We have recently began doing post-thaw testing and comparing it to the fresh testing, however, we are performing viable CD34 % recovery post testing. We are using a flow lab that tests for viable CD34 using 7-AAD and single platform methodology so I get comparable absolute CD34 values both fresh and post thaw. We have set a limit of 50% recovery, or we will alert physician of possible poor/sluggish engraftment outcomes. We also calculate the dose of viable CD34 cells/Kg after freezing as well, so the physician has that to look at too. We report the post freeze viability on our reports for information, but have no standard or cut-off limits set. Since this is a viability for all cells in the product (not necessarily CD34 cells), you could get very poor viability just because you have a high granulocyte percentage which died during the freeze but your CD34 cells are fine. That's why we chose to to use CD34 viable recovery. There are a lot of excellent articles that can be review on this subject on the internet. Dr. Rob Sutherland has put out quite a bit of research on this. Good luck!