A comparison of vaginal ultrasound and digital examination in predicting preterm delivery in women with threatened preterm labor: a cohort study

Introduction. The aim of this study is to evaluate the utility of digital examination in addition to ultrasonic measurement of cervical length for predicting spontaneous preterm delivery in women with threatened preterm labor. Material and methods. This was a prospective cohort study in Strasbourg University Hospital, France, between January 2013 and January 2015. All women with a singleton pregnancy hospitalized with threatened preterm labor between 23 and 34 weeks of gestation were included. Cases of iatrogenic preterm delivery were excluded. A multivariable logistic regression model to estimate the significant predictive parameters of spontaneous preterm delivery was performed. The primary endpoint of our study was a preterm birth before 34 weeks of gestation. Results. A total of 395 women were included in our study. The rate of preterm delivery before 34 weeks was 13%. In univariate analysis every single cervical parameter assessed by the digital examination and all the ultrasound parameters were significantly associated with preterm delivery. The final model included five variables predicting preterm birth: visualization of the membranes at the speculum examination (OR 15.8, 95% CI 2.43-146), ultrasound cervical length (OR 0.82, 95% CI 0.75-0.89), signs of inflammation (OR 6.23, 95% CI 2.07-22.9), gestational age on admission (OR 0.84, 95% CI 0.71-1.0), and presence of vaginal infection (OR 4.28, 95% CI 1.52-12.7). None of the cervical parameters assessed by the digital examination provided additional predictive value of preterm delivery. Conclusion. Our study suggests that digital examination does not add to the information given by vaginal ultrasound evaluation in predicting preterm labor.