Predictive value of sperm morphology and movement characteristics in the outcome of in vitro fertilization of human oocytes

Abstract

One hundred fourteen semen samples from Chinese males were analyzed for routine semen parameters including the semen volume, sperm count, percentage motility, and percentage normal morphology. Of these 114 samples, 54 also had movement characteristics of seminal and swim-up sperm evaluated by the computer image analyzer system (Cellsoft; Cryo Resources Co., New York). All semen samples were subjected to the swim-up procedure to harvest the motile sperm before inseminations of human oocytes. Fertilization was considered to have occurred when at least one oocyte was observed with two or more pronuclei. Semen samples were classified as infertile (0% fertilization rate; N = 32) or fertile (>0% fertilization rate; N = 82) before statistical analyses. There was a significant difference (P < 0.005) in percentage normal morphology of seminal sperm between the fertile (mean ± SE; 67.3 ± 1.2%) and the infertile (59.3 ± 2.2%) samples. The percentage normal morphology of seminal sperm correlated (r = 0.3049; P < 0.002) with the fertilization rate and this parameter was selected by the multivariate stepwise discriminant analysis as the discriminator capable of predicting the fertilization rate with 57.9% accuracy. Statistical analyses of samples where sperm movement was also evaluated demonstrated that there was significant differences (P < 0.01) between the fertile (N = 38) and the infertile (N = 16) samples in percentage normal morphology of seminal sperm (67.8 ± 1.8% vs 56.2 ± 2.6%) and curvilinear velocity of swim-up sperm (89.2 ± 3.5 vs 68.2 ± 7.2 μ/sec.). The fertilization rates correlated with the percentage normal morphology of seminal sperm ( r = 0.3868; P < 0.005) and velocity of swim-up sperm (r = 0.3842; P < 0.005). Multivariate stepwise discriminant analysis demonstrated that these two sperm parameters in combination were capable of predicting the fertilization rate with 74.1% accuracy. Our results indicate that seminal sperm morphology, coupled with computer-assisted image analysis of movement characteristics of swim-up sperm, can help to predict the outcome of in vitro fertilization of human oocytes.