Prediction of unexpectedly poor fertilization and pregnancy outcome using the strict criteria for sperm morphology before and after sperm separation in IVF-ET

This study was performed to investigate if unexpectedly poor fertilization and in-vitro fertilization (IVF) outcome could be predicted using sperm mor phology as diagnosed by the strict criteria. Sperm morphology was assessed in 137 IVF-ET cycles with at least three oocytes collected. The lowest amou nt of normal forms was 5% in 137 samples, indicating there were no patients belonging to 'poor prognosis' (<5% normal forms). Treatment using intracyt oplasmic sperm injection (ICSI) was also excluded. Before sperm separation by the swim-up method, sperm morphology demonstrated a significant correlat ion with the fertilization rate (p < 0.0001). The fertilization rate (80.5% ) in 110 'normal' samples (>14% normal forms) was significantly higher (p < 0.01) than that (55.4%) in 27 samples with 'good prognosis' (those with 5- 14% normal forms). No embryo was available for transfer (ET) in 4 (3.6%) of 110 'normal' cycles and in 3 (11.1%) of 27 'good prognosis' cycles (not si gnificant). Fresh ET was intentionally cancelled to avoid severe ovarian hy perstimulation syndrome (OHSS) in six of 110 'normal' cycles as well as in one of 27 'good prognosis' cycles. The pregnancy rate per ET was 31.0% (31/ 100) in the former group, while it was 26.1% (6/23) in the latter group. Th ere was no difference between the two groups. In the post swim-up evaluatio n of sperm characteristics, morphology was significantly correlated with th e fertilization rate in IVF-ET (p < 0.05) while other sperm parameters were not. When the cut off level for the post swim-up sperm morphology was set at 25%, there was a significant difference in the fertilization rates betwe en patients (78.6%) with post-swim-up >25% and those (55.0%) with post-swim -up less than or equal to 25% (p < 0.01). Taken together, a relative indica tion for ICSI using sperm morphology before and after swim-up was establish ed. Category A includes <less than or equal to>14% normal forms in the ejac ulate and post-swim-up less than or equal to 25%, while Category B includes less than or equal to 14% in the ejaculate and post-swim-up >25%. There wa s a significant difference in the fertlization rates between patients (47.2 %) in Category A and those (60.2%) in Category B (p < 0.05). The clinical p regnancy rate was 11.1% for patients in Category A compared with 35.7% for patients in Category B. However, there was no significant difference betwee n the two categories. These results indicate that the strict criteria provi de a reliable estimation of the fertilizing ability of human spermatozoa. I CSI might be considered in Category A patients to avoid poor fertilization and pregnancy outcome.