They include the following: Sperm antibody tests, most commonly the direct immunobead test Sperm viability tests (eg, the hypo-osmotic swelling test, exclusion of a supravital dye from sperm) Sperm DNA fragmentation tests, including the single-cell gel electrophoresis assay (Comet assay) and the terminal deoxynucleotidyl transferase-mediated deoxyuridine triphosphate (dUTP) nick-end labeling assay (TUNEL) The usefulness of these specialized tests is controversial and unproved.