Rare Pathologic Placenta Ultrasound Findings.

Rare ultrasound placenta findings, such as avascular cystic lesions, hyperechogenic and thick placenta, and enlarged placenta, are associated with infarcts, perivillous fibrin deposition, and mesenchymal dysplasia. These lesions can be present in 20% of normal pregnancies but are more frequent in pregnant women with pre-eclampsia (PE) and/or fetal growth restriction, autoimmune diseases, and infections, and can increase the risk of perinatal complications, including fetal death. Evaluation of the placental surface may also identify cases with circumvallate placenta and chorioangiomas. These rare placental findings require close clinical follow-up and serial fetal evaluations to identify those at a higher risk of abnormal perinatal outcomes.