A surgical cannula assembly, comprising: an elongated cannula member having proximal and distal portions (14a, 14b) and defining a longitudinal passageway and a longitudinal axis ("X"); a first expandable member mounted to the proximal portion of the cannula member; a second expandable member mounted to the distal portion of the cannula member and being in fluid communication with the first expandable member, wherein each of the first and second expandable members defines a cavity (38a, 38b) therein; and a fluid-transfer assembly including: a proximal flange coupled to the proximal portion of the cannula member; and a distal flange coupled to the proximal portion of the cannula member, wherein the first expandable member is disposed between the proximal and distal flanges such that movement of at least one of the proximal or distal flanges along the cannula member adjusts a pressure applied by the proximal and distal flanges on the first expandable member to transfer an inflation medium between the first and second expandable members; characterised in that the surgical cannula assembly further comprises an elongated sleeve interconnecting the first and second expandable members, the sleeve disposed about the cannula member and defining a longitudinal channel in fluid communication with the cavity of each of the first and second expandable members, wherein the first and second expandable members (20a, 20b) are monolithically formed with respective proximal and distal portions (16a, 16b) of the sleeve. an elongated cannula member having proximal and distal portions (14a, 14b) and defining a longitudinal passageway and a longitudinal axis ("X"); a first expandable member mounted to the proximal portion of the cannula member; a second expandable member mounted to the distal portion of the cannula member and being in fluid communication with the first expandable member, wherein each of the first and second expandable members defines a cavity (38a, 38b) therein; and a fluid-transfer assembly including: a proximal flange coupled to the proximal portion of the cannula member; and a distal flange coupled to the proximal portion of the cannula member, wherein the first expandable member is disposed between the proximal and distal flanges such that movement of at least one of the proximal or distal flanges along the cannula member adjusts a pressure applied by the proximal and distal flanges on the first expandable member to transfer an inflation medium between the first and second expandable members; a proximal flange coupled to the proximal portion of the cannula member; and a distal flange coupled to the proximal portion of the cannula member, wherein the first expandable member is disposed between the proximal and distal flanges such that movement of at least one of the proximal or distal flanges along the cannula member adjusts a pressure applied by the proximal and distal flanges on the first expandable member to transfer an inflation medium between the first and second expandable members; characterised in that the surgical cannula assembly further comprises an elongated sleeve interconnecting the first and second expandable members, the sleeve disposed about the cannula member and defining a longitudinal channel in fluid communication with the cavity of each of the first and second expandable members, wherein the first and second expandable members (20a, 20b) are monolithically formed with respective proximal and distal portions (16a, 16b) of the sleeve.