[Correlation of sperm DNA fragmentation index with semen parameters]

To explore the relationship of sperm DNA fragmenation index (DFI) with semen parameters and assess its application value in the evaluation of semen quality.

A total of 9 694 semen samples were collected and examined for sperm DFI and high DNA stainability (HDS) by flow cytometry-assisted sperm chromatin structure analysis (SCSA). According to the WHO Laboratory Manual for the Examination and Processing of Human Semen (5th Ed), the samples were divided into a normal group and abnormal groups A (sperm concentration ［SC］: ［11.3－14.0］ ×10⁶/ml, total sperm motility ［TSM］: 30%－39%, progressively motile sperm ［PMS］: 24%－31%), B (SC: ［7.5－11.2］ ×10⁶/ml, TSM: 20%－29%, PMS: 16%－23%), C (SC: ［3.8－7.4］ ×10⁶/ml, TSM: 10%－,19% PMS: 8%－15%) and D (SC: ［0－3.7］×10⁶/ml, TSM: 0－9%, PMS: 0－7%), and also into three sperm DFI groups (DFI <15%, 15%－30% and >30%). The correlation between sperm DFI and seminal parameters was analyzed by Pearson correlation and multiple linear regression analyses.

DFI was dramatically lower in the normal than in the abnormal groups (P < 0.01), and increased in proportion to the decrease of semen parameters in the abnormal groups A, B, C and D (P < 0.01). Pearson correlation analysis showed that DFI was correlated positively with age (r = 0.15, P < 0.01), abstinence time (r = 0.10, P < 0.01), semen volume (r = 0.05, P < 0.01) and HDS (r = 0.15, P < 0.01), but negatively with semen pH (r = －0.06, P < 0.01), SC (r = －0.27, P < 0.01), TSM (r = －0.53, P < 0.01), PMS (r = －0.52, P < 0.01) and morphologically normal sperm (r = －0.16, P < 0.01). Multiple linear regression analysis revealed that TSM, SC, age, abstinence time and semen pH were five important variables associated with DFI, with standardized regression coefficients of －0.47, －0.19, 0.12, 0.07, and －0.04, respectively (all P < 0.01).

There is a moderate correlation between sperm DFI and semen parameters, which can be used synergistically for the assessment of semen quality.