Omphalocele-Exstrophy-Imperforate Anus-Spinal Defect Syndrome in a monozygotic twin pregnancy: a case report and literature review

Abstract Background The Omphalocele, Exstrophy, Imperforate Anus, and Spinal Defects Complex (OEIS complex) is a rare condition. The prevalence of this condition ranged from 1 in 200,000 to 400,000 pregnancies and 1 in 82,000 to 200,000 live births. There have been cases of female monozygotic twins with this condition, but the perinatal outcome of the co-twin has not received sufficient attention. Case presentation We present a spontaneously conceived monochorionic monoamniotic twin pregnancy with OEIS in one twin. At 12 + 4 weeks’ gestation, ultrasound suggested MCMA twin pregnancy and twin B with abdominal cystic mass 2.8*2.5*2.5cm. At 15 + 3 weeks’ gestation, the abdominal cystic mass in Twin B was detected enlargement as 5.76*3.13*5.4cm. Subsequent prenatal examinations confirmed the presence of OEIS in Twin B. At 20 + 4 weeks, the abdominal cystic mass measured 7.0*4.7*6.2 cm, and the mass suddenly decreased to 3.3 *2.5*2.0 cm at 22 weeks ,which suggested membrane rupture of the cystic mass. At 33 + 6 weeks, the OEIS fetus underwent selective feticide by intrafetal laser therapy after multidisciplinary consultation, and then the caesarean section was performed. The OEIS fetus was weighed 1769g, with no external genitalia and anus, and presented with a bulging of 3 x 4 cm at the umbilical location. The healthy female baby weighing 2020g was delivered, with Apgar scores of 8 and 9 at the first and fifth minute, respectively. The baby was followed up and now at one year and 6 months old is in good health. Conclusion(s) OEIS syndrome appears to be more commonly observed in monozygotic twins. The difference in prevalence of OEIS syndrome between males and females is not significant. In discordant twin pregnancies where only one fetus has OEIS, the co-twin has a higher chance of survival with no malformations, and feticide should be considered in such cases. In concordant twin pregnancies where both fetuses are affected by OEIS, the prognosis is poor.