Health Guide

Group B Streptococcus screen, rapid

What is this test?

This test rapidly detects the presence of bacteria called group B streptococcus (GBS). It is used when GBS carrier status (to be infected with this bacteria and not show any symptoms) is suspected in women[1][1][2][3].

What are other names for this test?

  • Streptococcus agalactiae latex screen
  • Streptococcus Group B latex screen

Why do I need this test?

Laboratory tests may be done for many reasons. Tests are performed for routine health screenings or if a disease or toxicity is suspected. Lab tests may be used to determine if a medical condition is improving or worsening. Lab tests may also be used to measure the success or failure of a medication or treatment plan. Lab tests may be ordered for professional or legal reasons. You may need this test if you have:

  • Group B Streptococcus carrier

When and how often should I have this test?

When and how often laboratory tests are done may depend on many factors. The timing of laboratory tests may rely on the results or completion of other tests, procedures, or treatments. Lab tests may be performed immediately in an emergency, or tests may be delayed as a condition is treated or monitored. A test may be suggested or become necessary when certain signs or symptoms appear.

Due to changes in the way your body naturally functions through the course of a day, lab tests may need to be performed at a certain time of day. If you have prepared for a test by changing your food or fluid intake, lab tests may be timed in accordance with those changes. Timing of tests may be based on increased and decreased levels of medications, drugs or other substances in the body.

The age or gender of the person being tested may affect when and how often a lab test is required. Chronic or progressive conditions may need ongoing monitoring through the use of lab tests. Conditions that worsen and improve may also need frequent monitoring. Certain tests may be repeated to obtain a series of results, or tests may need to be repeated to confirm or disprove results. Timing and frequency of lab tests may vary if they are performed for professional or legal reasons.

How should I get ready for the test?

Ask the healthcare worker for information about how to prepare for this test.

How is the test done?

A sample of vaginal cells and discharge, or anal cells may be collected for this test. Both of these samples may be needed for this test.

Vaginal cells/discharge:

A vaginal swab is done to collect a sample from the lower part of your vagina. You will be asked to lie on your back with your legs spread and feet placed on stirrups. A special kind of swab will be inserted into your lower vagina or just near the entrance of the vagina. The swab will be rotated gently and then remain still for a few seconds before it is removed. This is done make sure enough secretions have been collected for the test. The sample is then sent for testing.

Anal cells:

An anal swab is done to collect a sample from your rear end. You may be asked to lie on your back with your legs spread and feet placed in stirrups. A special kind of swab will be inserted an inch into your rear end. The swab will be rotated gently before it is removed. The sample is then sent for testing.

How will the test feel?

The amount of discomfort you feel will depend on many factors, including your sensitivity to pain. Communicate how you are feeling with the person doing the test. Inform the person doing the test if you feel that you cannot continue with the test.

Vaginal cells/discharge:

During a vaginal swab, you may feel discomfort when the swab moves in your vagina.

Anal cells:

During an anal swab, you may feel discomfort when the swab moves in your rear end.

What should I do after the test?

There are no special instructions to follow after this test.

What are the risks?

Vaginal cells/discharge: Ask the healthcare worker to explain any risks of this test to you before it is performed.

Anal cells: Ask the healthcare worker to explain any risks of this test to you before it is performed.

What are normal results for this test?

Laboratory test results may vary depending on your age, gender, health history, the method used for the test, and many other factors. If your results are different from the results suggested below, this may not mean that you have a disease. Contact your healthcare worker if you have any questions. The following is considered to be a normal result for this test:

What follow up should I do after this test?

Ask your healthcare worker how you will be informed of the test results. You may be asked to call for results, schedule an appointment to discuss results, or notified of results by mail. Follow up care varies depending on many factors related to your test. Sometimes there is no follow up after you have been notified of test results. At other times follow up may be suggested or necessary. Some examples of follow up care include changes to medication or treatment plans, referral to a specialist, more or less frequent monitoring, and additional tests or procedures. Talk with your healthcare worker about any concerns or questions you have regarding follow up care or instructions.

Where can I get more information?

Related Companies

  • Centers for Disease Control and Prevention (CDC) -
  • American Academy of Family Physicians -


[1] Schrag S, Gorwitz R, Fultz-Butts K: MMWR: Prevention of perinatal Group B Streptococcal disease. CDC. Atlanta, Georgia. 2002. Available from URL:

[2] Bergeron MG, Ke D, Menard C, et al: Rapid detection of Group B Streptococci in pregnant women at delivery. N Engl J Med 2000; 343:175-179.

[3] Donders GG, Vereecken A, Salembier G, et al: Accuracy of rapid antigen detection test for Group B Streptococci in the indigenous vaginal bacterial flora. Arch Gynecol Obstet 1999; 263:34-36.

Last Updated: 7/4/2018
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