I've had some bleeding and back / abdominal pain at 15 weeks pregnant. doctor said it's partial placental abruption. what does this mean?

Tearing away: Think of the placenta as if it is a big pizza,attached on one side to the uterine wall and the side composed of a network of blood vessels that come together as the cord and attaches to baby. Sometimes the placenta moves or migrates a bit, and the attachment can separate in small areas.The process of separating is called abruption.It can be slight and insignificant, or major and a threat.

SmallBleed; WillHeal: Abruption is a bleed from the placenta; a disruption of either the mother or baby's blood supply. Many causes: trauma, high blood pressure, drugs (cocaine), preterm labor, polyhydramnios. Can be very large or very small, so even US can miss a diagnosis. Symptoms: usually preterm contractions, sometimes vaginal bleed. Fetal monitoring is necessary. Wait, watch; abruption can self-heal sometimes.