The antenatal diagnosis of placenta accreta

Abstract

The antenatal diagnosis of placenta accreta is invaluable in planning an approach to delivery or to management of an early intrauterine demise. The women most at risk are those who have had uterine surgery and have placenta previa, but placenta accreta can occur in any pregnancy. In early pregnancy the most useful ultrasound finding is implantation of the sac over a uterine scar. Vascular sinuses, appearing as early as 15 weeks, are irregularly shaped, have obvious blood flow when evaluated with color Doppler, and have the highest sensitivity for placenta accreta. Loss of the usual retroplacental clear space as a sole finding will usually be false positive. Magnetic resonance imaging diagnosis is in its infancy and has not yet been proven to add information unless the placenta is posterior. In the future it will hopefully aid in distinguishing placenta accreta from percreta.