of suspected infection, you may get one of the following types of tests:

Blood tests

• Used to diagnose syphilis, HIV, hepatitis B, and sometimes herpes.
• During the test, a health care professional will take a blood sample from a vein in your arm, using a small needle. After the needle is inserted, a small amount of blood will be collected into a test tube or vial.

Urine tests

• Used to diagnose trichomoniasis, chlamydia, and sometimes gonorrhea.
• During the test, you will provide a sterile sample of urine in a cup as instructed by your provider.

Swab tests

• Used to diagnose HPV, chlamydia, gonorrhea, and herpes.
• During the test, a provider will use a special swab to take a sample from the site of the infection. In women, samples may be taken from the vagina or cervix. In men, samples may be taken from the penis or urethra, the tube that carries urine out of the body.

Lumbar puncture, also known as a spinal tap

• This is not a frequently used STI test, but it may be ordered if your provider thinks you have an advanced stage of syphilis or if a herpes infection has affected your brain or spinal cord.
• For this test, a provider will inject an anesthetic into your back so you won't feel any pain during the procedure.
• Once the area is numb, the provider will insert a thin, hollow needle between two vertebrae in your lower spine. Vertebrae are the small bones that make up your spine. Your provider will then withdraw a small amount of fluid for testing.

You may also be able to check for STIs with an at-home test. Home test kits are available for several STIs, including chlamydia, gonorrhea, syphilis, trichomoniasis, and hepatitis C.

• These tests usually involve using a device (lancet) to prick your finger for a drop of blood, collecting a urine sample, or taking an oral swab. You should discuss your at-home STI test results with your provider to see if you need further testing and/or treatment.

Will I need to do anything to prepare for the test?

You don't need any special preparations for a blood test. Women may need to avoid douches and vaginal creams for 24 hours before a urine or swab test.

You may need to empty your bladder before a lumbar puncture.

Your provider will let you know if you need other preparations.

Are there any risks to the test?

There is very little risk to having a blood test. You may have slight pain or bruising at the spot where the needle was put in, but most symptoms go away quickly.

There are no known risks to having urine or swab tests.

If you had a lumbar puncture, you may have pain or tenderness in your back where the needle was inserted. You may also get a headache after the procedure. The headache can last for several hours or up to a week or more, but your provider may suggest treatment to relieve the pain.

What do the results mean?

The test result will show whether you have an STI.

If you have an STI, be sure to take the medicine as prescribed by your provider. It's also very important that you tell your partner so they can get tested and treated if necessary. Some types of STIs can cause serious health problems if they are not treated.

Learn more about laboratory tests, reference ranges, and understanding results.

Is there anything else I need to know about STI tests?

You can take steps to help protect yourself from STIs. The only way to completely prevent them is by not having sex. But if you do decide to have sex, you can lower your risk of getting an STI by:

• Having you and your partner tested for STIs before having sex.
• Reducing your number of sex partners.
• Being in a long-term relationship with "mutual monogamy" with just one partner who has tested negative for STIs. This means that you agree to be sexually active only with them, and they agree to be sexually active only with you.
• Using latex condoms correctly every time you have sex. Correct use of condoms greatly reduces but does not eliminate, the risk of catching or spreading STIs. If you or your partner is allergic to latex, you can use polyurethane condoms.
• Getting vaccinated against HPV and hepatitis B.