RESUMO
OBJECTIVE: To study the relationship of sperm motion characteristics, sperm morphology, and hypo-osmotic swelling test with fertilization rates in vitro. DESIGN: Computer-assisted measures of fresh seminal and processed sperm preparations, sperm morphology, and hypo-osmotic swelling test results were assessed for predicting fertilization by step-wise regression analysis. SETTINGS: In vitro fertilization laboratory, department of infertility management, university affiliated-hospital. INTERVENTIONS: None. PATIENTS: One hundred and two couples who underwent IVF were studied. MAIN OUTCOME MEASURES: Computer-assisted sperm motion variables in semen and following semen processing in capacitating media; hypo-osmotic swelling of sperm tails before and after semen processing; morphology of sperm before and after processing; fertilization of oocytes as evidenced by presence of two pronuclei as the end point. RESULTS: Various sperm motion parameters, hypo-osmotic swelling test results, and normal morphology of sperm were directly correlated to fertilization as judged by the Karl-Pearsons test. However, in step-wise regression analysis, normal morphology of sperm from seminal fraction exhibited 61% correlation with fertilization rates (P < .001). In step 2, normal morphology along with percent motility exhibited a 64% correlation with fertilization rates (P < .001). In step 3, normal morphology, percent motility, and linearity showed a 67% correlation with fertilization rates (P < .001). The hypo-osmotic swelling test did not predict fertilization rates (regression coefficient = 0.066, P = 0.474). In the processed sample preparations, normal sperm morphology showed a 72% correlation with fertilization rate (P < .001). In step 2, normal morphology along with curvilinear velocity exhibited a 77% correlation with fertilization rates (P < .001). In step 3, normal morphology, curvilinear velocity, and average path velocity showed a 79% correlation with fertilization rates (P < .001). The hypo-osmotic swelling test did not predict fertilization rates (regression coefficient = 0.076, P = 0.512). CONCLUSIONS: Morphology of sperm and computer-assisted sperm motion variables, such as motility, linearity, curvilinear velocity, and average path velocity, may serve as prognostic indicators for fertilization potential of sperm. The hypo-osmotic swelling test may describe only physiological intactness, rather than the fertilization potential of sperm. The results suggest that objective analysis of sperm motion characteristics and precise sperm morphology may form a first, and obligatory, step for critical evaluation of patients before they start IVF treatment.
