The present disclosure relates to ostomy appliances and more particularly to an ostomy guide plate for assessing the stomal and/or peristomal configuration of a patient comprising a distal face, a proximal face with a convex protrusion and an aperture in said convex protrusion, wherein the ostomy guide plate is adapted for disposition on the skin of the patient with the aperture positioned over the stoma. The disclosure further relates to a measuring tool comprising a plurality of said ostomy guide plates, wherein each plate is provided with at least one distinct dimensional parameter.
