Efficacy of Zona-free Hamster Ova Sperm Penetration Assay ( SPA ) in Evaluation of Fertilization Capacity of Human Spermatozoa

Kim, S H; Kim, M H; Jee, B C; Jung, B J; Kim, H S; Ryu, B Y; Pang, M G; Oh, S K; Suh, C S; Choi, Y M; Kim, J K; Moon, S Y; Lee, J Y

Abstract

The objective of this study was to test the validity of zona-free hamster ova sperm penetration assay (SPA) prospectively as a prognostic indicator of male infertility. Fifty infertile patients undergoing in vitro fertilization and embryo transfer (IVF-ET) were selected and classified as fertile and subfertile groups. The fertile group consisted of 25 men in whom fertility was already identified with pregnancy within 1 year before this study, and the subfertile group consisted of 25 men who had the previous history of fertilization failure or less than 30% fertilization rate without oocyte defects in IVF-ET cycles. The effectiveness of SPA as a prognostic indicator for fertilization capacity of human spermatozoa was evaluated after establishing the normal value in SPA. The results of SPA were significantly different in penetration index (PI) and penetration rate (PR) between two groups. Mean PR was 97.4+/-7.4% in fertile group, and 64.9+/-36.2% in subfertile group (p=0.003), and mean PI was 5.4+/-2.9 in fertile group, and 1.5+/-1.5 in subfertile group (p=0.0001). In evaluating the effectiveness of SPA, ROC curve was used. Among the various thresholds for the prediction of fertilizing ability, PI 3.0 corresponded to the value with higher sensitivity and lower false positve rates, and 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 SPA for the prediction of fertilization capacity was 87.0%, 94.7%, 95.2%, and 85.7%, respectively. To evaluate the clinical validity of SPA, this cut-off point was applied to 299 patients undergoing IVF-ET. The sensitivity, specificity, PPV, and NPV of SPA for the prediction of fertilization capacity in IVF-ET was 93.7%, 93.4%, 98.2%, and 79.2%, respectively. In conclusion, our results clearly show that SPA can be a valuable tool as a prognostic indicator of fertilization capacity of human spermatozoa, and can be also useful in performing IVF-ET in male factor infertile patients.