An operating device is provided which includes an instrument insertion conduit, having a distal end connectable to the operating channel input of a handle of an endoscopic probe, the proximal end of the instrument insertion conduit forming an instrument input for the operating device, a suction assembly comprising a suction conduit communicating with the insertion conduit and a control device for selectively connecting the suction conduit to a pump, to suck out fluids through the operating channel, and a connecting conduit putting the suction conduit into communication with the insertion conduit, and the length of which is such that when the operating device is fixed on the handle, the suction control device is positioned close to the control means located in a proximal part of the handle.