Sonographic appearance of the placenta.

The placenta forms the interface between the mother and the fetus and is essential to fetal growth and development. In addition to the exchange of gases and nutrients, it serves immunologic and endocrine functions that protect the fetus and support physiological changes in pregnancy. Although often largely ignored during routine obstetric ultrasound and discarded after delivery, careful sonographic evaluation of the placenta can identify abnormalities that have profound implications for pregnancy outcomes and management. After describing the normal sonographic appearance of the placenta and normal anatomical variations, we review pathologic placental conditions, emphasize ultrasound findings, and highlight implications for pregnancy management and outcomes.