An ostomy appliance is described in the form of a controlled discharge device for controlling discharge from the stoma and/or an ostomy pouch for collecting discharged waste. The appliance may include one or more of: an elastomeric stoma seal for providing a seal around or directly against the stoma; a stoma occluder for occluding the stoma without passing internally into the stoma; a peristomal foam wall; a confinement seal for confining at least solid excreta to a confinement region adjacent to the stoma; a stowable collector bag; and interchangeable controlled discharge devices and ostomy pouches. The foam wall may provide a barrier to stool, but allow escape of flatus. The foam wall and/or the stoma occluder and/or the confinement seal may apply a force in a direction to increase the sealing force on the stoma seal.