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MS WordPerinatologist Corner - C.E.U/C.M.E. Modules
Group B Streptococcal Disease in the Perinatal Period
Sponsored by The Indian Health Service Clinical Support Center
3. Recent history of GBS Prevention and risk factors
Case 3
Alice Koonuk is a 23 y/o G1P1 who has just delivered a 38-week baby girl. Her prenatal care was somewhat spotty and she did not undergo GBS screening at 35-37 weeks. She presented with ruptured membranes of unclear duration, not in labor. Labor was therefore induced and lasted 22 hours. She remained afebrile and did not receive antibiotics. Both she and the baby are doing well. Is antibiotic therapy appropriate for the baby at this time? If so, which drug(s) would you use?
Recent history of GBS Prevention
Both the incidence of disease and the case fatality rate from GBS disease have been steadily decreasing since the widespread implementation of preventive strategies following the 1996 recommendations from the Center for Disease Control (CDC) Prevention of perinatal group B streptococcal disease: a public health perspective, 1996.
Prior to that time two protocols had been in use: the risk-based strategy endorsed by the American College of Obstetricians and Gynecologists (ACOG), and the screening-based strategy endorsed by the American Academy of Pediatrics (AAP).
Both strategies were then merged into one set of guidelines endorsed by all three groups in 1996. In June 1996 ACOG issued ACOG Committee Opinion #173 Prevention of Early-Onset Group B Streptococcal Disease in Newborns.
Risk factors
The principal obstetric risk factors for GBS neonatal infections include:
- fever in labor (>100.4 degrees F)
- prolonged rupture of membranes (>18 hours)
- preterm labor (<37 weeks)
Other significant risk factors include:
- History of a previous infant that was affected with invasive GBS disease
- GBS bacteriuria during the current pregnancy
The screening-based strategy calls for performing vaginal-rectal cultures on all pregnant women at 35-37 weeks gestation. Cost analyses have shown these two strategies are equally cost-effective.
In the July 2002 Schrag et al reported on a large population-based multi-state study has demonstrated that the screening-based strategy is able to prevent more cases of EONS than the risk-based strategy (RR=0.46).
Schrag et al demonstrated that the benefit of screening stems from two main factors:
- screening reaches more of the population at risk who do not necessarily have obstetric risk factors, and
- women who are identified as being GBS positive prior to labor are logistically more likely to receive intrapartum antibiotics.
More history
In August 2002 the CDC endorsed a universal screening-based strategy as superior for the prevention of EONS than the risk-based strategy and issued the CDC Prevention of Perinatal Group B Streptococcal Disease Revised Guidelines (2002). The details, recommendations from these new guidelines are reviewed below. The CDC Recommendations also contain several tables, figures and algorithms.
In December 2002 ACOG issued Prevention of early-onset group B streptococcal disease in newborns. ACOG Committee Opinion No. 279 which adopted the Revised 2002 CDC guidelines.
