Is triple gas culture effective? Practical?

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OBJECTIVE: To evaluate and establish low oxygen tension culture (LO2) working parameters for routine implementation in an IVF clinic. DESIGN: This retrospective study included patients undergoing IVF between January 2007 and February 2008. Patients were chosen based on adequate follicular growth to ensure sibling oocyte comparison. Patient oocytes were split evenly after retrieval into low (LO2) or high (HO2) oxygen tension. All oocytes were ICSI'ed, maintained separately and cultured individually. Fertilization rate, cleavage rate, Day 3 8-cell formation, blast cryo rate, ongoing pregnancy rate/transfer and implantation rates were compared between the 2 groups using Chi Square analysis. The best embryos were chosen for transfer regardless of culture method. Only cycles that included transfer of homogeneous embryos with respect to culture group were included in the analysis. MATERIALS AND METHODS: Oocytes and embryos were cultured in Sage sequential media (Cooper Surgical) in either a HO2 or a LO2 environment. All oocytes were ICSI'ed after retrieval and all embryos were assisted hatched prior to transfer. Spare embryos developing to the blast stage were vitrified.Tabled 1HO2LO2# Oocytes2582612pn Fert Rate197 (76.4%)204 (78.2%)Cleavage Rate192 (97.5%)198 (97.1%)8 cell % on D3 (% of 2pns)67 (34.0%)105 (51.5%)1p<0.01.Blast Cryo Rate (% of 2pns)85 (43.1%)89 (43.6%)1 p<0.01. Open table in a new tab Tabled 1HO2LO2Total# of Transfers61824Ongoing Preg / Rate67% (4/6)50% (9/18)54%Implantation Rate50% (4/8)45% (9/20)46%All Comparisons NS. Open table in a new tab All Comparisons NS. RESULTS: In the 24 cycles analyzed, mean age, mean oocytes retrieved and mean embryos transferred were 32.9, 26.5 and 1.2 respectively. Ongoing pregnancy rate/transfer and implantation rate were 54% and 46% for all patients. Percentage of 8 cell formation on day 3 was seen to be significantly higher in the LO2 group. No other comparisons were significant. CONCLUSIONS: LO2 culture conferred some benefit in terms of increased formation of Day 3 8-cell embryos. However, any advantage of this finding was negated by the observation of similar blast formation rates between the 2 groups. The predisposition to select LO2 embryos for transfer may suggest that the quality of embryos developed in LO2 culture was higher than HO2. We did not find any differences between the two groups in our system that would warrant the wholesale exchange of HO2 incubators with LO2 systems. Notwithstanding any subtle molecular enhancements from LO2 tension, LO2 and HO2 culture performed equally in a good prognosis patient population.