The accuracy and patient preference for self-collected group B Streptococcus cultures

Abstract

OBJECTIVE: Our purpose was to determine the accuracy of and patient attitudes regarding self-collected group B Streptococcus cultures.

STUDY DESIGN: Women seen for prenatal care at 24 to 42 weeks' gestation were asked to collect distal vaginal and anal samples for group B Streptococcus. Subsequently, distal vaginal and anal samples were obtained by the nurse. The patients were then asked their preference toward self-sampling.

RESULTS: A total of 251 women participated in the study. The incidence of positive group B Streptococcus cultures was 12.7%, 9.6%, 10.0%, and 7.6% for the patient-collected vaginal and anal and nurse-collected vaginal and anal specimens, respectively. The incidence of group B Streptococcus carriage was 17.5% and 13.5% for any positive patient- or provider-collected specimens, respectively, and 19.1% for any positive culture. Single patient-collected vaginal and anal and nurse-collected vaginal and anal samples were insensitive for group B Streptococcus carriage (67%, 50%, 52%, 40%, respectively). The combination of patient-collected samples was more sensitive than nurse-collected samples (sensitivity 91.7% vs 70.8%, p < 0.05). Repeat sampling of the vagina or anal canal did not offer significant additional benefit to a single culture. Overall, patient-collected samples were 98.4% accurate in predicting group B Streptococcus carriage versus 94.4% for nurses. A total of 58% of women preferred obtaining their own specimens, whereas 9.6% found the technique difficult. Ninety percent desired the option of self-sampling in the future.

CONCLUSIONS: Single vaginal or anal cultures were insensitive in detecting group B Streptococcus carriage. Combined patient-collected cultures were more sensitive than provider-collected specimens. On the basis of accuracy and patient preference, women should be given the opportunity of combined vaginal-anal self-sampling for group B Streptococcus when indicated.