The microbiological effects of endovaginal sonographic assessment of cervical length.

OBJECTIVE: To determine whether performance of endovaginal sonography for the measurement of cervical length results in a statistically significant change in endocervical culture results. METHODS: Women attending a routine prenatal clinic were offered enrollment in the study. Exclusion criteria included the presence of a cervical cerclage, vaginal examination or coitus within the preceding 24 hours, antibiotic therapy within the preceding 7 days, or the presence of ruptured membranes. A sterile speculum examination and collection of cervical cultures were performed before (initial) and immediately after (final) endovaginal sonographic measurement of cervical length. Quantitative cultures were completed and evaluated for differences in growth by a standardized 4-quadrant technique. RESULTS: A total of 25 women enrolled and completed the study protocol. Quantitative assessment of colony growth showed that the mean growth in the initial samples +/- SD was 3.48+/-1.74, with 1+ indicating growth in 1 quadrant; 2+, growth in the first and second quadrants; 3+, growth in the first, second, and third quadrants; and 4+, growth in all quadrants. The mean growth cultured in the final sample was 3.79+/-2.26 (P = .364; 95% confidence interval of the difference, -1.00 to +381). CONCLUSIONS: The results of this study do not show a statistically significant inoculation effect associated with performance of endovaginal sonography for the measurement of cervical length.