A convex barrier ring, that includes a generally oval shaped body and tapered peripheral end portions, is provided. In use, the convex barrier ring is sealed against peristomal skin surfaces such that the tapered peripheral end portions are aligned with folds or creases in the skin surfaces to reduce leakage of stomal effluent. The convex barrier can also have an oval stoma-receiving aperture to provide an improved fit for oval or loop stomas.