A medical device such as a controlled discharge ostomy appliance comprises afluid filled seal for sealing around abody orifice (stoma). The fluid filled seal comprises a fluid chamberincluding a fluid impermeable membrane that forms a movablewall of the fluid chamber, one or more ports communicating with the chamber；and resilient foam disposed within the fluid chamber.The foam tends to expand the chamber to seal against the body. The portcontrols the inlet and exhaust of fluid from the chamber, inresponse to movement of the body away from, or towards, the seal.
