Comparison between three embryo scoring systems as predictive of the outcome of in vitro fertilization - Revista Brasileira de Ginecologia e Obstetrícia

PURPOSE: to evaluate three embryo scoring systems specific for 3-day embryos and to correlate them with positive in vitro fertilization outcome. METHOD: retrospective study of the In Vitro Fertilization Program of the University Hospital, Faculty of Medicine of Ribeirão Preto, University of São Paulo. A total of 137 patients submitted to the transfer of 439 embryos were evaluated. The main outcomes measured were pregnancy and implantation rates. RESULTS: a significant difference in the three scoring systems was observed between pregnant (n=53) and non-pregnant (n=84) patients (p<0.0001). In the first embryo scoring system, in which cell number alone was used, higher pregnancy (70%) and implantation rates (42%) were observed when embryos with a mean blastomere number higher than 8 were transferred. Scoring system 2, based on a total four-point score (cleavage stage, blastomere number, fragmentation and symmetry), showed increased pregnancy (52.8%) and implantation rates (31%) for scores above 2. Scoring system 3, based on cell number and morphological criteria, also showed higher pregnancy and implantation rates with increasing average scores of the transferred embryos. CONCLUSION: the three scoring systems assessed in 3-day embryos were positively correlated with pregnancy and implantation rates.