Had to get an iv twice in the same arm but with problems both times. what is going on?

Anatomy?: Venipuncture can be difficult to achieve due to various reasons. The veins may be small in diameter; they may be 'mobile' and difficult to penetrate as they move away when an attempt is made; there may be a large layer of subcutaneous fat that makes them hard to locate; or, they may be sclerosed or thrombotic due to previous attempts at venipuncture.