Abstract: A single instrument is provided for simultaneously enabling fluid inflow, fluid outflow and pressure sensing during endoscopic surgical procedures. The instrument comprises three concentric tubular members, each of which has a distal end and a proximal end and each of which has a port connected to its proximal end for providing access to the interior of the associated tubular member. Each of the tubular members is coaxially aligned with the others and the central most tubular member is adapted to enable an elongated endoscopic instrument to be inserted axially therethrough. The invention also resides in the method of sensing pressure within a body cavity by utilizing such an instrument which enables a user to perform fluid inflow, fluid outflow and pressure sensing simultaneously.