Our Blood Bank discontinued this practice approximately 10 years ago. We were also advised by our billing team that if we retested in house it was "double billing" and the charges may drop on a bill but we would never be reimbursed for the testing. kirkaw has outlined the AABB guidelines and I bet if you did a cost analysis on this, include the tech time, reagents etc, you would see a huge savings to your BB with no compromise to the quality of pt care.