Intra-individual variation in sperm chromatin structure assay parameters in men from infertile couples: Clinical implications

Background: Sperm DNA integrity is an important factor in the prognosis of male fertility. In this study, we investigated intra-individual variation of sperm chromatin structure assay (SCSA) parameters in infertility patients undergoing assisted reproductive techniques (ARTs). Methods: Retrospective study of 282 consecutive patients referred for ART [intrauterine insemination (IUI), IVF or ICSI] with repeated (between 2 and 5) SCSA measurements. Results: Mean coefficient of variation (CV) of DNA Fragmentation Index (DFI) for repeated SCSA measurements was 29%. A high proportion [37%; 95% confidence interval (CI): 27%, 49%] of patients with DFI >30% in the first test had DFI <30% in the second test. Also, a considerable proportion (27%; 95% CI : 16%, 40%) of patients with 21-30% DFI values in the first test had DFI >30% in the second test. Conclusions: Intra-individual variability in DFI is significant, therefore repeated SCSA measurements are recommended. The biological mechanisms behind these variations remain to be elucidated.