Group B streptococcus (GBS) screen



Group B streptococcus on Blood Agar

  • This investigation is performed on selected patients in late pregnancy to assess for carriage of group B streptococci (Streptococcus agalactiae).
  • Selective testing follows national guidelines. Testing is done to reduce the incidence of early onset group B streptococcal (GBS) infection in neonates.
  • Current methodology is based on culture.
  • See also:

Sample requirements

Standard charcoal transport swab

Lower vaginal swab

Place swab into transport medium

Charcoal transport swab

Required information

  • Gestation
  • Any risk factors for GBS infection


Store and transport at room temperature. Samples should be transported to the laboratory with minimal delay.

Turnaround time

Negative 1 - 2 days

Positive 2 - 3 days

Page last reviewed: 06/08/2014