Effect of incubation and analysis temperatures on sperm kinematics and morphometrics during human semen analysis

Introduction: Human semen analysis must be performed after the liquefaction of the ejaculate. This takes place about 30 min after ejaculation and samples must be maintained in the lab during this time. The temperatures for this incubation and the final analysis of motility are crucial but seldom taken into account. This study aims to examine the effect of these temperatures on various sperm parameters both manually (sperm count, motility, morphology, viability, chromatin condensation and maturation and DNA fragmentation) and CASA (kinematics and morphometrics, using an ISAS®v1 CASA-Mot and CASA-Morph systems, respectively) analyzed. Methods: Seminal samples from thirteen donors were incubated for 10 min at 37 °C followed by additional 20 min at either room temperature (RT, 23 °C) or 37 °C and then examined following WHO 2010 criteria. Results: The data obtained show that there were no significant differences (P > 0.05) in the subjective sperm quality parameters with incubation temperature. On the other hand, the head sperm morphometric parameters were significantly higher after room temperature incubation showing, in addition, lower ellipticity (P < 0.05). Furthermore, kinematic parameters were evaluated both at RT and 37 °C for the two incubation temperatures. In general, the four temperature combinations showed that kinematic parameters followed this order: RT-RT<RT-37<37-37<37-RT (incubation and analysis temperatures respectively). Conclusions: Our results showed that temperature control during both incubation and analysis is needed for accurate semen analysis, recommending the use of 37 °C during the entire process.