Unsettling new evidence suggests that blood stored for more than 2 weeks might be less beneficial to recipients recovering from cardiac surgery than is fresher blood. While the study falls short of heralding a wholesale change in blood-banking practices, scientists agree that it exposes the need for a large trial to determine the optimal shelf life of stored blood. The current limit is 42 days.
Laboratory research has indicated that stored blood loses quality over time (SN: 10/27/07, p. 269). But previous studies of patients who received old or new blood proved inconclusive.