There was a study done a couple of years back that showed that stored blood started to become less effective after about 21 days. http://well.blogs.nytimes.com

There was a study done a couple of years back that showed that stored blood started to become less effective after about 21 days. http://well.blogs.nytimes.com/2013/03/11/the-shelf-life-of-donor-blood/?_r=0 http://well.blogs.nytimes.com/2013/03/11/the-shelf-life-of-d...