placental abruption, premature separation of the placenta from its normal implantation site in the uterus. The placenta is the temporary organ that develops during pregnancy to nourish the fetus and carry away its wastes.
Placental abruption occurs in the latter half of pregnancy and may be partial or complete. The primary symptom is vaginal bleeding, so extensive in cases of complete separation that replacement of the lost blood by transfusion is necessary. Other symptoms include abdominal pain or back pain, which may be sudden, severe, and constant; uterine contractions, which become frequent and painful; and fetal distress, characterized by reduced fetal movement and reduced fetal heart rate. In instances of complete placental abruption, the infant dies unless delivered immediately. In partial separation the mother is given oxygen, and the infant is delivered as soon as it is safe to do so.
The cause of placental abruption is not known. However, certain factors can significantly increase risk, including advanced maternal age, trauma to the abdomen, preeclampsia (high blood pressure during pregnancy), previous placental abruption in a prior pregnancy, smoking or drug use, multiple pregnancies (twins or triplets).