Isolated teratozoospermia effects on the intracytoplasmic sperm injection (ICSI) outcome

Abstract

OBJECTIVE: Some studies suggest that sperm morphology may not be critical for ICSI outcomes. Yet other authors imply that sperm morphology is an important predictor of fertilization and embryo development in assisted reproduction treatment cycles. The aim of this study was to analyse the influence of sperm morphology (isolated factor) on fertilization rates and embryo quality in ICSI cycles. DESIGN: Retrospective. MATERIALS AND METHODS: The study included 64 couples. Semen samples were collected on the day of oocyte retrieval, analysed according to the World Health Organization criteria, and their morphology studied according to Kruger's strict criteria. Inclusion criteria were sperm concentration ≥ 20x106 and A+B motility ≥ 25%. Women exclusion criteria: older than 35 or diagnosed with polycystic ovarian or endometriosis. Ovarian stimulation was performed by long protocol. HCG was administered when at least 3 follicles had reached 19mm in diameter. All M2 eggs were injected 4 hours after oocyte retrieval. Fertilization and embryo development were assessed at 20h, 44h and 68h after ICSI. Embryo transfer was performed on day 2 or 3. Patients were divided according to sperm morphology into G1 (< 4 normal cells), G2 (between 4 and 8) and G3 (≥ 9). Statistical analyses used one-Way ANOVA or the Fisher's exact Tests at the level of P<0.05. RESULTS: The number of patients in G1, G2 and G3 were 10, 17 and 37, respectively. Difference in the mean age of female patients across all groups was not statistically significant (NS). Fertilization rates in G1, G2, and G3 were 85%, 90% and 85%, respectively (NS). Embryo quality was divided into A embryos: 58.3%, 43.7%, 53.5% (NS) and B embryos: 36.5%, 35.7%, 33.6% in G1, G2 and G3, respectively (NS). The average of embryos transferred in each group was not significant. Pregnancy rates were 80%; 76% and 54% in G1, G2 and G3, respectively (NS). CONCLUSIONS: Our study suggests that there is no relation between sperm morphology alterations and in fertilization, embryo quality and pregnancy rates. Regardless of a sperm's morphological abnormalities, ICSI outcomes are very similar when sperm concentration and motility are above a certain threshold. We may hypothesize that the discontinuous density gradient treatment of the semen sample and the embryologist's experience in selecting the best sperm cells to be injected by ICSI may contribute to the achievement of high success rates. These findings may carry important diagnostic value when advising patients on IVF treatment.