A system (100; 200) for delivering insufflation gas to a body cavity of a patient during an endoscopic surgical procedure, comprising: a) an insufflation conduit for delivering a continuous flow of insufflation gas to the body cavity at a variable flow rate through a flow path that communicates with a pneumatically sealed trocar (131; 231) which prevents over-pressurization of the body cavity; b) an insufflator for driving gas flow through the insufflation conduit at a specified driving pressure, wherein the gas flow rate through the insufflation conduit will vary depending upon body cavity pressure; c) a flow meter communicating with the insufflation conduit and located between the insufflator and the body cavity for continuously measuring gas flow through the insufflation conduit; and d) a processor for determining a body cavity pressure corresponding to a given driving pressure based upon a gas flow measurement from the flow meter, and wherein the system (100; 200) further comprises a driving pressure sensor communicating with the insufflation conduit for providing feedback to the insufflator so that the insufflator maintains the specified driving pressure of insufflation gas to the insufflation conduit, characterized in that the processor is configured to use data for a continuous flow of insufflation gas delivered at a variable flow rate and a specified driving pressure stored in memory in a look up table selected based on known dimensions of a portion of the fluid path to the body cavity for determining the body cavity pressure, and when the dimensions of the portion of the fluid path are unknown, the processor is configured to determine body cavity pressure by taking periodic static pressure measurements from a further pressure sensor located along the flow path, and associating those static pressure measurements with periodic flow measurements taken by the flow meter. a) an insufflation conduit for delivering a continuous flow of insufflation gas to the body cavity at a variable flow rate through a flow path that communicates with a pneumatically sealed trocar (131; 231) which prevents over-pressurization of the body cavity; b) an insufflator for driving gas flow through the insufflation conduit at a specified driving pressure, wherein the gas flow rate through the insufflation conduit will vary depending upon body cavity pressure; c) a flow meter communicating with the insufflation conduit and located between the insufflator and the body cavity for continuously measuring gas flow through the insufflation conduit; and d) a processor for determining a body cavity pressure corresponding to a given driving pressure based upon a gas flow measurement from the flow meter, and wherein the system (100; 200) further comprises a driving pressure sensor communicating with the insufflation conduit for providing feedback to the insufflator so that the insufflator maintains the specified driving pressure of insufflation gas to the insufflation conduit, characterized in that the processor is configured to use data for a continuous flow of insufflation gas delivered at a variable flow rate and a specified driving pressure stored in memory in a look up table selected based on known dimensions of a portion of the fluid path to the body cavity for determining the body cavity pressure, and when the dimensions of the portion of the fluid path are unknown, the processor is configured to determine body cavity pressure by taking periodic static pressure measurements from a further pressure sensor located along the flow path, and associating those static pressure measurements with periodic flow measurements taken by the flow meter. wherein the system (100; 200) further comprises a driving pressure sensor communicating with the insufflation conduit for providing feedback to the insufflator so that the insufflator maintains the specified driving pressure of insufflation gas to the insufflation conduit, characterized in that the processor is configured to use data for a continuous flow of insufflation gas delivered at a variable flow rate and a specified driving pressure stored in memory in a look up table selected based on known dimensions of a portion of the fluid path to the body cavity for determining the body cavity pressure, and when the dimensions of the portion of the fluid path are unknown, the processor is configured to determine body cavity pressure by taking periodic static pressure measurements from a further pressure sensor located along the flow path, and associating those static pressure measurements with periodic flow measurements taken by the flow meter.