How long can blood be stored for until it's no longer usable is there a length of time after which its stored where it can no longer be transferred into someone? why/why not? thanks
There is a time limit before it starts to go bad, but I don't remember those limits off the top of my head. You could probably find out the information from a site from a blood bank or such. The storage times also differ based on the types of blood. Whole blood has the shortest storage time, while plasma, platelets, etc., last longer.
A unit of whole blood/prepared RBCs could be stored for 21 to 42 days but that depends on the type of anticoagulant-preservative solution you use. You can actually use frozen RBCs up to 10 years after they have been frozen. Platelets usually only last about 5 days if left at room temp and have to be agitated continually.