Why is transfused blood discarded after about 6 weeks of storage?

A) It cannot bind to oxygen anymore.
B) It becomes too thick.
C) The BPG levels are too low for adequate release of oxygen to tissues.
D) The percent oxygen saturation is too low.

The primary reason transfused blood is discarded after about 6 weeks of storage is because the levels of 2,3-bisphosphoglycerate (2,3-BPG) decrease over time in stored blood. 2,3-BPG plays a crucial role in facilitating the release of oxygen from hemoglobin to the tissues. As 2,3-BPG levels drop, the hemoglobin holds onto oxygen more tightly, and less oxygen is released to the tissues, making the blood less effective for transfusion purposes.