P-075 Comparison of sperm retrieval efficiency by three cryopreservation techniques using two commercial freezing media in patients with oligozoospermia
Authors: Morales A , Sordia-Hernandez L.H , Oceguera-Palao L.C , Garcia-Luna S.M , Valdes-Martinez O.H , Villarreal-Pineda L , Guzman-Lopez A 
Published: June 2022

Abstract

Study question
Which cryopreservation method and commercial freezing media offer a higher efficiency of sperm retrieval in patients with oligozoospermia?

Summary answer
In patients with oligozoospermia, higher sperm retrieval was observed when using the slow freezing technique regardless of the commercial freezing medium used.

What is known already
Cryopreservation is a process that involves the use of low temperatures to preserve cell structure and function, reducing metabolic activity [1]. Until now, the cryopreservation of sperm has not provided complete protection, since motility decreases by half and even more in infertile patients [2]. Previous publications have reported a deleterious effect when using the slow freezing method, having a higher impact in samples with severe oligoasthenoteratozoospermia or alterations in quantity, motility, and morphology than in normozoospermic samples [3]. Additionally, vitrification has been compared with slow protocols, finding conflicting results while others have reported that these techniques are comparable [4].

Study design, size, duration
We conducted a pilot, prospective and comparative study on 20 patients with oligospermia that attended the Centro Universitario de Medicina Reproductiva of the Hospital Universitario “Dr. José Eleuterio González” from July to October of 2021.

Participants/materials, setting, methods
We included 20 men with oligozoospermia. We compared slow freezing, conventional, and droplet vitrification with two commercial freezing mediums. For which, 1 mL of the semen sample was divided into 2 aliquots. Each of the two freezing media was added at 1:1 ratio into a semen aliquot and later, 300 ul were used to cryopreserve with each of the techniques and subsequently were thawed and assessed for sperm recovery efficiency.

Main results and the role of chance
A total of 20 samples were evaluated. The patients had the diagnosis of oligozoospermia at the moment of the evaluation. When using the Freezing medium TYB (Irvine Scientific), the slow freezing method had a statistically significant higher sperm recovery than the vitrification techniques. Accordingly, there was no difference between standard and droplet vitrification.
When using the Sperm Freezing Medium (InVitro Care, Inc) no statistical difference in sperm recovery was observed for any of the three assessed freezing methods.
Interestingly, with the slow freezing technique, no difference in recovery efficiency was observed regardless of the commercial freezing medium used. Our preliminary findings, highlight the use of the slow freezing technique.

Limitations, reasons for caution
We conducted a pilot study that included 20 patients with oligozoospermia. Therefore, special caution must be taken due to the limited number of patients. Nevertheless, our results showed positive results for the use of the slow freezing method, which has been discontinued possibly by a detrimental effect.

Wider implications of the findings
The slow freezing method for sperm preservation contrasts with what has been used lately and offers patients with poor semen parameters for instance oncologic patients a chance to maintain their reproductive potential

Trial registration number
not applicable