📖 Definition
Defined as blood loss of more than 500 mL after vaginal delivery or 1,000 mL after C-section, or any blood loss causing hemodynamic instability. The most common cause is uterine atony (failure of the uterus to contract after delivery). Treated with uterotonic drugs (Pitocin, misoprostol), uterine massage, balloon tamponade, or surgery. Routine Pitocin after delivery significantly reduces risk.