The Prevalence of Expired GBS Screens Among Women Delivering at Term [36N]

Abstract

INTRODUCTION: A 2019 committee opinion from the American College of Obstetrics and Gynecology [ACOG] recommended delaying the antenatal GBS screen until 36–37 weeks to reduce the number of women delivering at term with an expired GBS screen. The purpose of this pilot study was to determine, in a large private practice setting, the proportion of women delivering at term (37 weeks or greater) with an expired GBS negative screen. METHODS: We retrospectively examined the charts of all women in a large multispecialty practice in Nevada who delivered between January 1 and June 30, 2018. RESULTS: We initially examined 199 charts. The median gestational age at delivery was 39.1 weeks (IQR 38.4 to 40 weeks). The median age of our study population was 30 (IQR 24 to 33 yrs). There were 149 patients who had a documented GBS result and of these 149 patients, 123 (82.5%) had a negative GBS screen. There were 103 patients who delivered at term, were GBS negative at their initial screen, and for whom both delivery date and GBS screen date were available. Among this subgroup, 9 patients had an interval greater than 35 days (8.74%). These 9 patients had GBS screen-to-delivery intervals of 36 (n=5), 37 (n=1), 39 (n=2), and 49 days (n=1), respectively. CONCLUSION: We found that approximately 1 out of 11 women in our practice delivered at term with an expired GBS screen. If our results are replicated in larger studies, it would provide further evidence to support the recent ACOG recommendations to delay GBS screening to 36–37 weeks.