A case of a surviving co-twin diagnosed with porencephaly and renal hypoplasia after a single intrauterine fetal death at 21 weeks of gestation in a monochorionic monoamniotic twin pregnancy.

Monochorionic monoamniotic (MM) twin pregnancy carries a high risk of intrauterine fetal death (IUFD). Single IUFD in an MM twin pregnancy prior to 22 weeks of gestation has been reported to be strongly correlated with double twin demise. To our knowledge, there are no case reports on the natural course of a surviving co-twin in an MM twin pregnancy resulting in live birth after a single IUFD prior to 22 weeks of gestation. Here, we report a case of a surviving co-twin, after a single IUFD at 21 weeks of gestation in a MM twin pregnancy, with an antenatal diagnosis of renal hypoplasia and severe neurological damage leading to porencephaly, and live birth at 36 weeks of gestation.