Fig. 1From: Monozygotic dichorionic-diamniotic pregnancies following single frozen-thawed blastocyst transfer: a retrospective case seriesThe images of the initial ultrasound at gestational 6–7 weeks. Case 1 to 6: gestational 6–7 weeks` ultrasound with 2 gestational sacs and 2 fetal poles. Case 7 to 13: gestational 6–7 weeks` ultrasound with 2 gestational sacs and 1 fetal poleBack to article page