[–] SteelKidney 0 points 1 point 1 point (+1|-0) ago
The more routine, the less likely. Go in for an annual physical, which usually involved bloodwork, and it's likely to get destroyed. Like @Mixplate said, there's literally no room to store that much blood.
On the other hand, if there's a reason to, then yes. Not a medical professional, so I'm just guessing, but I'd expect that if there's something wrong with you that's a good deal less common then your blood is going to get stored and make the rounds through different departments. Possibly even different organizations such as the WHO. Not the band. :)
All that said, your blood is almost certainly destroyed when no longer needed.
[–] 2989699? ago
Samples aren't kept except in extremely rare cases. There are literally thousands of blood samples taken every day and there's no space to store them.
On the other hand, there is this. http://www.nature.com/news/minnesota-starts-to-destroy-stored-blood-spots-1.9971