Timing of semen cryopreservation: before or after processing?

Abstract

Objective: Seminal cryopreservation causes significant damage to the sperm; therefore, different methods of cryopreservation have been studied. The aim of the study was to compare the effects of density gradient processing and washing/centrifugation with seminal plasma removal for cryopreservation in semen parameters.

Methods: Seminal samples of 26 normozoospermic patients were divided into 3 parts: with seminal plasma; after washing/centrifugation; and after selection through density gradient. The samples were cryopreserved for at least two weeks. Motility, sperm count, morphology and viability were evaluated before cryopreservation and after thawing.

Results: Density gradient processing selected motile and viable sperm with normal morphology in fresh samples (p<0.05). Cryopreservation negatively affected all sperm parameters regardless of the processing performed, and even if the sperm recovery was lower in the density gradient after the thawing, progressive motility, total motility, viability and morphology remained higher (p<0.05).

Conclusion: Cryopreservation significantly compromises sperm parameters (motility, morphology, viability). In normozoospermic patients, the density gradients select better quality spermatozoa compared to other processing methods; this benefit was kept after thawing.