A 29-year-old pregnant woman with parity 0-0-0-0 visited the hospital at 14 weeks after spontaneous pregnancy. Abdominal 2D ultrasound (Voluson E8, GE Healthcare, USA) revealed that the first twin was within the normal ranges for the gestational age but the second twin showed anencephaly. There was one placenta and no amniotic membrane separated the two fetuses, and both were male. Umbilical cord entanglement was observed by using 3D ultrasound (Voluson E8, GE Healthcare, USA) (Fig. 1). The parents received counseling regarding monoamniotic twin pregnancy, anencephaly of a fetus and complications of umbilical cord entanglement. The patient underwent weekly prenatal medical examinations at the outpatient clinic. A fetal ultrasound conducted at 22 weeks did not show any abnormal finding except for one fetal anencephaly (Fig. 2). Starting from 26 weeks, a Doppler study of the umbilical cord and a non-stress test were performed every week and their results were within normal ranges. Also, amniotic fluid index (AFI) was checked every week, polyhydramnios (AFI = 25) was detected at 26 weeks and persisted until delivery (AFI: 20 ~ 28). The polyhydramnios was asymptomatic and was not treated. Although hospitalization for intensive observation was recommended at 30 weeks of pregnancy, the patient refused such treatment. While she was examined as an outpatient, preterm labor occurred at 33+5 weeks and she was subsequently hospitalized.
A single course of steroids for lung maturation were given immediately after hospitalization. The heartbeat of the 2 fetuses were 140 beats/min and 130 beats/min, respectively and showed normal variability, and 20~30 mmHg uterine contractions were observed every 3 minutes. At 34 weeks a Cesarean section was performed under general anesthesia. The first male infant had a weight of 2,210 g, and his Apgar scores at 1 and 5 minutes were 6 and 8, respectively. No gross abnormalities were observed. The second infant weighted 1,380 g and his Apgar scores at 1 and 5 minutes were 1 and 0, respectively. Other than anencephaly, no gross abnormalities were observed in the second twin. The first twin was moved to the neonatal intensive care unit immediately after Cesarean section and was cared for without intratracheal intubation or use of a ventilator. He was discharged without any complications on the fifth day after birth and the mother was also discharged without any unusual findings on the same day.
The gross findings for the umbilical cord were very similar to that of umbilical cord entanglement observed through 3D ultrasound at 14 weeks (Fig. 3).