Subchorionic hemorrhage, placental abruption, oligohydramnios (20w3d). what does this all mean? is it serious?

Placenta: This means there is a collection of blood between the placenta and the uterine wall- therefore the abruption, the term oligohydramnios basically means low amniotic fluid and can have multiple causes including placenta dysfunction on the side of the mother, of problems with the fetus- problems with the kidneys. Please speak to your physician and seek a referral to a perinatologist.

Wait and watch: 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.