 It is assumed that the incidence of bleeding from randomization to Day 7 or discharge, whichever earlier, is 10 for the control no transfusion group and 5 for the intervention transfusion group. With 1:1 allocation ratio, to attain 80 power and one-sided 5 type I error rate, the required number of subjects in each arm is 382 by a Chi-square test with Yates continuity correction. If a drop-out rate of 5 is allowed, the required number increases to approximately 400 per arm. 