Objective: To establish a cervical ripening score by transperineal ultrasonography for induction of labor by Prostaglandin E2, and evaluate its predictive effect.
Methods: 105 primiparae underwent cervical assessment by digital and transperineal ultrasonography examination. The five indices of cervical status, other clinical parameters and latency period (from induction to the onset of labor) were analysed by Cox multivariate model.
Results: Transperineal ultrasonography was simple, visualable satisfactorily, noninvasive and less uncomfortable. The width of cervical internal os, the length of the canal and position of the presenting part were the main factors that influenced the latency period (P < 0.05). Primiparae with score > or = -4.5 were easy to initiate the onset of labor within 12 hours (P < 0.001). The predictive results were in good agreement with clinical outcomes, and had less misdiagnosis (the Kappa value, specificity and the positive predictive value were 0.7409, 0.7917 and 0.9254, respectively), and were better than the Bishop score (the corresponding value were 0.5680, 0.6667 and 0.8806, respectively).
Conclusions: Transperineal ultrasonography is safe and effective. In predicting the effect on induction of labor of prostaglandin E2 in primiparae, the transperineal ultrasonographic cervical ripening score is a valuable method.