Abstract: The downstream end section of a transporting lumen (4) for the irrigating fluid is constructed as a nozzle (14), which directs a strong, sharp jet over a free segment (130) into the inlet (16) of a discharging lumen (6). The irrigating fluid jet produces a suction effect, by means of which it aspirates the material from the treated organ (8) and discharges it through the discharging lumen (6). To intensify the suction effect of the irrigating fluid jet, the discharging lumen, when viewed from its inlet (16), consecutively contains the following elements: a mixing tube (18), a diffuser (20) and a discharging duct (22).