I do not know alot about accretas however I do work in the theatre of a maternity hospital and I have been a part of planned c/s for women who have the accretas. I believe there are different levels of them and I have only seen the more extreme come through our theatre. How it all goes will depend on where the placenta is attached and how deeply it is attached etc. I have seen women who have managed to get through it with a definate bleed during the c/s or birth and who have been fine after blood transfusion etc. BUT I have also seen women who have had no option other than hysterectomy due to the depth of the placental attachment.
I would be asking many questions of your OBGYN and getting as much information as possible so you can be as informed as possible when it comes crunch time. If it has been confirmed that you do indeed have an accreta I would also probably be making sure that my OBGYN has experience with it and if not, then i would try my best to find onw that has! just my opinion though....