Relationship of DNA integrity of motile human spermatozoa and ICSI outcome

To understand the role of DFI assessment on the outcome of ICSI cycles, we measured DFI of solely motile spermatozoa present in an ejaculate. By different selection methods, we enriched motile spermatozoa where DNA integrity was assessed. A score taking into consideration the fragmentation rate of the motile fraction was built and correlated to clinical outcome. Semen samples were subjected to a triple layer density gradient to enrich the motile sperm fraction. To ensure 100% motile sperm isolation, individual cells were picked up by a microtool. TUNEL, SCD and SCSA were performed on all specimens. Then the DFI of unselected, enriched, and completely motile spermatozoa were compared to a control in relation to the clinical outcome. To normalize the DFI, we generated a score generated by the calculation of: initial DFI x predetermined constant x motility. The normalized DFI values (mDFI) were then assessed for clinical outcome. A total 130 couples were included with a mean male age of 39.9±6 yrs and female of 37.6±4 yrs. When DFI was plotted against sperm concentration and morphology, no difference was observed while when it was evaluated in relation to motility, a significant inverse relationship was seen (P<0.0001). No correlation was observed between the normalized DFI and fertilization (72.7%) nor clinical pregnancy (31.3%) rates. The mDFI between 0-3% (n=113) had a pregnancy rate of 37.2%. When the mDFI greater than 3% (n=37) the pregnancy rate varied greatly with an average of 24.3%. This study indicates that the DFI inversely correlates with sperm motility. The normalized DFI of up to 3% was associated with consistently high pregnancy rates. However, for mDFI greater than 3% chances of pregnancies were impaired. This indicated that the unpredictability of DFI and ICSI conception outcome need to be corrected because ICSI favors morphologically normal and motile spermatozoa.