Morgan C L, Trought W S
Rev Interam Radiol. 1979 Jan;4(1):19-20.
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.
本文介绍了两例病例，显示在估计孕周5至6周时存在独立的绒毛膜囊和羊膜囊。使用分辨率更高的扫描设备和频率更高的换能器，可以在羊膜与绒毛膜融合之前看到羊膜的轮廓；这不应该被解释为异常。
