Sonographic anatomy of the normal placenta

Abstract

The normal anatomy of the placenta and the retroplacental area can be well defined with gray scale sonography. The placenta has a characteristic granular echo pattern, with strong echoes emanating from the chorionic plate. After 37 weeks, strong echoes representing calcification may appear; this is a normal physiologic process. The significance of early calcification is unclear. The retroplacental myometrium and venous drainage of the placenta are easily visualized by sonography. Variations in the appearance of the retroplacental myometrium result from different degrees of bladder filling and from uterine contractions. These normal retroplacental structures should not be mistaken for myomas or hematomas.