A cross-sectional study was conducted to evaluate the efficacy of rescue cerclage in patients with a dilated cervix and prolapsed foetal membranes. Thirty-five patients presenting with cervical dilatation and prolapsed foetal membranes were included in the study. A McDonald cerclage was placed in 27 patients. The duration of pregnancy prolongation and the number of deliveries after 28 weeks were evaluated. The median prolongation of pregnancy after cerclage placement differed significantly between the cerclage and bed-rest groups (64 days versus 13.5 days). Of the 27 patients who had cerclage, 17 (63%) delivered after 28 weeks of gestation, whereas all patients in the bed-rest group delivered before 28 weeks of gestation. The take-home baby rate was 63% in the cerclage group. When pregnancies were complicated by cervical dilatation with membrane prolapse into the vagina, placement of a McDonald cerclage in appropriately selected patients can be a beneficial therapeutic option.