Placental abruption is a serious pregnancy complication where the placenta separates from the uterine wall before the baby is born. The placenta is the baby's lifeline providing oxygen and nutrients. When it separates, the baby loses part or all of its blood supply, and the mother can experience severe bleeding. Abruption can be partial or complete (life-threatening emergency). Bleeding can be revealed (dark red vaginal bleeding) or concealed (blood trapped behind the placenta — no visible bleeding but the uterus becomes rigid and painful). Concealed abruption is more dangerous because severity is underestimated. The classic presentation is painful vaginal bleeding with a rigid, tender uterus in the third trimester. Risk factors include hypertension (the #1 risk factor), prior abruption, abdominal trauma, cocaine use, smoking, and premature rupture of membranes.