EP12.14: Discordant monochorionic monoamniotic twin malformation: omphalocele-exstrophy-imperforate anus-spinal (OEIS)defect complex

The OEIS complex is a rare malformation. The prevalence ranges from 1 in 200,000 to 400,000 birth, with higher rates in female. We present a case that demonstrates the imaging features of OEIS complex, with also has the rare diagnosis of a sacral myelocistocele in a twin B of a mochorionic monoamniotic pregnancy. A 28-year-old mother, gravida 1, para 0, presenting with a spontaneous monochorionic monoamniotic pregnancy was referred at 13 weeks because of a suspected omphalocele in twin B. The couple had no personal or family history of congenital anomalies. At successive ultrasound scans at SAMSUNG WS80, the amnionicity and normality of the female twin A was confirmed. Twin B presented several following anomalies: omphalocele, exstrophy of cloaca, and spinal defects. We suspected OEIS complex. Amniotic fluid volume was normal on repeat scans. Magnetic resonance imaging (MRI) of twin B showed omphalocele, infraumbilical mass connected to gut tract, absent bladder and spinal defect. After prenatal counselling, selective termination of pregnancy was considered but not chosen by the parents. A Caesarean section was performed at 32 weeks, indicated because of pre-eclampsia. The female twin A (2,120 g) had no malformation. Twin B (2,035 g) the umbilical cord was low set on the anterior abdominal wall and was associated with an omphalocele. The rectum had a blind end, terminating in the omphalocele. The pelvi-calyceal system and kidneys were normal, a bilateral opening of the ureters at the base of the omphalocele, suggesting bladder exstrophy. Sacral closed spina bifida was confirmed. The umbilical cord above the omphalocele contained three vessels. The perineum was smooth, not showing any urethral or anal opening. On day of life 02, the twin B underwent closure repair of the cloacal exstrophy, with diverting loop ileostomy, pelvic closure, abdominal wall closure and bladder reconstruction. Twin A was discharged at day of life 19 and twin B at day 32 of life.