Unfortunately ended up in my local hospital due to tachycardia. Everything was going well with medics attention, just one problem. They asked to take blood for testing etc. Four phials were successfully taken, then off to lab. Quite a while later medic asked if he could take another phial - one lot had clotted before the test had been dealt with! So off went the second phial, later on the poor same medic came along and apologised - 2 of the phials had clotted!! Please, please anyone have answer to this?! I am on Pradaxa, was wondering if the blood once it has been released from the vein/artery does clot a lot quicker due to it being thinned out so much in the system?