This is a cross section of a term placenta to reveal a large hematoma that covers most of the maternal surface. Such a retroplacental hematoma is known as abruptio placenta. A small hematoma may not compromise fetal viability, but a larger hematoma can, and is an emergency. Abruption may be accompanied by sudden onset of maternal severe lower abdominal or pelvic pain. This complication of pregnancy typically occurs in the third trimester from premature separation of the placenta.