Final answer:
Placental abruption is a serious complication of pregnancy that involves the separation of the placenta from the uterus. One key symptom of placental abruption is dark red vaginal bleeding, which requires immediate notification of a healthcare professional.
Step-by-step explanation:
Placental abruption refers to the separation of the placenta from the wall of the uterus before delivery. It is a serious complication of pregnancy that can cause heavy bleeding, which is often dark red in color. Therefore, a dark red vaginal bleeding is a key symptom of placental abruption, and it is important to notify a healthcare professional immediately if this occurs.