Sperm head's birefringence: a new criterion for sperm selection

Area of Science:

• Reproductive Medicine
• Andrology
• Microscopy Techniques

Background:

• Sperm quality is crucial for successful fertilization and pregnancy outcomes.
• Intracytoplascial sperm injection (ICSI) is an assisted reproductive technology used to overcome male infertility.
• Novel methods for sperm selection are needed to optimize ICSI efficacy, particularly in cases of severe male factor.

Purpose of the Study:

• To characterize the birefringence of human sperm heads.
• To evaluate the application of polarization microscopy for selecting sperm for ICSI.
• To assess the impact of birefringent sperm selection on ICSI outcomes.

Main Methods:

• Prospective randomized study comparing ICSI with birefringent sperm selection (study group) versus conventional ICSI (control group).
• 112 male patients in the study group and 119 in the control group.
• Evaluation of sperm head birefringence, fertilization, cleavage, pregnancy, implantation, and ongoing implantation rates.

Main Results:

• Birefringent spermatozoa were more prevalent in normospermic samples compared to severe male factor samples.
• Fertilization and cleavage rates did not differ between groups.
• Clinical pregnancy, ongoing pregnancy, and implantation rates were significantly higher in the study group for severe male factor infertility.

Conclusions:

• Sperm head birefringence analysis is a potential diagnostic tool.
• Polarization microscopy offers a novel method for sperm selection in ICSI.
• Birefringent sperm selection shows promise for improving outcomes in severe male infertility.