How is Group B Streptococcus (GBS) screening conducted in pregnancy?

Group B Streptococcus (GBS) screening during pregnancy is primarily conducted via a vaginal-rectal swab. This method is chosen because GBS typically colonizes the lower genital and rectal areas of pregnant women. By collecting a swab from both the vagina and rectum, healthcare providers can accurately determine if GBS is present.

This screening is typically performed between 35 and 37 weeks of gestation, as colonization status can change over the course of the pregnancy. Identifying GBS carriers is crucial since they can transmit the bacteria to their newborns during delivery, leading to serious infections such as sepsis or meningitis in the infant.

Other methods such as blood tests or urine samples are not standard for GBS screening since they do not effectively identify the presence of GBS in the vaginal and rectal areas where it is commonly found. Ultrasound does not serve any purpose in screening for GBS and is used for different aspects of prenatal care, such as assessing fetal development and position.