Twin reversed arterial perfusion sequence in twin-to-twin transfusion syndrome after the death of the donor co-twin in the second trimester.

A twin-to-twin transfusion syndrome was diagnosed in a monochorionic-diamniotic pregnancy at 18 weeks' gestation without any malformation, especially heart defect. In spite of the aggressive treatment (serial amnioreduction, digoxin treatment) the donor twin died at 25 weeks and twin reversed arterial perfusion (TRAP) sequence developed and was documented by Doppler ultrasound. In the TRAP-twin, the route of the reversed blood flow from the umbilical arteries was as follows: descending aorta, aortic arch, ascending aorta, aortic valve, left ventricle, mitral valve, left atrium, foramen ovale, right atrium, inferior vena cava, ductus venosus; and back to the placenta through the umbilical vein. After a 12-h observation period the twin reversed arterial perfusion sequence disappeared. During this period ultrasound and fetal blood sampling revealed no sign of fetal anemia or disseminated intravascular coagulation in the surviving twin. Based on our observations, we propose, that the death of one of the twins in monochorionic pregnancy can result in twin reversed arterial perfusion sequence, which is an ultimately rare phenomenon in the second trimester. To our knowledge, this is the first reported case of twin reversed arterial perfusion sequence subsequent to the intrauterine demise of one twin in twin-to-twin transfusion syndrome in which the TRAP-twin had no cardiac malformation.