RESUMO
The proportion of male factor infertility due to quantitative and qualitative sperm disorders is approximately 50-60% in infertile couples. In IVF-ET, lower or failed fertilization of oocytes usually results from subnormal count of total motile sperms, but this may occur in infertile couples even with normal sperm count. It has been suggested that some functional defects in sperms are responsible for lower or failed fertilization. Routine semen analysis based on numerical background has limits for the assessment of fertilization capacity of sperm in infertile males, and the andrologic test for the prediction of fertilization capacity must be objective, repeatable, quick, economic, and easily applicable for the clinical settings. The purposes of this study were to develop the analysis method of strict morphology of sperm using the strict criteria as a simple, inexpensive and useful test of sperm fertilization capacity, to establish the normal fertile range and the cut-off value of strict morphology, and to evaluate the validity of strict morphology as a prognostic indicator of fertilization capacity in IVF-ET. In establishing the effectiveness of strict morphology of sperm, ROC curve was used. Among the various thresholds for the prediction of fertilizing ability, normal morphologic value 10.0 corresponding to the value with higher sensitivity and lesser false positive rates was determined as a cut-off value. Using this cut-off point, the sensitivity, specificity, positive predictive value (PPV), and negative predictive value (NPV) of strict morphology for the prediction of fertilization capacity was 73.9%, 81.0%, 80.6%, and 72.7%, respectively. To evaluate the clinical validity of strict morphology as a prognostic indicator of fertilization capacity, this cut-off point was applied to 133 patients undergoing IVF-ET. For the prediction of fertilization rate >30% in IVF-ET, the sensitivity, specificity, PPV, and NPV was 77.3%, 77.8%, 87.2%, and 63.6%, respectively. In conclusion, the strict morphology of sperm is one of the most simple and useful test for the assessment of fertilization capacity of sperm and the prediction of IVF-ET outcomes in infertile couples.