Search

Reports concerning the benefit of reducing the co-incubation time of gametes in connection with IVF have been conflicting. The present randomized study was undertaken to determine whether a reduced co-incubation time would improve the embryo development and consequently the pregnancy and implantation rates. Oocytes from 87 patients were collected and half the oocytes from each patient (n= 488, group A) were randomized to 2 h incubation and the other half (n= 504, group B) to overnight incubation. The oocytes were then cultured according to our standard procedure. Significant difference (P= 0.02) was observed between the two groups regarding fertilization rate and polyspermy (group A 72.5%, 3% and group B 80.5%, 6% respectively). However, no difference was observed in further development and morphology of the embryos. The two embryos with the best morphological score were selected for transfer. No significant difference was found between the different transfer groups regarding positive serum HCG and implantation rate. Conclusion: The present results and results from previously published studies indicate that the most important factor in connection with the culture method currently used is the amount of sperm added for co-incubation. This should be optimized to reduce the concentration of harmful sperm waste products and create optimal culture conditions.

A total of 340 patients referred for in-vitro fertilization was included in a retrospective, comparative study in which zygotes were studied regarding alignment and polarization of nucleolar precursor bodies (NPB) and also early cleavage in relation to implantation and pregnancy rates for the 680 transferred embryos. At assessment of the pronucleus 18–19 h after sperm injection, NPB were checked for alignment/polarization. Twenty-six hours after sperm insemination the zygotes were assessed for early cleavage. At embryo transfer the two embryos with the best morphological score, irrespective of polarization and early cleavage, were selected for transfer. The overall rate of positive HCG tests 17 days after embryo transfer was 42% and the implantation rate 23%. Fourteen percent of the patients received two embryos with polarized NPB, with a positive HCG test of 51%. Embryo transfer with early-cleaved embryos was carried out in 21% of the cycles, with a pregnancy rate of 45%. Embryos with polarized NPB and/or early cleavage were transferred in 34% of the cycles, with a pregnancy rate of 51%, compared with a pregnancy rate of 38% when none of the embryos fulfilled these criteria (P-value 0.02). In this study the pregnancy rate was significantly higher when one or two embryos were polarized and/or early cleaved. It is concluded that in a cohort of morphologically good embryos, assessment for alignment/polarization of NPB and/or early cleavage can, together with conventional morphological criteria, serve as a simple non-invasive method for selection of embryos with high implantation potential.