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-diamni otic pregnancy at 18 weeks' gestation with out 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 arter ial perfusion (TRAP) sequence developed and was documented by Doppler ultra sound. In the TRAP-twin, the route of the reversed blood flow from the umbi lical arteries was as follows: descending aorta, aortic arch, ascending aor ta, 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 rever sed arterial perfusion sequence disappeared. During this period ultrasound and fetal blood sampling revealed no sign of fetal anemia or disseminated i ntravascular coagulation in the surviving twin. Based on our observations, we propose, that the death of one of the twins in monochorionic pregnancy c an result in twin reversed arterial perfusion sequence, which is an ultimat ely 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 syndrom e in which the TRAP-twin had no cardiac malformation.