The importance of funneling to the level of a cervical cerclage

Abstract

Purpose: Our purpose was to evaluate the utility of ultrasound surveillance after cerclage placement and to propose a rationale for cervical sonography in this setting. Methods: A retrospective case series was evaluated. Women undergoing cervical cerclage by a maternal–fetal medicine specialist regardless of indication and delivering between January 1999 and April 2001 were included. Transvaginal assessment of cervical length and the degree of cervical funneling after cerclage were compared to preoperative values and to outcomes. Funneling to the cerclage was defined as membranes prolapsing down the endocervical canal until they reached the plane of the cerclage. Results: A total of 53 cases were available for analysis. Cervical cerclage resulted in a significant increase in cervical length as the mean length increased from 2.1 ± 1.2 cm to 2.9 ± 0.8 cm after the procedure, P < 0.001, but this measure was not correlated with gestational age at delivery. Funneling to the level of the cerclage, however, was associated with an earlier gestational age at delivery 31.3 ± 5.6 weeks vs. 36.8 ± 2.8 weeks for those cases without this finding, P < 0.001. This observation was statistically significant irrespective of the indication for the procedure and was noted by 28 weeks' gestation in all patients followed. The incidence of premature rupture of the membranes was also significantly greater postcerclage in women with descent of the membranes to the cerclage (52%) vs. those without this finding (3%, P = 0.002). Conclusions: Funneling to the cerclage has predictive value for earlier preterm delivery in patients who have undergone cervical cerclage. Serial sonography up to 28 weeks' gestation may be useful in identifying patients at higher risk for premature rupture of the membranes.