Improved High-Quality Blastocyst Formation Rates Result From In Vitro Embryo Culture in the Cook Minc Incubator Platform

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Background: A number of novel sophisticated incubator platforms have emerged in recent years specifically marketed and designed for in vitro fertilization (IVF) and embryo culture. However, clinical data are limited regarding the efficacy of the most recently produced IVF incubator platforms. Manufacturers of some of the more sophisticated incubators claim faster environmental recovery rates, lower gas consumption, and higher temperature stability versus more conventional incubator designs. Objective: The objective of this study was to compare the efficacy of the Cook Minc incubator versus conventional dessicator culture for five- and six-day human in vitro embryo culture. Materials and Methods: A prospective internally controlled study was initiated in a private infertility and IVF clinic, which included 16 patients undergoing IVF. Initiated at oocyte retrieval, each patient's oocyte cohort was split between conventional glass dessicators and Minc incubator for subsequent IVF and embryo culture. Gas mixtures used a triple gas mixture (5% oxygen content) and optimized individual carbon dioxide concentrations that yielded comparable media pH. Embryos were cultured for up to six days. Embryo transfer occurred on either D3 or D5 and, irrespective of the culture platform, the best embryos were chosen for embryo transfer. A paired t test was used to evaluate statistical differences between fertilization, cleavage, day-three eight-cell formation, day-three six-cell formation, day-three good-quality embryo formation, blastocyst formation, and pregnancy rates between the dessicator and Minc groups. Results: Fertilization (72 ± 7% vs. 78 ± 4%), cleavage (98 ± 1% vs. 99 ± 0%), day-three embryo eight-cell formation (56 ± 9% vs. 49 ± 10%), day-three embryo quality, day-five blastocyst formation (58 ± 6% vs. 60 ± 8%), and total blastocyst formation rates (62 ± 7% vs. 64 ± 7%) were statistically similar between the Minc and dessicator culture groups, respectively. However, good-quality blastocyst formation rates, defined as those blastocysts better than 3BB per Gardiner's blastocyst grading criteria, were significantly higher in the Minc culture group versus the dessicator group (42 ± 7% vs. 21 ± 6%; P<.05). The mean number of embryos transfered from each culture group did not differ significantly between the Minc and desiccator groups (1.1 ± 0.1 vs. 1.3 ± 0.2). Overall, there was a clinical pregnancy rate of 75% for all cycles included in the study (12/16). Conclusions: Results of this study suggest the Minc incubator may not provide marked advantages over conventional dessicator culture for the six-day culture of human embryos in the IVF laboratory. The majority of the outcome measures evaluated in this study suggested no differences between the two culture platforms. However, the Minc incubator did produce a significantly higher rate of good-quality blastocysts than did dessicator culture. These data may reflect subtle differences in the stability and consistency of the Minc incubation environment, which may potentiate or manifest via differences in D5 or D6 blastocyst quality.