Fluid management system and methods

A hysteroscopic fluid management system includes a saline source with an electrolyte concentration, at least one pressure mechanism for circulating saline to and from a targeted site and through a filter having filter characteristics back to the source, and a controller. The controller provides a saline inflow in a first flow path to the site and a saline outflow in a second flow path from the site through the filter and back to the source at a controlled flow rate. A diagnostic or therapeutic procedure is performed at the site in the presence of the saline. The filter characteristics and the controlled flow rate are selected to (1) cause substantially no change in the electrolyte concentration in the saline, (2) to prevent hemolysis of greater than 5% of filtered red blood cells exposed to the saline, and/or (3) to minimize effect on prothrombin time of plasma exposed to the filter.