Group B Streptococcus (GBS) is a common bacterium that can reside in the human body, often without causing symptoms or illness in adults. A specific screening test, known as the GBS swab, is routinely performed during pregnancy to identify pregnant individuals who carry the bacterium, allowing for preventative measures to protect the newborn.
Understanding Group B Streptococcus and Its Importance in Pregnancy
Group B Streptococcus is a type of bacteria that commonly lives in the intestines and the lower genital tract. Approximately 25% of pregnant women may carry GBS, often unaware of its presence. While generally harmless to adults, GBS can pose a risk to newborns during vaginal birth.
The primary concern with GBS in pregnancy is the possibility of transmission to the baby as it passes through the birth canal. If transmitted, GBS can lead to serious health complications for the newborn, including sepsis (blood infection), pneumonia (lung infection), and meningitis (infection of the fluid and lining around the brain). These conditions can be life-threatening for infants. Screening for GBS in late pregnancy helps identify carriers, allowing healthcare providers to reduce the risk of complications for the baby.
Performing the GBS Swab: Timing and Procedure
The GBS swab test is typically performed late in pregnancy, usually between 35 and 37 weeks of gestation. This timing is chosen because it is close enough to the expected delivery date to accurately reflect the GBS status during labor, while allowing sufficient time for test results to be available. The procedure itself is generally quick, simple, and not painful.
During the test, a healthcare provider uses a cotton-tipped swab to collect samples from two specific areas: the lower vagina and the rectum. These samples are then sent to a laboratory for analysis to determine the presence of GBS.
Interpreting GBS Test Results and Subsequent Care
Results are typically available within one to three days. A “positive” GBS test result means the bacteria were detected in the samples, indicating the pregnant individual is a carrier of GBS. It does not mean the individual has an active infection or that their baby will definitely become sick. Conversely, a “negative” result indicates that GBS was not detected in the tested areas, meaning the individual is not likely to be carrying the bacteria at that time.
For individuals who test positive for GBS, the standard medical intervention involves administering intravenous (IV) antibiotics during labor. Penicillin or ampicillin are commonly used antibiotics, given through a vein. These antibiotics are most effective when given at least four hours before delivery, significantly reducing the risk of GBS transmission to the newborn. Antibiotics may also be recommended without a positive test in specific situations, such as premature labor or prolonged rupture of membranes. This preventative strategy has been shown to be highly effective in protecting newborns from GBS infection.