What is meant by a partial placenta abruption?

Placental detachment: This means that some of the placenta has detached from the uterus with the baby still inside the uterus. As the placenta is the baby's lifeline for oxygen, blood and nutrients, such a complication can prove lethal or severely neurologically noxious to the fetus - unless prompt medical attention is sought and appropriate management instituted on an emergent basis (stat cesarean may be required).

Small section, ltd.: 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.