I take blood tests quite frequently, and most the time the technicians (Phlebotomists) spend a lot of time searching both my arms for a good vein. I pump my fists, and they smack my arms (and of course there's the typical tourniquet up on the arm), but still not much luck. This has led to inserting the needle in wrong places (ouchy!) and ultimately they end up using butterfly (smaller/for kids) needles. I've constantly been told that my veins are difficult.
However, there's been a few times when the technicians (even the same ones -- so it's not a matter of skill level) are able to insert the needle right away as my veins are prevalent and easy to find.
What are the factors that make veins easy for a blood tests one day, and difficult another day? How can I make it so my veins are easy for the technicians?
Also, are there some people who just have hard/difficult veins for blood tests/Iv's regardless of factors?