[Monoamniotic multiple pregnancies].

Monochorionic monoamniotic (MCMA) multiple pregnancies are rare events with an incidence of around 0.004% of all life births. They are the result of a delayed splitting of a single blastocyst whereby the stimuli and mechanisms are still unknown. The Incidence of MCMA multiple pregnancies is increased after artificial reproductive techniques. With the advent of modern ultrasonography the diagnosis of MCMA multiple pregnancies and the combined complications such as cord entanglement, malformations including the incidence if conjoined twins and even threatening preterm delivery or twin-twin transfusion syndrome has improved. The chances of intact survival of up to 80-90% have improved through intensified surveillance. It is recommended to perform a Cesarean section at around 32 gestational weeks. Postnatal investigations of the placenta and its anastomoses have increased our understanding of the pathophysiology of MCMA multiple pregnancies.