The relationship between DNA fragmentation and the intensity of morphologically abnormal human spermatozoa

Abstract

To determine the relationship between teratozoospermia and sperm DNA fragmentation (SDF) in the human ejaculate. This retrospective study included 100 normozoospermic men as a control cohort (abnormal forms >14%), 210 patients with a high level of abnormal forms (≤4%) and 65 patients presenting with a moderate level of abnormal forms (>4% to ≤14%) based on the World Health Organization definitions. Sperm morphology was assessed using bright field microscopy. Sperm DNA fragmentation was assessed using the sperm chromatin dispersion assay. Non-parametric analyses were conducted to examine the relationship between abnormal sperm morphology and sperm DNA fragmentation; receiver operating characteristic (ROC) analyses were conducted to assess sensitivity and specificity of this relationship. A correlation analysis revealed that the higher the proportion of abnormal spermatozoa in the ejaculate, the higher the level of SDF (Spearman's Rho = -0.230; P<0.001). Significant differences in the proportion of SDF were found when all cohorts were compared (P<0.001); these significant differences were also retained when the different cohorts were compared pairwise. ROC analysis showed a moderate but significant predictive value for SDF to differentiate patients with different levels of teratozoospemia. Although analysis of a more continuous range of values for teratozoospermia would help further clarify any causal relationship with SDF, there is clearly a synergistic or coincident affiliation between these variables that needs to be acknowledged by the clinician when interpreting the spermiogram.