Subchorionic Hematoma at 15.4 weeks along? 7cm please help?

Has anyone else had a subchorionic hematoma at or around 15 weeks?? I am told it means that there is a blood clot in the area of the placenta that has torn away from the uterine wall and that needs to drain before the placenta can reattach....can you give me more details? I go see a specialist at Spectrum Health in GR on next Wed. and my ob this fri....my baby's heartbeat is 150 and measures correct gestation.....the tear is 7 cm....can you give me chances of survival for my baby? There is currently no bleeding or cramping.