Funneling to the stitch: an informative ultrasonographic finding after cervical cerclage

The purpose of this study was to evaluate the utility of ultrasound surveillance after cerclage placement and to propose a rationale for cervical sonography in this setting.

This was a retrospective analysis of 53 women undergoing cervical cerclage by a maternal-fetal medicine specialist, regardless of indication, and delivering between January 1999 and April 2001. Transvaginal ultrasonographic assessment of cervical length and the degree of cervical funneling after cerclage were compared to preoperative values and to outcomes including gestational age at delivery. Funneling to the cerclage was defined as membranes prolapsing down the endocervical canal until they reached the plane of the cerclage.

Cervical cerclage resulted in a significant increase in cervical length from 2.1 +/- 1.2 cm to 2.9 +/- 0.8 cm after the procedure, P < 0.001; however, this measure was not correlated with gestational age at delivery. Funneling to the level of the cerclage 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. A statistically significant association between funneling to the cerclage and preterm delivery was identified irrespective of the indication (prophylactic or emergency) for the procedure. When descent of the membranes to the level of the cerclage was noted, it occurred by 28 weeks' gestation in all patients studied. The incidence of premature rupture of the membranes was also significantly greater postcerclage in women with descent of the membranes to the cerclage (52%) compared to those without this finding (9%) P= 0.002.

Funneling to the cerclage is significantly associated with earlier preterm delivery in patients who have undergone cervical cerclage. Serial sonography up to 28 weeks' gestation is useful in identifying patients at higher risk for premature rupture of the membranes and preterm delivery.