Interest of vaginal examination to predict preterm delivery in women with threatened preterm labor

Objective: The aim of this study was to determine whether the vaginal examination is useful to predict preterm delivery when combined with the ultrasound measurement of the cervical length. Design: We conducted a prospective cohort study between January 2013 and January 2015 in Strasbourg University Hospital. We included all the women between 23 and 34 weeks of gestation on a singleton pregnancy with threatened preterm labor. The definition of threatened preterm labor was an ultrasonographic cervical length below 25 mm and presence of regular uterine contractions at a frequency of more than two in 10 min confirmed by external uterine tocometer. Cases of iatrogenic preterm delivery were excluded. We built a multivariable logistic regression model to estimate the significant predictive parameters of spontaneous preterm. The primary outpoint of our study was a preterm birth before 34 weeks of gestation. Results: 395 patients were included in our study. The rate of preterm delivery before 34 weeks was In univariate analysis all the cervical parameters assessed by the vaginal examination were significantly associated with the occurrence of a preterm delivery, like the Bishop score (OR: 1.52 95%IC [1.32–1.77]). All the ultrasound parameters assessed by echography were significantly associated with the occurrence of a preterm delivery like the cervical length (OR: 0.81 95%IC [0.77–0.86]) and the presence of funneling (OR: 4.97; 95%IC [2.6–9.4]). The final model included five variables predicting preterm birth: visualization of the membranes at the speculum exam (OR, 15.8; 95%CI, 2.43–146), ultrasound cervical length (OR, 0.82; 95%CI, 0.75–0.89), biologic inflammatory syndrome (OR, 6.23; 95%CI, 2.07–22.9), gestational age at the hospitalization (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 vaginal examination provided additional predictive value of preterm delivery. Conclusion: Our study suggests that vaginal examination is useless to predict preterm birth in case of threatened preterm labor when performed in combination with speculum examination and endovaginal ultrasonographic scan.