If an intravenous (IV) line is left for too long in one spot (such as the back of the hand), the vein may develop a hard bump or knot that persists after the IV line is removed. Sometimes this is referred to as in "infiltration." Some people suggest it may result from formation of scar tissue. It might also occur if the needle hits a valve in the vein.
Treatments to help the knot dissapear include:
1) passage of time
2) do not allow this location to be used again for needle-sticks until the hard spot is gone
3) warm compesses
4) soak in warm water
It should go away within a few weeks.