Baby's fine but I'm bleeding bad...

Jen
I was diagnosed with Placenta Previa on Sunday after a huge gush of blood sent me to the ER...yesterday I followed up with my OB after several more gushes that soaked through a pad, my undies and my pants. Doc said baby is fine for now and to just take it easy.... I have a follow-up appt this Friday. She told me my cervix is closed like it should be. But now that I'm home thinking about this.... how am I bleeding out from the placenta if my cervix is closed??? Maybe I'm not understanding something? Anyone know what I'm missing?