 The purpose of a drain is to prevent fluid (blood or other) build-up in a closed ("dead") space, which may cause either disruption of the wound and the healing process or become an infected abscess, with either scenario possibly requiring a formal drainage/repair procedure (and possibly another trip to the operating room).The drain is also used to evacuate an internal abscess before surgery when an infection already exists.Clots and other solid matter in the drainage fluid may occlude the tubing, preventing the device from draining properly.