The present invention provides a system and a method for distending a body tissue cavity of a subject by continuous flow irrigation by using a positive displacement pump, such as a pneumatic pump, on the inflow side and a positive displacement pump, such as a peristaltic pump, on the outflow side, such that the amplitude of the pressure pulsations created by a the two positive displacement pump inside the said tissue cavity is substantially dampened to almost negligible levels. 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. The present invention also provides a system of creating and maintaining any desired pressure in a body tissue cavity for any desired cavity outflow rate. The system and the methods of the present invention described above can be used in any endoscopic procedure requiring continuous flow irrigation few examples of such endoscopic procedures being hysteroscopic surgery, arthroscopic surgery, trans uretheral surgery, endoscopic surgery of the brain and endoscopic surgery of the spine.