Sperm processing by swim-up and density gradient is effective in elimination of sperm with DNA damage
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Updated: May 24, 2026

Sperm Collection of Differential Quality Using Density Gradient Centrifugation
Published on: November 29, 2018
Varshini Jayaraman1, Dinesh Upadhya, Pratap Kumar Narayan
1Division of Reproductive Medicine, Clinical Embryology Laboratory, Kasturba Medical College Manipal University, Manipal 576 104, India. varsh1981@gmail.com
Purpose:
DNA damage may occur during sperm processing, thereby negatively influencing fertilizing ability of the sperm. The present study was designed to compare the effectiveness of gradient and swim-up, either alone or in combination, to eliminate sperm with DNA damage.
Methods:
A total of 51 subjects visiting the University infertility clinic with normozoospermic parameters, oligozoospermia and teratozoospermia were included. Semen characteristics were analysed by standard criteria; Terminal deoxy nucelotidyl transferase mediated dUTP nick end labeling assay was employed for DNA damage assessment.
Results:
The percentage of TUNEL positive sperm after sperm processing was significantly lower in normozoospermic (P < 0.05), oligozoospermic (P < 0.001) and teratozoospermic samples (P < 0.01). No difference was observed in the incidence of TUNEL positive sperm between the various techniques, suggesting that they are comparable.
Conclusions:
Sperm preparation has been found to result in enrichment of sperm with intact chromatin, which is likely to improve the chances of achieving a viable pregnancy.
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