[Ultrasonic assessment of the state of the cervical canal at the term of pregnancy].
BACKGROUND: To assess if ultrasonic measurement of the cervical canal has carries, at term of pregnancy, a relationship with the onset of labour. To assess if cervical length identifies women at risk to deliver beyond 42 completed weeks of gestation (287 days). METHODS: Prospective case-control study, carried out between 37 and 40 weeks of gestation in uncomplicated, singleton, cephalic presentation, pregnant women. SETTING: outpatient ultrasound Department of a tertiary referral centre, serving > 1000 pregnancies. Weekly measurements of the cervical canal by transvaginal ultrasound probe. RESULTS: Inverse relationship between sonographic measurements and advancing gestational age. At 38 weeks of gestation, significant difference in the ultrasonic recordings between patients delivered before and beyond 41 completed weeks. CONCLUSIONS: It is possible to identify as early as 38 weeks of gestation those women that will deliver beyond 41 weeks. There is a subgroup of nulliparous patients that will probably be candidates to induction of labour.