[The "vanishing twin"]. / Zur Frage des "Vanishing Twin".

Three cases of a vanishing twin are reported. We observed twin pregnancies in three women, who had their ultrasound examination before the 10th week of pregnancy. Positive heartbeat was registered in both embryos. When a further sonographic examination took place at the 11th week, intrauterine death of one of the embryos was observed. All three pregnancies continued as singleton pregnancies to uneventful term deliveries. When the placentae and chorionic membranes were examined after delivery, small nodular pigmented areas were observed. Histological examination showed the remains of the embryo, who had vanished in the first trimester of pregnancy.