Group B Streptococcus (GBS) is a common type of bacteria often found in the digestive and genital tracts of healthy adults. It typically does not cause symptoms or harm in adults. However, for pregnant individuals, testing for GBS is a routine part of prenatal care. This screening helps identify those who carry the bacteria, allowing for preventative measures to protect newborns.
What the Group B Strep Test Involves
The Group B Strep test is a quick and straightforward procedure. It involves a healthcare provider taking a sterile swab sample from the lower vagina and rectum. Some individuals may also be given instructions on how to collect the sample themselves at home. The collected sample is then sent to a laboratory for analysis to detect GBS bacteria.
Many people wonder if the GBS test will be painful. Healthcare providers describe the sensation as mild discomfort or pressure, similar to a routine gynecological exam. The swab is soft, and collection typically takes less than a minute. Some might experience a brief sensation akin to a scratch, but it is not usually described as sharp or severely painful.
The test is usually performed late in pregnancy, between weeks 36 and 37. This timing is chosen because GBS bacteria can come and go naturally, so testing closer to delivery provides a more accurate picture of their presence when labor begins. There are no known risks to the pregnant individual from undergoing the GBS test.
Why the Group B Strep Test is Important
The GBS test is important because it identifies pregnant individuals who could pass the bacteria to their baby during childbirth. While usually harmless to adults, GBS can cause serious and potentially life-threatening infections in newborns, such as sepsis, pneumonia, and meningitis. These infections are known as early-onset GBS disease, typically occurring within the first week of life.
Transmission to the baby usually happens during vaginal delivery when the baby comes into contact with bacteria in the birth canal. If a pregnant individual tests positive for GBS and is not treated, there is a 1 to 2 percent chance their baby will develop an infection. The test helps healthcare providers identify carriers and implement preventative measures to significantly reduce this risk. Screening and appropriate treatment have significantly reduced the incidence of early-onset GBS disease in newborns.
Understanding Your Test Results
After the GBS test, results are typically available within 1 to 3 days. There are two main outcomes: negative or positive. A negative result means GBS bacteria were not detected, indicating a low likelihood of transmitting the bacteria to the baby during delivery. No further action is usually needed regarding GBS.
A positive result means the pregnant individual is a GBS carrier. This does not mean the individual is sick or infected, but that the bacteria are present. If the test is positive, the standard course of action involves receiving intravenous (IV) antibiotics during labor. Penicillin or ampicillin are commonly used, given at least four hours before delivery for optimal effectiveness. This treatment significantly reduces the risk of the baby developing early-onset GBS disease, from about 1 in 200 without treatment to approximately 1 in 4,000 with antibiotics.