A device intended to be used to measure the depth of a gastrointestinal stoma, from its opening to its terminus within the body, to help in the selection of an appropriately sized gastrostomy appliance (gastrostomy tube). It is typically in the form of a graduated catheter, intended to be inserted into the stoma, which may include an inflatable balloon at the distal end to secure its position after insertion. This is a single-use device.