Ultrasonic imaging of the amniotic and chorionic cavities.

Abstract

This paper presents two cases illustrating separate chorionic and amniotic sacs at 5 to 6 weeks of estimated gestational age. With higher resolution scanning units and higher-frequency transducers, the delineation of the amniotic membrane can be seen before it fuses with the chorionic membrane; this should not be interpretated as an abnormality.