RESUMEN
Cervicovaginal fistula is a recognized complication of induced mid-trimester termination of pregnancy, but more recently it has also been recognized as representing a complication of prior cervical cerclage. We report the ultrasound findings of prolapse of the amniotic sac through a cervicovaginal fistula in a woman with prior cervical cerclage. A woman with cervical incompetence and prior failed McDonald cerclage presented for prophylactic Shirodkar cerclage. Before the procedure, transvaginal ultrasonography revealed a live intrauterine pregnancy at 14 weeks' gestation. Upon further ultrasound examination, the amniotic sac appeared to protrude through the posterior wall of the cervix into the vaginal vault. Pelvic examination verified prolapse of the amniotic sac through a cervicovaginal fistula. The patient underwent an uncomplicated dilatation and evacuation. Women with a history of cervical cerclage are at risk for the development of cervicovaginal fistula, the detection of which is important to prevent potential morbidity.