[The value of intravaginal ultrasonography of the cervix uteri for evaluation of the risk of premature labor].

OBJECTIVE: To determinate the predictive value of cervical length, measured by transvaginal ultrasound, for preterm delivery among patients with signs of preterm labor.

PLACE: Department of Gynecology & Obstetrics, Poissy Hospital Center.

MATERIAL AND METHODS: A prospective study that measured cervical length by transvaginal ultrasound was performed among 108 patients with a singleton pregnancy hospitalized with signs of premature labor between 24 and 34 weeks' gestation or within 21 days of inclusion.

RESULTS: The rate of preterm birth was 22.2% (24/108). When cervical length was < or = 26 mm, the gestational age at delivery was significantly lower that when it exceeded 26 mm (36.3 +/- 3.0 weeks compared with 38.5 +/- 2.1 weeks; p < 0.0001). 40.4% (19/47) of patients whose cervical length was < or = 26 mm gave birth prematurely, compared with only 8.2% (5/61) of those with a cervix > 26 mm The sensitivity, specificity, positive predictive value, and negative predictive value of transvaginal ultrasonography were, respectively, 79.2, 66.6, 40.4, and 91.8% for delivery before 37 weeks' gestation, and 75.0, 62.0, 25.5, and 93.4% for delivery within 21 days of the ultra-sound measurement.

CONCLUSION: Transvaginal ultrasound of the cervix provides an objective method for evaluating the risk of preterm delivery. Its predictive values are impressive and allow better discrimination between women at high risk of preterm delivery and those in false preterm labor.