Twenty-four women with second-trimester cervical incompetence underwent emergency cerclage. The appropriateness of cervical cerclage was analyzed according to a scoring system (Cervical Incompetence Scale; CIS) which measures the degree of cervical effacement, cervical dilatation and protrusion of fetal membranes into the cervical canal. Patients with low CIS (0–3 points) were found to have a more favorable pregnancy outcome than patients with high-score cervical incompetence (5–8 points), i.e. fewer complications following the procedure, 33.3 and 87.5%, respectively, fewer pregnancy losses (22.2 and 75%, respectively) and a significantly prolonged postoperative pregnancy course (mean gestation 33.2 and 24.4 weeks at delivery, respectively). The chances of a successful pregnancy outcome were evaluated at 87.5%; the outcome was successful in patients with low CIS presenting with effacement of the uterine cervix of < 50%, cervical dilatation of < 1.5 cm and with fetal membranes remaining in the cervical canal. On the basis of these results, we conclude that the emergency cerclage operation in carefully selected patients with midtrimester cervical incompetence may improve the outcome of pregnancy. This selection is facilitated by the use of a new cervical incompetence scoring system described herein.