Fetal death of one twin in a monochorionic pregnancy with twin-twin transfusion syndrome.

Background: Twin-twin transfusion syndrome (TTTS) occurs in 5-30% of all monochorionic pregnancies. The mortality and morbidity rates are high and therapeutic options limited.

Methods: TTTS in a monochorionic twin pregnancy was initially diagnosed by differences in amniotic fluid volume at 26 weeks. No signs of atrioventricular valve insufficiency or nonimmune hydrops fetalis were present in the recipient. Despite this, the recipient died in utero, whereupon the condition of the donor improved markedly. After spontaneous delivery at 30 weeks' gestation, coarctation of the umbilical cord at its insertion was observed in the recipient, probably secondary to severe torsion.

Conclusions: Unexpected obstetric events may occur in already-complicated pregnancies that are not related to a specific condition, its diagnosis or its therapy.