There can be a number of things covered by the phrase "gone bad", ranging from phlebitis (inflammation of the vein) to infiltration (where the catheter becomes

There can be a number of things covered by the phrase "gone bad", ranging from phlebitis (inflammation of the vein) to infiltration (where the catheter becomes dislodged from the vein (or pokes through it)) and the IV fluid leaks into the surrounding tissue.