Diagnostic accuracy of sperm chromatin dispersion test to evaluate sperm deoxyribonucleic acid damage in men with unexplained infertility

Abstract

Objective: To compare the sperm chromatin dispersion (SCD) test and the terminal uridine nick-end labeling (TUNEL) assay for assessment of sperm DNA damage.

Design: Prospective comparative experimental study.

Setting: Andrology laboratory.

Patient(s): Twenty subfertile men with unexplained infertility.

Intervention(s): Sperm DNA damage was determined in the same semen samples using the TUNEL assay with fluorescence microscopy and the SCD test with bright-field microscopy.

Main outcome measure(s): Correlation coefficient and receiver operating characteristic analysis outcomes. The TUNEL assay was used as the reference standard to identify optimal cutoff points for assessing DNA damage by SCD.

Result(s): The SCD test detected a significantly higher proportion of sperm with damaged DNA (20.6% ± 14.0%) than the TUNEL assay (11.5% ± 7.3%). Spearman's rank correlation showed that the methods were not comparable (r = 0.29). Receiver operating characteristic analysis revealed that 15% was the best SCD cutoff point to classify patients within the same levels of DNA fragmentation, normal or abnormal, as determined by the TUNEL assay, with an accuracy of 69%.

Conclusion(s): The SCD test is more sensitive than the TUNEL assay for the assessment of DNA damage in men with unexplained infertility. Although the methods are poorly correlated, SCD may discriminate men with normal and abnormal sperm DNA damage with moderate accuracy when compared with TUNEL. It is important to distinguish between the methods because they differently evaluate sperm DNA damage.

Keywords: ROC curve; Sperm DNA damage; diagnosis; in situ nick-end labeling; sperm chromatin dispersion test.