How Much Blood is Transfused?
That depends on the type of surgery and whether or not there are complications. Typical blood usages might be as follows:

Surgical Procedure	Example of Blood Needs
Liver transplant	40 units of units of red cells, 40 units of fresh frozen plasma
Heart transplant	1-4 units of red cells
Open heart	2-8 units of red cells and 6 units of platelets
Orthopedic	2 units of red cells
Tumor removal	2-3 units of red cells
Prostate cancer	4-6 units of red cells
Hysterectomy with complications	2-4 units of red cells
Aneurysm	6 units of red cells and 4 units of plasma
Bone marrow transplant	1-2 units of red cells per week and 6-8 units of platelets daily for 4-6 weeks
Automobile accident	4-40 units of red cells
Leukemia	6-10 units of platelets per day

Please - be a blood donor!