counterdrain

Noun

 * 1) A drain at the foot of the embankment of a canal or watercourse, for carrying off the water that may soak through.
 * 2)  An inserted device or other means by which excess fluid is drained off from a part of the body in which it accumulates.

Verb

 * 1)  To drain off excess fluid from a part of the body in which it accumulates.