I donated blood on 10/5.  Never before has this happened in my 17 yrs of donating blood, but the blood stopped flowing.  The tech removed the needle because my arm started to swell.  Friday 10/7 I had a small bruise, the swelling was still there.  Saturday 10/8, I had purplish-black marks spreading down my arm, as well as reddish marks on my elbow, which feels like a bruised bone.  Again, swelling still there.  Is this something I should be concerned about?  Why did I bruise worse, 4 days after the fact?
Hi, first don't worry. it's not the big problem. Sometimes it happens.  Due to some technical problems at time of donating blood needle might sleep outside the vein. So blood flow is stopped. And due to some blood goes outside the vein it leads hematoma formation and swelling. It produces Bruce. Bruce will change in color and after some time it will fade itself. Just apply some ice massage on that.no any other treatments is required. don't worry it will cure by itself.