The present invention provides a system and a method for distending a body tissue cavity of a subject by continuous flow irrigation such that minimal or negligible fluid turbulence is present inside the cavity, such that any desired cavity pressure can be created and maintained for any desired outflow rate. 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 or flow rate sensor. 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.