I know absolutely nothing at all about storing donated blood, but reading some threads made me curious.
I read that blood can only be stored for 6 weeks… is this true? If so, what happens after that time that renders the blood useless? Or, in other words, why is blood only good for 6 weeks?
How do they discard “expired” blood?
Are there other options available for blood storage? I know that cryogenics offers a longer storage term, but is that a practical solution? Cost effective?
Yes, blood is discarded after 35-42 days, according to the Red Cross. I’m not really sure why, but I’d guess that the cells begin to break down (red blood cells don’t really have that long a lifespan within your body, either). Plasma, which is the part of blood other than cells, can be stored for much longer IIRC.
They can freeze it, but it’s really expensive (they need to add special chemicals to prevent the cells from being destroyed by ice crystals forming, and then remove these chemicals before transfusing them). I think that they only do it in the case of certain very very rare blood types that they can’t be sure of always receiving a supply of within every 35-42 days.
Red blood cells have to be alive to function and the solutions inside the collection bags vary in the amount of time they can keep the blood cells alive. Plasma is frozen after separation from the rbcs and is good for a year after collection. Expired blood cells can be treated as GilaB mentioned by placing them in glycerol suspension and freezing but it does cost a bit more. At our local blood center it is usually done with donor units with rare phenotypes and also with O negative units because they can be transfused to anyone regardless of the recipient’s type. Frozen units are handy to have when the supply of fresh blood is not sufficient which seems to happen more often in recent years. Frozen units have a life of ten years, however, once thawed and washed to remove the glycerol the units expire within twenty-four hours.
Our hospital returns all expired units to the blood center so I’m not too sure what they do with the ones they don’t freeze.