Diagnosis of twin reversed arterial perfusion sequence in the first trimester by transvaginal color Doppler ultrasound

A case of twin reversed arterial perfusion (TRAP) sequence was diagnosed at 12 weeks' gestation using transvaginal color Doppler ultrasound, which dem onstrated the presence of retrograde perfusion in the umbilical artery of t he abnormal twin. Ultrasound imaging showed a monochorionic-diamniotic twin pregnancy with an inappropiately grown second twin, the morphological eval uation of which revealed an abnormal cephalic pole with acrania, diffuse su bcutaneous edema and the presence of cardiac activity in an abnormal heart with a single chamber.