Figure 5.

Comparison of fertilization and clinical pregnancy rates in cases with few spermatozoa identified. In 986 cycles, extremely few spermatozoa were seen after high-speed centrifugation. Samples were searched for injectable spermatozoa in drops under oil for up to several hours by multiple embryologists until all oocytes were injected. Oocytes injected with ejaculate spermatozoa demonstrated a higher fertilization rate compared to those injected with testicular specimen (χ², 2 × 2, 1 df; P < 0.0001). Clinical pregnancy rates remained comparable between the two sperm sources.