The Role of Ultrasound in Third-Trimester Bleeding

Abstract

Bleeding in the third trimester of pregnancy occurs in approximately 4% of all pregnancies. Among these approximately 20% can be attributed to placenta previa and 30% to abruptio placentae. There is increased fetal and maternal morbidity and mortality because of the hemorrhage and placental changes which occur. Known etiologies include multiparity, advanced maternal age, and defective vascularization of the decidua for placenta previa; and a short umbilical cord, polyhydramnios, and prolonged preterm premature rupture of membranes for abruptio placentae. Diagnosis of placenta previa and abruptio placentae by sonography provides essential information for the clinician.