An ostomy guide plate (11) is provided 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 (14) in said convex protrusion, wherein the plate is adapted for disposition on the skin of the patient with the aperture positioned over the stoma for assessing the stomal configuration of a patient. A measuring tool (11') may include a plurality of such ostomy guide plates, wherein each plate is provided with at least one distinct dimensional parameter.
