Tenderness in i.v area after iv was taken out bruise was there and is now gone cause?

Small trauma: An IV needle inserted through your skin and into your vein was trauma to your body. No way around it, expected, appropriate trauma. The vein may even have a small amount of blood clot or "inflammatory" response as a result of the catheter having been there for hours or days. With time, the bruise and tenderness will resolve, just like most trauma does. Patience + warm washcloth soaks may help.