A system for distending body tissue cavities of subjects by continuous flow irrigation during endoscopic procedures, the system including: a fluid source reservoir containing a non viscous physiologic fluid meant for cavity distension; a fluid supply conduit tube connecting the fluid source reservoir to an inlet port of a variable speed positive displacement inflow pump and an outlet port of the said inflow pump being connectable to an inflow port of an endoscope instrument through an inflow tube for pumping the fluid at a controlled flow rate into the cavity, the flow rate of the said inflow pump being termed as the inflow rate; an inflow pressure transducer being located anywhere in the inflow tube between the outlet port of the inflow pump and the inflow port of the endoscope; an outflow port of the endoscope being connectable to a waste fluid collecting container via a waste fluid carrying tube, and characterized in that an active inflow pressure pulsation dampening means is connected to the inflow tube for dampening the pressure pulsations inside the cavity created by the positive displacement inflow pump.