A system and a method for distending a body tissue cavity of a subject by continuous flow irrigation by using two positive displacement pumps, such as peristaltic pumps, one pump on the inflow side and another pump on the outflow side, such that the amplitude of the pressure pulsations created by the positive displacement pumps inside the tissue cavity is substantially dampened to almost negligible levels. The present invention also provides a method of reducing the frequency of the said pressure pulsations. The present invention also provides a method for accurately determining the rate of fluid loss, into the subject's body system, during any endoscopic procedure without utilizing any deficit weight or fluid volume calculation, the same being accomplished by using two fluid flow rate sensors.