Sperm head vacuolization affects clinical outcome in ICSI cycle. A proposal of a cut-off value

To evaluate the relationship between sperm nuclear vacuoles and sperm morphology and to investigate the influence of the rate of spermatozoa with head vacuolization (SVR) in a seminal sample on the clinical outcomes in couples undergoing intracytoplasmic sperm injection.

26 patients undergoing infertility investigations were included and were divided in two groups according to an SVR ≤ 20,28 % (Group A) or > 20,28 % (Group B), and were investigated to verify the influence of SVR on the fertilization rate, embryo quality, pregnancy and implantation rates.

Abnormal spermatozoa with nuclear vacuoles were significantly higher (p < 0.001) than the percentage of normal spermatozoa with nuclear vacuoles. Patients in group A had a percentage of abnormal sperm with nuclear vacuole significantly lower compared to group B (p < 0,001), but there was no difference in the percentage of normal sperm with nuclear vacuoles. Fertilization rates and the number of top quality embryos did not differ between the two groups. The pregnancy and implantation rates were significantly higher in Group A compared to Group B (respectively p < 0,05 and p < 0.001).

For the first time, we propose a cut off value in the proportion of sperms with nuclear vacuolization on the total of sperm in seminal samples, and demonstrate a relationship between SNV and clinical outcomes after ICSI. The SNV rate could be introduced as an easy diagnostic evaluation prior to perform an ICSI cycle.