Sonoembryological evaluations of the development of placenta previa and velamentous cord insertion.

Longitudinal and cross-sectional investigations using ultrasound examinations during pregnancy can be used to clarify the mechanisms and pathophysiology of abnormal fetal and placental development. Such sonoembryological assessments are useful as a method for clarifying the etiology of disease. In the present review, we describe current knowledge based on our experience with applying sonoembryological methods to determine the developmental mechanisms of placenta previa and velamentous cord insertion.