[A survey of placental separation by real-time B-mode scanning]

Using real-time B-mode Scanning, uteri were observed in 200 cases of delivery focusing on the mechanism of separation and expulsation of the placenta. The following are the main results reported: Ultrasonographically, modes of placental separation and expulsion could be classified into three types, I, II and III. In Type I, soon after the delivery of the fetus, the placenta separated from its bed very smoothly and slid out usually with the first or the second after pains. Blood loss in this type was usually the least, and the duration of the third stage of delivery was the shortest. In Type II, separation of the placenta from its bed began at the marginal site, progressed with each recurring contraction of the uterus. Bleeding was continuous, blood loss tended to be great and expulsation of the placenta was apt to be delayed. In Type III, separation of the placenta started not in the margin but in the central part, and separation progressed as retroplacental hematoma was formed resulting in an increase in the size of the placenta. Blood loss and duration of the third stage of delivery were generally moderate. Among these three types, Type I was the most common, 53 per cent of the cases, and was considered to be the most desirable from the obstetrician's point of view because of the smaller blood loss and the shortening of the third stage of delivery.