Change in cervical length after prophylactic cerclage

To determine changes in length of incompetent cervices after cerclage, using transvaginal ultrasound.

Patients were enrolled in a prospective, observational study under an Institutional Review Board-approved protocol. McDonald or Shirodkar sutures were placed according to physician preference. Pre- and postcerclage cervical lengths were measured within 72 hours of the procedure. At each examination, the first measurement was discarded, and a mean of the subsequent three measurements was calculated.

Twenty-one Shirodkar and ten McDonald operations were done. The mean (+/- standard deviation) precerclage cervical length was 2.7+/-0.9 cm and the postcerclage cervical length was 3.6+/-0.9 cm (P<.001, paired t test).

Prophylactic cerclage results in measurable increases in cervical length, which might contribute to the success of the procedure. Further study is needed to determine whether the degree of cervical lengthening after cerclage predicts term delivery.