Comparing Methods for Sperm DNA Fragmentation Detection

Sperm DNA fragmentation (sDF) detection has been proposed as an adjunct of routine semen analysis in the male infertility work up. Unfortunately, the gold standard test to reveal this parameter has not yet established and four different tests are available: (i) SCSA (Sperm Chromatin Structure Assay), detecting the resistance of sperm chromatin to denaturation; (ii) TUNEL (Terminal deoxynucleotidyl transferase dUTP Nick-End Labeling), labelling the 3'OH ends released by single and double DNA breaks; (iii) Alkaline COMET Assay, evidencing the single and double DNA fragments and SCD (Sperm Chromatin Dispersion) test, revealing the inability of DNA fragmented spermatozoa to form a halo around the nuclear core. These tests are different each from the other in many aspects, including the type of revealed damage and the clinical correlates. Another issue is the lack of standardised procedures that yields different values for sDF even using the same test. Protocols suggested by the last version of WHO guideline can be of help, but unfortunately cut-off values were not provided. In conclusion, although detection of sDF has been emerged as a novel clinical parameter, there are several issues still to be fixed in order to facilitate the use in the clinical practice.