Monochorionic monoamniotic twins--the most precarious of twin pregnancies.

Monochorionic monoamniotic twins have a high perinatal mortality rate. Death usually occurs before 24 weeks' gestation, mainly because of cord entanglement, prematurity, congenital anomalies or twin-to-twin transfusion. These possibilities should be taken into account when twin pregnancies are detected at the ultrasound screening between 17 and 20 weeks' pregnancy. We report here a case where monochorionic monoamniotic twins were born at 34 weeks, with massive cord entanglement and we describe the antenatal care at our clinic.