Using ultrasound in the clinical management of placental implantation abnormalities.

Placental implantation abnormalities, including placenta previa, placenta accreta, vasa previa, and velamentous cord insertion, can have catastrophic consequences for both mother and fetus, especially as pregnancy progresses to term. In these situations, current recommendations for management usually call for an indicated preterm delivery even in asymptomatic patients. However, the recommended gestational age(s) for delivery in asymptomatic patients are empirically determined without consideration of the recent literature regarding the usefulness of specific ultrasound findings to help individualize management. The purpose of this article is to propose literature-supported guidelines to the current opinion-based management of asymptomatic patients with placental implantation abnormalities based on relevant and specific ultrasound findings such as cervical length, distance between the internal cervical os and placenta, and placental edge thickness.