416: The effect of cervical manipulation on fetal fibronectin result: a systematic review

Abstract

The manufacturers of fetal fibronectin (fFN) currently discourage its use after cervical manipulation due to potential iatrogenic expression of the protein. The purpose of this study was to determine if cervical manipulation via sterile vaginal examination (SVE), transvaginal ultrasound (TVU), and/or sexual intercourse affects the accuracy of fFN results. Electronic databases were searched from inception until June 2019. We included all prospective cohort studies that provided fFN results after SVE, TVU, and/or coitus. The primary outcome was agreement between pre-manipulation and post-manipulation swabs, estimated using kappa statistics and proportion agreement with 95% confidence intervals (CI). Secondary outcomes included frequency in which the fFN result changed after cervical manipulation and mean percentage of discordant pairs. Baseline fFN swabs were not obtained in studies examining sexual intercourse; therefore, the results of these articles were examined separately. Outcome data was combined to estimate relative risk of a positive qualitative fFN result after coitus and differences in concentration of quantitative fFN. Of 807 studies identified, 6 were included. Four studies, including 484 pairs of fFN swabs, assessed SVE or TVU. Two studies assessed the effect of coitus on fFN results (121 patients reporting intercourse within 24 hours vs. 141 controls). For SVE and TVU, there was an overall 92.2% (CI 89.3-94.3%) agreement between pre- and post-manipulation swabs with a kappa of 0.703. After SVE or TVU, the fFN result changed from negative to positive and positive to negative 5.3% and 16.5% of the time, respectively. The mean percentage of discordant pairs was 6.9%. Patients who had coitus within 24 hours were more likely to have a positive fFN result (39.7% compared with 7.1%, RR 5.6; 95% CI, 3.0-10.6). Cervical manipulation via SVE or TVU does not significantly affect fFN results; therefore, its use after these exposures is clinically acceptable. Conversely, the use of fFN within 24 hours of sexual intercourse should continue to be discouraged.View Large Image Figure ViewerDownload Hi-res image Download (PPT)