Embryo selection for transfer based only on pronuclear parameters alone but not in combination with day-3 embryo evaluation results in higher pregnancy and implantation rates.

Abstract

Objective: Different studies have shown a relationship between various aspects of two-pronuclear (2-PN) morphology and the developmental capacity of embryos. However, it is not yet clarified whether pronuclear parameters can also predict the implantation potential of the developing embryos. The purpose of the present study, therefore, was to investigate the predictive value of pronuclear parameters on pregnancy and implantation rates. Design: A prospective and randomized study involving 290 ICSI-IVF patients. Embryos of 98 patients were selected for embryo transfer (ET) only on the bases of day-3 morphological evaluation. Embryos of 95 patients for ET were selected only on the bases of 2-PN evaluation while embryos of 97 patients were selected taking into account both the 2-PN and the day-3 morphological evaluation. Materials/Methods: Controlled ovarian hyperstimulation was carried out using the GnRHa (leuprolide acetate) long protocol and recombinant FSH in combination with hCG. Oocytes and embryos were cultured in groups using IVF-20 medium (Vitrolife). Evaluation of 2-PN stage was performed 15 to 17 hours after ICSI. Equal sized and centrally located pronuclei with polarized nucleoli (minimum 5 and maximum 18 in the two pronuclei together with a difference of maximum 4) in both pronuclei were the positive selection criteria at 2-PN stage evaluation. On day 3, embryos with more (and equal sized) blastomeres and with less fragmentation (and preferentially no multinucleation in the cells) were selected whenever possible for ET. In the last group (combination evaluation) 2-PN and day-3 morphological evaluation criteria were taken into account together. Embryo transfer was performed on day 3 using Wallace catheter. Clinical and laboratory data were analyzed and compared using One-way ANOVA or Kruskall-Wallis and the chi-square tests whenever appropriate. Results: There were no significant differences found in any of the clinical or laboratory parameters between the three groups. The most important patients’ parameters and results in the three groups are presented in the table. Implantation and pregnancy rates in the three groups. legendMethod of embryo selection for ETlegendP < 0.05 for clinical pregnancy and implantation rates between group-3 vs. group-1 and group-2.CyclesAge of women (±S.D.)Fertilization % (±S.D.)Embryos transferred (±S.D.)Clinical pregnancies (%)Implantation rateDay 3 morphology9836.3 (6.0)77.6 (20.5)3.6 (1.8)25 (25.5)15.12 PN morphology9536.1 (5.0)72.5 (23.0)3.3 (1.7)22 (23.2)12.12 PN + Day 3 evaluation9736.1 (5.8)72.5 (23.4)3.4 (1.7)38 (39.2)21.1legend P < 0.05 for clinical pregnancy and implantation rates between group-3 vs. group-1 and group-2. Open table in a new tab Conclusions: The results of the present study suggest that 2-PN (pronuclear stage) evaluation to select embryos for transfer is similarly efficient to day-3 morphological evaluation in predicting implantation potential of embryos. However, it is also demonstrated that 2-PN stage parameters are not associated closer than day-3 morphological criteria to predict implantation and pregnancy rates. On the other hand, applying 2-PN evaluation criteria additionally to day-3 morphology scoring to select embryos for transfer results in higher clinical pregnancy and implantation rates.