Concordance among sperm deoxyribonucleic acid integrity assays and semen parameters

The sperm chromatin structure assay and TUNEL assay are moderately correlated measures of sperm DNA integrity but often yield conflicting results. The DNA fragmentation index is well correlated with semen analysis parameters, whereas TUNEL is not.

Peter J. Stahl, M.D., Chava Cogan, B.S., Akanksha Mehta, M.D., Alex Bolyakov, M.C.Sc., Darius A. Paduch, M.D., Ph.D., Marc Goldstein, M.D.

Volume 104, Issue 1, Pages 56–61


To assess the concordance of sperm chromatin structure assay (SCSA) results, epifluorescence TUNEL assay results, and standard semen parameters.

Prospective, observational study.

Tertiary referral andrology clinic.

A total of 212 men evaluated for subfertility by a single physician.

Clinical history, physical examination, semen analysis, SCSA, and TUNEL assay.

Main Outcome Measure(s):
Spearman’s rank correlation coefficients (r) between SCSA DNA fragmentation index (DFI), percentage TUNEL-positive sperm, and semen analysis parameters.

There was a positive correlation between SCSA DFI and TUNEL (r = 0.31), but the strength of this correlation was weaker than has previously been reported. The discordance rate between SCSA and TUNEL in classifying patients as normal or abnormal was 86 of 212 (40.6%). The SCSA DFI was moderately negatively correlated with sperm concentration and motility. The TUNEL results were unrelated to standard semen parameters.

The SCSA DFI and percentage TUNEL-positive sperm are moderately correlated measures of sperm DNA integrity but yield different results in a large percentage of patients. The DFI is well-correlated with semen analysis parameters, whereas TUNEL is not. These data indicate that the SCSA and TUNEL assay measure different aspects of sperm DNA integrity and should not be used interchangeably.

  • Sperm DNA testing has emerged as the “next best thing” in qualitative sperm measurement. The result of this article support the idea that the available testing methods TUNEL, COMET and SCSA are not perfect and each result needs to be interpreted with caution. Question for the author: if you can only choose 1 method of testing to counsel patients, which would you pick?

    • Peter Stahl

      Thanks for your comment and question, Mike. I think that you have to base your choice of assay on your particular institution’s experience performing these tests. At Cornell, where I trained, the experience with TUNEL was vast and we had good internal data about the relationship of TUNEL results with reproductive outcomes at our center. Therefore TUNEL was a good choice. At Columbia, where I currently practice, our laboratory doesn’t perform these tests and I therefore preferentially use the SCSA, which is available commercially. I also like the SCSA because it is standardized (due to its commercial nature) and because there is a large amount of published data linking DFI results from the SCSA to natural and assisted reproductive outcomes.

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