Strategies to decrease costs associated with GBS prophylaxis in preterm gestations

Objective: 1) To evaluate the costs associated with a practice of routinely culturing women for Group B beta-Streptococcus (GBS) who are at risk for preterm delivery. 2) To evaluate the charges associated with a policy of empiric antibiotic therapy in women suspected of imminent delivery prior to 37 weeks gestation.Methods: In our hospital, women who present with preterm contractions (PTC), preterm labor (defined as uterine contractions resulting in cervical change, PTL), and preterm rupture of the membranes (PROM) were cultured for GBS. Women with PTL and PROM received parenteral antibiotic therapy pending availability of culture results (48 hours). We reviewed the records of women who participated in a study to determine the sensitivity and specificity of a rapid test for GBS (Am J Obstet Gynecol 1997;176:S35). Results of the Lim broth culture, our gold standard, were used for this analysis. The charges for performing cultures ($32/culture) and administering intravenous ampicillin ($54/dose) were calculated.Results: There were 118 women with PTC, 52 women with PTL, and 64 with PROM. Thirty-four (14.5%) of the cultures were positive. The results are presented below.In women with PTC, the incidence of GBS was 12.7%. The culture results were available and guided care in only the 6 women who delivered between 2 and 7 days. In women with PTL the incidence of positive cultures was 11.5%. All of the women received antibiotics pending results of cultures. The majority of the women had delivery delayed 48 hours until results were available. Care was modified in the 7 women who delivered between 2 and 7 days. In women with PROM the incidence of GBS was 20.3%. The culture results were available and guided therapy in 11 women.Conclusions: Our findings suggest that GBS cultures have limited clinical value in women with PTC. Only 6 women, 5.5%, had their care modified as a result of the cultures, at a cost of $3776. In women with PTL, we over-treated the majority of women with antibiotics, most of whom delivered after culture results were available. Cultures had minimal impact on management. Antibiotics should be reserved for women whose labor is progressing on tocolysis. In women with PROM, most delivered prior to availability of culture results. We would have saved $2048 had no cultures been obtained. These results are probably irrelevant, if routine antibiotic administration is utilized in PROM to prolong latency intervals regardless of GBS status.