In Brief BACKGROUND Fetal head entrapment during delivery is a rare occurrence in modern obstetrics. We present a case of intrauterine head entrapment of a second twin by a uterine synechia diagnosed by ultrasound and subsequent complications that occurred. CASE A woman with a twin intrauterine pregnancy presented at 19 weeks for evaluation of a shortened cervix. Ultrasound examination demonstrated fetal head entrapment of twin B by a uterine synechia, as well as intrauterine growth restriction (IUGR). The patient experienced pre-term premature rupture of membranes at 24 weeks' gestation and underwent a cesarean delivery for a nonreassuring fetal heart rate tracing of twin B, with findings of a constricting band of fibrous tissue around the neck of twin B. CONCLUSION Uterine synechia might cause intrauterine head entrapment and IUGR. Uterine synechia might cause intrauterine head entrapment and intrauterine growth restriction and can be diagnosed by antenatal ultrasound.