The Shirley wound drain or sump drain is a suction drain with an intake tube that provides air to the bottom of the main tube. This allows a continuous flow of suction so that the tube doesn't get blocked. The Shirley drain is a double-lumen drainage tube intended to aspirate efficiently the contents of a fresh surgical wound. It removes the blood oozing from the walls of the wound cavity before it clots. [1] Modern variations of the Shirley drain continue to be used in hospitals, incorporating flexible medical-grade materials and adjustable suction settings to improve patient comfort and efficiency. [2]