Test Overview
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
Direct smear
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.
Urine sample
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.
Risks
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.
Results
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.
Gonorrhea test| Normal: | 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. |
|---|
| Abnormal: | 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.
References
Citations
- 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.
Credits
| By | Healthwise Staff |
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| Primary Medical Reviewer | Sarah Marshall, MD - Family Medicine |
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| Specialist Medical Reviewer | Peter Shalit, MD, PhD - Internal Medicine |
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| Last Revised | April 15, 2011 |
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