TUNEL assay: Establishing a sperm DNA fragmentation cut-off value for Egyptian infertile men

Male factor infertility is responsible for half of all infertility cases. Conventional semen analysis is inadequate to evaluate male fertility. Sperm DNA fragmentation (SDF) test can be done by: direct methods such as Terminal deoxynucleotidyl transferase dUTP Nick-End Labeling (TUNEL) and Comet assay, or indirect like Sperm Chromatin Structure Assay (SCSA) and Sperm Chromatin Dispersion (SCD). TUNEL assay measures both single- and double-strand breaks and is technically less demanding, while SCSA tests for the susceptibility for nuclear DNA denaturation and samples should be sent to the reference lab. Studies showed that a single cut-off value does not fit all. Therefore, this study aimed at establishing a cut-off value to discriminate between fertile and infertile Egyptian men. We enrolled 354 infertile men and 40 proven fertile volunteers.TUNEL assay was performed using Apo-Direct kit and bench top flow cytometer.The calculated SDF cut-off value was 20.3% with a sensitivity of 96.6% and specificity of 87.5%, and the overall accuracy of the test was 95.7%. Sperm DNA fragmentation Test using TUNEL assay is valuable tool for male infertility evaluation, and it assists in offering the best treatment options based on it's results.