Testing to diagnose gonorrhea in men and women gathers importance in view of the fact that 10% of the infected males and 80% of the infected females are asymptomatic (without symptoms).

In the U.S., 46% of gonorrhea patients between the ages of 14 to 39 years also have another sexually transmitted disease called Chlamydia.

All patients with gonorrhea symptoms and complications should therefore be also tested for Chlamydia.

HIV is another sexually transmitted disease (STD) that should also be tested for, in a person who is associated with high STD risk factors.

A pregnancy test must always be performed on all women of childbearing age who are to be tested or screened for STDs. Screening should be done two weeks after a history of exposure to give time for an incubation period in absence of symptoms.

When are tests to diagnose gonorrhea indicated?

Lab tests to diagnose gonorrhea are carried out for the cases:

  • To confirm the presence of gonorrhea in patients with symptoms such as burning urination, penile/ vaginal discharge, itching, etc,
  • Testing may also be done after treating a previously positive case to confirm that the person is cured. However, this is not always done in case the doctor feels the need to do so if the partner has not been screened.
  • To screen pregnant women for gonorrhea
  • To screen the newborn if the mother had gonorrhea at the time of delivery
  • Candidates with STD high-risk lifestyle factors
  • Retesting after three months to rule out the risk of re-infection by your partner

Tests to diagnose gonorrhea

Gonorrhea is diagnosed by testing the urine of the patient and fluids collected from the urethra, vagina, or endocervix, the rectum in case of a history of anal sex, and the oral cavity in case of a history of oral sex.

No medicine should be taken at least 24 hours before the testing and no vaginal cream or douche should be used.

Urine test

Urine is collected for gonorrhea and sent to the lab for a specialized test. The urine sample is collected two hours after the patient has last urinated and the starting stream is collected. These two points are important for the accuracy of results.

Urine collected is sent for Nucleic acid amplification tests (NAAT). NAATs are fairly accurate tests and are based on the amplification of the DNA that is found in Neisseria gonorrhoeae.

These tests include polymerase chain reactions (PCRs) and transcription-mediated amplification (TMA).

These tests are molecular tests and detect and make copies of the DNA of the gonorrhea bacteria. They can also be done on the sample of fluid collected from the vagina or the urethra.

NAATs are considered the gold standard for diagnosing gonorrhea. The U.S. Preventive Services Task Force (USPSTF) found that NAATs testing for gonorrhea had a sensitivity of 90 to 100 percent and a specificity greater than 97 percent.

Testing of body fluids

Although urine testing is good enough in most cases, swab testing of fluids has a slight edge as far as accuracy is concerned.

Fluid material or the discharge is collected with the help of a small cotton swab from the cervical opening, the urethra, the anal canal or the oral cavity as need of sexual history may be. This material is then tested by the following tests.

  • Nucleic acid amplification tests (NAAT).  (explained above). Except that here the fluid from infected areas or suspected areas is sent for testing.
  • Nucleic acid hybridization test (DNA probe test, molecular probe test).  This is molecular probe testing which detects the DNA of the Neisseria gonorrhoeae. This test can differentiate the gonococci from the chlamydia bacteria and is faster than the culture test.
  • Gonorrhea culture. A culture is done of the fluid material collected. Proper testing techniques are necessary for accuracy. If you have taken treatment and the symptoms still persist, this test is advised. This test can also tell to which antibiotics the gonorrhea bacteria are resistant. Treatment can then be changed to an antibiotic to which the bacteria are sensitive. This is the most common test used for diagnosing gonorrhea. It can take from five to seven days to receive the results of a bacterial culture. If there is growth, the test is positive. If there is no growth, the test is negative.
  • Gram stain. A slide is prepared of the material that is obtained from the infected person’s urethra or cervix and stained with a dye that identifies the gonorrhea bacteria. This test is less reliable than the couture or the molecular probe test.
  • Enzyme-linked immunosorbent assay (ELISA, EIA). This test is performed on the fluid or material obtained from the patient. It detects the antibodies that are produced by the immune system to fight the gonococcal infection. This test is not as accurate as the culture test or the molecular probe test.

Blood tests for gonorrhea

The gonorrhea bacteria very rarely pass into the bloodstream. Blood tests look for antibodies, IgG and IgM formed in the blood to the Neisseria gonorrhoeae infection

The blood test cannot tell for certain that an individual has current gonorrhea, but it can tell whether or not the individual has had it in the past. This type of test should not be used to diagnose gonorrhea.

About false positive and false negative test results

Most tests to diagnose gonorrhea can detect infection after one week of exposure. If the test is negative shortly after a high-risk exposure, your doctor may recommend retesting after 2 weeks.

Testing after two weeks can also correctly detect chlamydia, which is the most common STD and often co-exists with gonorrhea.

The specificity of the NAAT, or the rate at which it correctly gives a negative test result is greater than 99 percent. That means, it is not perfect and will have that small potential to give false positive results. The correct and detailed sexual history of the patient, therefore, carries great significance.

The most common reason to get false negative results with gonorrhea tests would be from testing too early after you had sex.

For the urine test, you should not urinate for 2 hours before doing the test. If you give a urine sample before this time interval, it can affect the accuracy of the test.

Therefore, you can be misdiagnosed for gonorrhea for the reasons given above. If you yourself feel that due to your history, you may be infected, you should ask your doctor to retest you at the right time.

However, once diagnosed with gonorrhea, make sure that you take the full course of its treatment for a complete cure and follow prevention tips to avoid getting it again.