Initial motility and vitality predict the semen quality after long-term cryostorage, even in patients with restricted ejaculate parameters.

Abstract

Background: Cryopreservation of human semen is the cornerstone for preserving male fertility before gonadotoxic therapy or in cases of high variability in semen parameters. This is particular crucial in cases of severe oligoasthenoteratozoospermia (OAT), where diminished sperm counts may compromise planned intracytoplasmic sperm injection (ICSI) procedures. Previous investigations in donor programs have shown long-term storage effects, such as decreased motility in cryopreserved semen samples. However, these studies were based on patients exhibiting normozoospermic semen samples. To date, there has been no comprehensive evaluation of the effect of long-term cryostorage on sperm samples from individuals with compromised semen parameters.

Objectives: The aim of this study was to identify the effect of long-term cryostorage on semen parameters such as motility and vitality. Additionally, we sought to identify variables, which could aid in predicting motility and vitality following the freeze-thaw process.

Patients and methods: Within our center, we have archived sperm samples from 6022 patients cryopreserved between 2001 and 2019. Among these, 293 patients donated their samples for subsequent research following depot termination. We examined semen concentration, motility, morphology, and vitality of spermatozoa thawed after varying storage durations, alongside baseline metrics documented at the time of cryopreservation. Samples were stratified into three cohorts based on storage duration: 2.5 to ≤5 years, > 5 to ≤14 years, and > 14 years.

Results: Our analysis revealed no changes in motility (p = 0.44), vitality (p = 0.08), or morphology (p = 0.44) across the cohorts. Regression analysis demonstrated that initial motility and sperm concentration were significantly associated with post-cryostorage motility, whereas storage duration was not (p = 0.72). Similarly, there was no association between storage duration and post-thaw value 2 vitality (p = 0.64).

Discussion: The initial semen analysis as well as the evaluation of a short-term frozen sample immediately after cryopreservation, appeared to be the most important markers for predicting post-thaw motility and vitality.

Conclusion: Our results demonstrate the reliability of long-term cryostorage of human spermatozoa for fertility preservation, even in individuals with constrained semen quality at the time of cryopreservation.