Specific sperm morphological abnormalities and their functional implications in a cohort of Turkish men from a single-center clinical population

The role of sperm morphology in male fertilization potential remains unclear. This study aimed to evaluate the incidence of specific sperm morphological abnormalities in a cohort of Turkish men attending a single-center infertility clinic and to assess their associations with semen quality and sperm functionality. A total of 2,923 men aged 17–57 years were included in this cross-sectional study. Semen parameters and specific morphological abnormalities in the head, neck-midpiece, tail, and cytoplasmic residue were analyzed according to WHO criteria. Participants were categorized into normal and low semen parameter groups based on sperm count, motility, and normal morphology. Associations between semen parameters and morphological abnormalities were assessed using Spearman correlation and binary logistic regression analyses. Head defects were the most prevalent abnormalities, followed by tail, neck-midpiece, and cytoplasmic residue. Normal sperm morphology and specific abnormalities were significantly associated with semen quality, with normal forms demonstrating the strongest predictive potential. Head defects were primarily associated with teratozoospermia, whereas neck-midpiece and tail defects were linked to motility impairments. Notably, round and tapered heads, bent necks, and coiled or short tails showed the strongest associations with progressive and rapid progressive motility, which are critical determinants of fertilization capacity. Our findings indicate that different categories of sperm abnormalities have distinct predictive potentials for semen quality disorders and suggest that specific defects may arise from disruptions in different stages of sperm morphogenesis.