What condition is characterized by maternal blood loss exceeding 500ml after vaginal delivery?

Postpartum hemorrhage is defined as the loss of more than 500 milliliters of blood following a vaginal delivery. It is a significant and potentially life-threatening condition that can occur due to various reasons, such as uterine atony, retained placental fragments, or lacerations. Recognizing postpartum hemorrhage is crucial for timely intervention to prevent severe complications for the mother.

In the context of the other options, while conditions like placenta accreta or uterine rupture can lead to complications following delivery, they are not exclusively defined by the specific blood loss threshold identified in the question. Preeclampsia, on the other hand, is primarily a hypertensive disorder of pregnancy and is characterized by high blood pressure and protein in the urine rather than blood loss after delivery. Thus, postpartum hemorrhage is the most accurate term associated with the stated condition of blood loss exceeding 500 milliliters after vaginal delivery.