Gonorrhea tests involve testing a sample of body fluid or urine to see if gonorrhea bacteria (Neisseria gonorrhoeae) are present and may be the cause of an infection. These tests are used to screen for or confirm a gonorrhea infection.
Gonorrhea is a sexually transmitted infection (STI) that is usually spread during sexual contact. It does not always cause symptoms.
Several types of tests can be used to detect a gonorrhea infection. Most tests use a sample of body fluid from the affected area.
- Nucleic acid amplification tests (NAAT). NAATs detect and make many copies of the genetic material (DNA) of gonorrhea bacteria. NAATs include polymerase chain reactions (PCRs) and transcription mediated amplification (TMA). These tests are very accurate and can be done either on a urine specimen or a sample of body fluid from the potentially infected area.
- Nucleic acid hybridization test (DNA probe test, molecular probe test). Molecular probe testing detects genetic material (DNA) of gonorrhea bacteria. This test is done on the body fluid collected from the potentially infected area, most often the cervix or urethra. Samples collected from the throat do not always provide accurate test results. Often the molecular probe test for gonorrhea also tests for chlamydia, another STI with symptoms similar to those caused by gonorrhea.
- Gonorrhea culture. A gonorrhea culture is done on a sample of body fluid collected from the potentially infected area, such as the cervix, urethra, eye, rectum, or throat. The sample is combined with substances that promote the growth of gonorrhea bacteria. Unlike other gonorrhea tests, a culture can determine if gonorrhea bacteria are resistant to certain antibiotics.
- Gram stain. A Gram stain test is done on a sample of fluid from the penis or, less commonly, the cervix. The fluid is spread on a microscope slide and stained with a dye that can help identify gonorrhea bacteria. A Gram stain is less reliable than a culture or molecular probe test for detecting gonorrhea, but it produces faster results. Gram stain testing done on a sample from the cervix is not very accurate.
- Enzyme-linked immunosorbent assay (ELISA, EIA). EIA testing is done on a sample of fluid from the penis or cervix. An EIA test detects substances that trigger the immune system to fight the gonorrhea infection (gonorrhea antigens). An EIA test is less accurate for detecting gonorrhea than a gonorrhea culture.
Why It Is Done
Tests for gonorrhea are done to:
- See if a gonorrhea infection may be causing symptoms such as painful urination, anal itching or bleeding, vaginal bleeding after intercourse, or abnormal discharge from the penis or vagina.
- Screen women who are at high risk for a gonorrhea infection. Because a gonorrhea infection does not always cause symptoms, screening is important. The United States Preventive Services Task Force (USPSTF) recommends routine gonorrhea screening for:1
- Check for infection in a newborn whose mother had gonorrhea at the time of delivery.
Treating a pregnant woman who has a gonorrhea infection can prevent an infection in her newborn. Screening may be done at the first prenatal visit. Another test may be done during the last 3 months of pregnancy.
In some cases, gonorrhea tests may be done to determine if a recently treated infection has been successfully treated. This is not routinely needed unless gonorrhea has occurred during pregnancy or your sex partner was not treated.
How To Prepare
Gonorrhea testing is done on:
- Fluid collected from the area of the body that is likely to be infected. Women should not douche or use vaginal creams or medicines for at least 24 hours before having a gonorrhea test.
- Urine. Do not urinate for 2 hours before a urine sample is collected.
How It Is Done
In a direct smear, a sample of body fluid is taken from the affected area. In adults, these areas may include the urethra, cervix, rectum, or eye.
- To collect a sample from the urethra or rectum, your health professional will insert a swab into the opening of your urethra or rectum to collect a sample.
- To collect a sample from the cervix, you will be asked to take off your clothes below the waist and drape a paper or cloth covering around your waist. You will then lie on your back on an examination table with your feet raised and supported by stirrups. This allows your health professional to examine your vagina and genital area. Your health professional will insert an instrument with curved sides (speculum) into your vagina. The speculum gently spreads apart the vaginal walls so the inside of the vagina and the cervix can be examined. Samples are collected from the cervix with a swab or small brush.
