Second-trimester cervical ultrasound: Associations with increased risk forrecurrent early spontaneous delivery

Objective: To determine whether short cervical length or internal os funnel ing before 20 weeks' gestation predicts early preterm birth or pregnancy lo ss in women with at least one prior spontaneous early preterm birth. Methods: Transvaginal cervical ultrasound examinations were done every 2 we eks on 69 women with singleton gestations and histories of at least one pri or spontaneous birth between 16 and 30 weeks' gestation. The results of tho se examinations were correlated with gestational age at delivery. Results: Among 53 women who had ultrasound examinations before 20 weeks' ge station, those with cervical lengths at or below the tenth percentile for t he study population (22 mm, n = 4) or funneling of the internal os (n = 5) were more likely than women without those factors to have spontaneous prete rm births within 2 weeks (33% versus 0%, P = .01) or 4 weeks from the ultra sound examination (67% versus 0%, P < .001) or before 35 weeks' gestation ( 100% versus 19%, P < .001). Short cervical length or funneling between 20-2 4 and 25-29 weeks was also associated with increased risk of spontaneous pr eterm birth before 35 weeks' gestation (P less than or equal to .05 and P = .002, respectively) but not with increased risk of spontaneous preterm bir th within 2 or 4 weeks of ultrasound examination. Conclusion: Women with prior early spontaneous preterm births who have shor t cervical lengths or funneling of the internal cervical os before 20 weeks ' gestation are at increased risk of subsequent spontaneous preterm birth. (C) 2000 by The American College of Obstetricians and Gynecologists.