Spermatozoal characteristics from fresh and frozen donor semen and their correlation with fertility outcome after intrauterine insemination

Objective: To determine if conventional sperm parameters, specific characteristics of sperm motion determined by computer-aided semen analysis (CASA); sperm penetration assay (SPA), and/or spontaneous acrosome reaction assay could best predict fertility outcome after intrauterine insemination (IUI) from frozen donor sperm. Design: A retrospective analysis of 2,245 cycles of therapeutic donor IUIs were initially studied; 1,147 cycles that met selection criteria were used in this report. Setting: A university-based assisted reproductive technology center. Patients, Participants: All IUIs were performed on women with documented patency of at least one fallopian tube, ovulatory cycles, and who did not receive human menopausal gonadotropins. Sperm donors had to be used for at least four different recipients (mean of 15) and at least 14 different cycles of insemination (mean of 41). Interventions: None. Main Outcome Measure: Pregnancy. Results: Statistical comparisons were made between donors of different relative fertility by using the Mann-Whitney test, Spearman's rank correlation, and multiple regression analysis. These analyses demonstrated that the most significant predictors of the fertility of frozen-thawed donor sperm were curvilinear velocity, straight line velocity, and the total number of motile sperm inseminated. The number of sperm with spontaneous acrosome reactions negatively correlated with fertility outcome, and SPA provided no predictive value. Conclusions: Our study supports the hypothesis that the study of sperm motion characteristics using CASA after thawing and washing of cryopreserved sperm is a better predictor of fertile outcome after IUI than analysis of fresh semen.