Blood's Shelf Life May Be as Short as 3 Weeks

First In, First Out
Frank adds that throughout the country, blood bank practices direct "first in, first out" policies, so that the oldest stored blood is used first, "because no one wants the blood to expire." According to rules set by the U.S. Food and Drug Administration, after 42 days, or six weeks after it is donated, blood may not be transfused.

With four to five million patients receiving transfusions in the United States each year, transfusing blood is arguably the most common procedure in healthcare. 

The finding is also worrisome because with many more uses for blood, an aging population more likely to need it and less likely to donate it, putting the nation at risk for even worse blood shortage. Barriers to blood donation include certain medical conditions and prescription drugs.

The finding also could impact where and how blood is transported and marketed. Hospitals may be located significant travel distances from the blood banks that collect and distribute blood.

Damage to Cells
In Frank's experiment, six of the 16 patients received at least five units of blood while 10 received fewer than four.  Frank's team took samples from every bag of blood and then measured the flexibility of the outer membrane of the red cell, and discovered the lack of  "deformability," the ability of the cells to squeeze into small diameter capillaries.

They also measured samples of the patients' blood three days after surgery, and found that the damage had not reversed itself. It appeared the cells would remain dysfunctional.

James AuBuchon, MD, former president of the AABB (formerly the American Association of Blood Banks, says, however,  that the report is not news. "We've known [for decades] that red cells become stiffer. And there are myriad changes that occur during red cell storage; I can probably list 30 of them. But which ones have any clinical impact is not known."