Ultrasound of the placenta and umbilical cord: a review.

The placenta and umbilical cord play important roles in the development of the growing fetus. The placenta can be clearly identified by the 14th gestational week and should be evaluated during each obstetric ultrasound examination.This article reviews the formation of the placenta and its expected sonographic appearance throughout gestation along with its normal variants. Expected findings in a singleton pregnancy are primarily addressed. The next portion of the article covers placental abnormalities of clinical consequence, including anomalies of appearance, location, and function.The umbilical cord is also discussed, focusing on the relevance of the location of the umbilical cord's insertion into the placenta.