Mulhair L, Carter J, Poston L, Seed P, Briley A. BJOG. 2009 Jan;116(2):313-8.
Abstract: OBJECTIVE: This study investigated the reliability, sensitivity and specificity of a commercially available absorbent pad, AmnioSense, compared with speculum examination for detection of spontaneous ruptured membranes (SRM). DESIGN: Prospective cohort study. SETTING: Antenatal Day Unit (ADU) of a UK inner-city teaching hospital. POPULATION: Women attending the ADU with a history of suspected ruptured membranes between 18 and 42 weeks of gestation. METHODS: Eligible women were asked to use the absorbent pad in accordance with the manufacturer’s instructions. A midwife recorded the result. A second midwife performed a speculum examination according to unit protocol. Results were entered onto a password-protected study-specific database. Both midwives were blind to the other test result. MAIN OUTCOME MEASURES: Comparability between the index test (AmnioSense) and reference standard (speculum). RESULTS: A total of 157 women were recruited and results were analysed in 139 cases. Median gestational age at recruitment was 37(+2) weeks. The prevalence of SRM was 42% (59/139) with AmnioSense giving a sensitivity of 98% (58/59) and specificity of 65% (52/80). CONCLUSIONS: Thirty-eight percent (53/139 women) with SRM would have been correctly identified as having intact membranes without the need for a speculum examination. Twenty-five percent of AmnioSense false-positive results were associated with positive high vaginal swab results (7/28). These data suggest that a negative AmnioSense result can provide reassurance of intact membranes. Use of the AmnioSense test before considering speculum examination could reduce the number of speculum examinations undertaken, with benefit to women and concomitant health resource savings.