When does death occur in an acardiac twin? Ultrasound diagnostic difficulties

Fetal acardia is a rare abnormality of multiple pregnancies, which is lethal for the affected fetus and can cause death in 50% of normal co-twins. Antenatal recognition with early ultrasound is essential to institute a prospective management to improve the outcome. Our communication outline the difficulties which may be encountered in ultrasound diagnosis. In particular the problem of distinguishing a fetal heart from large pulsating mediastinal vessels, which can be present in these fetuses, and the difficulty of diagnosing death in an acardiac fetus. Our report confirms that the co-twin remains at increased risk of sudden death, even without ultrasound evidence of cardiac failure or biochemical compromise. The finding in this fetus of intravascular fibrin deposits suggests the possibility of acute disseminated intravascular coagulation, not previously reported in association with an acardiac twin.