Embryo quality in thawed cycles from frozen pronucleated preembryos: a comparison of growth culture media.

Abstract

Objective: Glucose and phosphate have a detrimental effect on the first stages of embryo development, as it has been demonstrated in some species. Media lacking these two components are intended to enhance human embryo development and pregnancy rates. The purpose of the present study is to compare the reproductive performance of frozen-thawed pronucleated preembryos cultured in media with or without glucose and phosphate. Design: Retrospective and comparative study. Materials/Methods: Between September 1995 and November 2000, 263 frozen pronucleated preembryos from IVF or ICSI cycles were thawed. Human Tubal Fluid (HTF, Irvine Scientific, USA) was used as culture media containing glucose and phosphate in 157 of these cycles, while P-1 medium (Irvine Scientific, USA, without glucose and phosphate) was used in 106 cycles, both supplemented with human serum albumin (hSA) 0.5%. Preembryos remained in culture from thawing to day 3, when they were transferred. Patients from both groups, HTF and P-1, were comparable regarding infertility causes, female age, number of retrieved oocytes, proportion of viable pronucleated preembryos thawed (92.8% vs 89.9%), cleavage rate (96.2% vs 96.8%) and mean number of transferred embryos (3.6 + 1.2 vs 3.5 + 1.0). Main outcome measures were embryo quality and pregnancy and implantation rates. Statistical analysis was performed using t-test or chi square as appropriate. Results: The percentage of cycles having only good quality embryos for transfer was similar in both groups (26.9% vs 21.9%). There were significant differences regarding the overall percentage of good quality embryos in favor of the HTF group (62.9% vs 52.3%, p = 0.002). No differences were found in the pregnancy rate per ET (26.9% vs 25.7%), implantation rate per ET (10.8% vs 9.6%) or ongoing pregnancy rate per ET (22.4% vs 17.1%). Conclusions: Even though the potential detrimental effect of glucose and phosphate on the first stages of embryo development has been reported, cycles in which HTF was used as growth culture medium for thawed pronuclear preembryos showed a higher incidence of good quality embryos. This difference had no impact in achieving more pregnancies or higher implantation rate when compared with P-1 medium. The use of a free glucose and phosphate medium in this series did not give extra benefits in the analyzed parameters.