- To collect a sample from your eye, your health professional will gently brush the insides of your lower and upper eyelids with a swab.
In rare cases, a throat culture may be done.
If a urine sample is collected for nucleic acid amplification testing (such as PCR or LCR testing), do not urinate for 2 hours before the test. Do not wipe the genital area clean before urinating. Collect the first part of your urine stream, immediately as you begin urinating.
How It Feels
Collecting a sample of fluid from the urethra, anus, or rectum may cause mild discomfort or pain.
Collecting a sample from the cervix may cause mild discomfort. Most women find that the procedure feels similar to a Pap test or pelvic examination. Some women feel slight cramping while the speculum is inside the vagina.
Collecting a sample from the eye is usually painless unless the eyelids have sores on them.
Collecting a urine sample does not normally cause any discomfort.
There is very little risk of serious complications from having a sample of fluid collected from the cervix, urethra, anus, eye, or throat. Women may have a small amount of bleeding from the vagina if a sample is collected from the cervix.
In rare cases, a person may experience a sudden dizziness or fainting (called vasovagal syncope) because of fear or pain when the swab is inserted into the urethra.
There are no risks linked with collecting a urine sample.
Gonorrhea tests involve testing a sample of body fluid or urine to see if gonorrhea bacteria (Neisseria gonorrhoeae) are present and may be the cause of an infection.
No gonorrhea antigens or DNA are found. If a culture is done, no gonorrhea bacteria grow in the culture. More testing for other sexually transmitted infections (STIs) may be needed to determine the cause of any symptoms.
Gonorrhea antigens or DNA are found. If a culture is done, gonorrhea bacteria grow in the culture.
What Affects the Test
Reasons you may not be able to have the test or why the results may not be helpful include:
- Urinating within 2 hours of collecting a urine sample.
- Contamination of a rectal sample with stool.
- In women, douching or using vaginal creams or sprays within 24 hours of the test.
- The use of antibiotics before the test.
What To Think About
- If a gonorrhea infection is suspected, avoid sexual intercourse until the test results have come back. If results point to a gonorrhea infection, continue to avoid sexual intercourse for 7 days after the start of treatment. Your sex partner must also be treated for a gonorrhea infection to avoid reinfecting you or to avoid infecting others.
- If you have a gonorrhea infection, all of your sex partners from within the last 60 days should be tested and treated. If gonorrhea is suspected, you may need to have tests for other sexually transmitted infections, including HIV infection.
- Only one laboratory test (ELISA, DFA, PCR, DNA probe testing, or gonorrhea culture) is needed to diagnose gonorrhea. Your health professional usually chooses which test to use.
- Samples for gonorrhea testing may be taken from more than one site.
- The nucleic acid amplification tests (NAATs) are more accurate than a gonorrhea culture because they can detect both living and dead gonorrhea bacteria. The NAATs are more expensive than a gonorrhea culture or Gram stain.
- A gonorrhea culture may be done after a positive nucleic acid amplification test (NAAT) or nucleic acid hybridization test (DNA probe test) if your health professional is concerned that you may have antibiotic-resistant gonorrhea.
- In the United States, your health professional must report to the state health department that you have gonorrhea.
- For more information on the treatment for a gonorrhea infection, see the topic Gonorrhea.
U.S. Preventive Services Task Force (2005). Screening for gonorrhea. Available online: http://www.uspreventiveservicetaskforce.org/uspstf/uspsgono.htm.
Other Works Consulted
Chernecky CC, Berger BJ (2008). Laboratory Tests and Diagnostic Procedures, 5th ed. St. Louis: Saunders.
Fischbach FT, Dunning MB III, eds. (2009). Manual of Laboratory and Diagnostic Tests, 8th ed. Philadelphia: Lippincott Williams and Wilkins.
|Primary Medical Reviewer||Sarah Marshall, MD - Family Medicine|
|Specialist Medical Reviewer||Peter Shalit, MD, PhD - Internal Medicine|
|Last Revised||April 15, 2011|