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J Hum Reprod Sci. 2019 Apr-Jun;12(2):150-155. doi: 10.4103/jhrs.JHRS_154_18.

Comparison of Conventional Slow Freeze versus Permeable Cryoprotectant-Free Vitrification of Abnormal Semen Sample: A Randomized Controlled Trial.

Author information

Department of Reproductive Medicine, Reproductive Medicine Unit, Christian Medical College and Hospital, Vellore, Tamil Nadu, India.



The cryopreservation of semen samples by slow freezing remains as standard protocol. Recently, vitrification of spermatozoa was successfully reported with superior outcome. Till date, there is no randomized trial comparing the two different protocols.


The aim of the present study is to evaluate the slow freezing with vitrification of the subfertile men spermatozoa to evaluate the progressive motility, vitality, and chromatin integrity.


The study was conducted at University teaching hospital.


Study design involves randomized control trial.

Materials and Methods:

Twenty subfertile men with semen characteristics of severe oligoasthenozoospermia (SOA) and very SOA (VSOA) randomized to undergo slow freezing and vitrification protocol and cryopreserved at 1-month and 6-month storage interval, postthawed or warmed, samples were assessed for progressive motility, vitality, and hyaluronan binding. SPSS version 14 software was used for statistical analysis.


The SOA samples at 1 month revealed significantly higher motility (42% [22%-74%] vs. 7% [1%-13%]; P = 0.015) and vitality (57% [45%-78%] vs. 34.5% [27-42]; P < 0.001) following vitrification compared to slow-freeze method. For Very severe oligoasthenozoospermia (VSOA), the motility was significantly higher following vitrification (14.5% [2%-32%] vs. 2.5% [0%-4%]; P = 0.007). At 6 months, no statistically significant difference in motility was found between the two groups for Severe Oligoasthenozoospermia (SOA) samples (27% [13%-62%] vs. 8% [0%-11%]; P = 0.066), but motility was significantly higher following vitrification for VSOA samples (12.5% [3%-32%] vs. 2% [1%-5%]; P = 0.019). The hyaluronan-binding assay was comparable in both the groups at 6 months.


The current study found the vitrification method involving the use of only nonpermeable cryoprotectants for cryopreservation of abnormal semen sample to be an effective alternative to the conventional slow-freeze technique.


Cryopreservation of spermatozoa; slow freezing; vitrification

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