Sperm Motility Stability During Long-Term Cryopreservation: A Paired-Sample Study on 101 Fertility Preservation Patients.

BACKGROUND

Uncertainty persists regarding the impact of very long-term liquid nitrogen storage (>10 years) on sperm quality, particularly for oncology patients and those with suboptimal initial semen quality.

OBJECTIVES

To evaluate the impact of storage duration on post-thaw motility parameters and clinical assisted reproductive technologies (ART) utility using a robust paired-sample design.

MATERIALS AND

METHODS

This paired cohort study analyzed 101 semen samples (62 cancer, 39 non-cancer) at two time points: immediately after freezing (T0) and after 2-12 years of storage (T1) in 0.3-mL high-security straws. Total/progressive motility and motile sperm counts (TMSC/PMSC) were compared using random-effects modeling with interaction terms for patient subgroups.

RESULTS

Sperm parameters showed minimal average change over the 2-12-year storage range, with no evidence of differential T0-T1 variation according to initial sperm quality or diagnosis (all interaction p values >0.3). An exploratory analysis of the small 11-12-year subgroup (n = 24; including 21 oncology patients) showed a significant but modest decline in total motility (-3.6%; p < 0.05) and motile counts (TMSC -0.5 M; p < 0.05). Concordance coefficients provided supporting information on relative agreement between T0 and T1 (Lin's > 0.70; p < 0.001), and most samples (84.6% overall, 87.5% in the 11-12-year group) maintained their original ART eligibility (intrauterine insemination [IUI]/in vitro fertilization [IVF]/intracytoplasmic sperm injection [ICSI]).

DISCUSSION AND

CONCLUSION

Human sperm motility showed limited average changes over the 2-12-year storage range. The exploratory findings in the small 11-12-year subgroup, predominantly composed of oncology patients, suggest modest changes with limited impact on ART strategy. These results provide reassuring evidence for long-term counseling in oncofertility and support the clinical management of cryopreserved sperm samples.