Management of severe twin to twin transfusion syndrome

Abstract

In monozygotic twin pregnancies embryonic splitting within three days of fertilisation, which occurs in approximately one-third of cases, results in two separate fetuses with independent placental circulations. Splitting after the third day of fertilisation is associated with vascular communications between the placentae; when cleavage is delayed beyond day 12 the fetuses are conjoint. In some monochorionic twin pregnancies imbalance in the net flow of blood across the placental vascular communications from one fetus (the donor) to the other (the recipient) results in twin to twin transfusion syndrome (TTS).