Human pyriform sperm heads in infertile men and assisted reproductive technology outcomes: a retrospective cohort study based on propensity score matching

This study explores the effect of pyriform sperm heads on basic semen parameters, advanced sperm functions, and assisted reproductive technology outcomes. From 2300 patients with pyriform sperm heads in semen, a cohort of 59 couples from the Andrology Clinic of West China Second University Hospital (Sichuan University, Chengdu, China) between January 2022 and July 2024 undergoing assisted reproductive technology were studied. After 108 cycles with 81 embryos transferred, 37 couples achieved clinical pregnancy. Sperm concentration, percentage vitality, total motility, normal morphology, nuclear maturity, acrosomal integrity, acrosome reaction, and mitochondrial membrane potential were significantly lower in the pyriform sperm head group than those in the control group by propensity score matching (all P < 0.05). Non-progressive motility, immotile spermatozoa, the teratozoospermia, sperm deformity, DNA fragmentation index, and DNA stainability were higher in the pyriform sperm head group than those in the control group after propensity score matching (all P < 0.05). Nine morphometric parameters from 2805 typical pyriform sperm heads were evaluated. Cut-off values for predictive diagnostic use of 24.0%, 31.6%, 29.8%, 16.1%, 17.3%, 22.1%, and 9.2% were proposed for the proportion of pyriform sperm heads in seminal samples with abnormal DNA fragmentation index, high DNA stainability, sperm nuclear maturity, sperm acrosome integrity, acrosome reaction, acrosin activity, and mitochondrial membrane potential, respectively. High-quality embryos (35.2% vs 16.8%), clinical pregnancy (46.2% vs 43.8%), and live birth rates (21.5% vs 18.8%) were higher of spermatozoa from samples with a low proportion of pyriform sperm heads (≤38.5%) than with a high proportion of pyriform spermatozoa (>38.5%). The percentage of pyriform sperm heads could be introduced as a diagnostic evaluation parameter before treatment of sperm function and assisted reproductive technology.