Ultrasound findings of a HCSP. Longitudinal section of the uterus showing the coexistance of an intrauterine pregnancy with a live embryo (F2, crown–rump length:11.1 mm) and a gestational sac with a dead embryo (F1, crown–rump length:3 mm) implanted into the lower segment Cesarean section scar in Case 9 at 7 + 4 weeks