Group B Streptococcus by PCR, Routine Prenatal Screening

Test Mnemonic


CPT Codes

  • 87653 - QTY (1)




  • agalactiae
  • GBS

Performing Laboratory

Cleveland Clinic Laboratories

Specimen Requirements

Volume Type Container Collect Temperature Transport Temperature Special Instructions
OneVaginal/rectalSwab, culturette  Collect specimen with Cepheid Collection Device, Oracle 1616432.
OneVaginal/rectalE Swab   


Environmental Condition Description
Ambient24 hours
Refrigerated2 days
FrozenUnacceptable. Will be rejected.

Days Performed

7 days a week

Turnaround Time

2 days


Name Description
Polymerase Chain Reaction (PCR) 

Reference Range

Special Info

Specimens must be collected by swabbing the distal vagina, followed by the rectum (insert swab through the anal sphincter using the same swab). After receipt into the lab, the specimen is incubated for 18-24 hours in an appropriate enrichment broth medium prior to testing in order to enhance the detection of GBS. Stability of the swab specimen is 24 hours at room temperature, 6 days at 2-8C. Frozen specimens are unacceptable and will be rejected.

Clinical Info

Many women harbor Group B streptococci (Streptococcus agalactiae) that can cause infections during pregnancy or in neonates after birth. This test is intended for screening of pregnant women for vaginal and rectal Group B streptococcal colonization between 35 and 37 weeks gestation. Testing is performed 7 days/week, 24 hrs/day. If the patient is ß-lactam allergic, susceptibility testing should also be ordered. For the diagnosis of GBS disease, routine culture of the symptomatic body site (e.g., blood, CSF, amniotic fluid, joint fluid) should be ordered rather than a screening test.