A method of determining a pressure of a body cavity with a controller of a fluid management system includes determining a pressure and a volume of a cuff disposed about a collapsible bag, determining a volume of the collapsible bag based on the pressure and the volume of the cuff, and determining a pressure of the collapsible bag based on the volume of the collapsible bag. The method also includes calculating a fluid flow from the collapsible bag into a body cavity from the collapsible bag and determining a pressure of the body cavity based on the fluid flow
