Environmental factors and manual manipulations during preparation influence embryo culture media osmolality

Abstract

OBJECTIVE: Examine the impact of IVF lab conditions used during microdrop preparation on resulting media osmolality. DESIGN: Experimental Study. MATERIALS AND METHODS: Microdrops of P1 media + 10% SSS (10μl, 20μl, and 40μl) were prepared under a variety of laboratory conditions. Drops were pipetted directly onto a dish and covered by oil (Standard), or placed in the dish, covered with oil, removed, and replaced with fresh media (Wash-Drop). Drops were made at room temp or on a 37°C stage, and were prepared in a hood with or without airflow. This resulted in 24 experimental groups. Media osmolality was assessed at 5min and 24h. Each measurement and experiment was performed 3 times. Osmolalities were standardized by subtracting a baseline mean value of control media, as determined by averaging 3 measurements. Bivariate analysis using student's t-tests and ANOVA, as well as multivariate regression analysis, were used to assess treatment effects. RESULTS: Bivariate analysis suggested that reduced drop volume, increased temp and standard prep method were all associated with a significant increase in media osmolality at both 5mins and 24h. Hood airflow alone had no significant impact compared to no-airflow. Multivariate analysis indicated that 10 and 20μl microdrop, 37°C temperature, and standard prep method were associated with a 7.10 (p<0.0001), 2.72 (p=0.04), 5.99 (p<0.0001), and 5.86 (p<0.0001) mOsm increase in media osmolality, compared to 40μl, room temperature, and Wash-Drop method, respectively. In addition, there was a significant interaction effect between hood airflow, decreased drop volume, increased temp and standard prep method (p<0.0001) that can cause an ∼40 mOsm increase in osmolality compared to controls. There was no significant change in media osmolality over time. CONCLUSION: Method of microdrop preparation and environmental conditions in which IVF case set-up is performed results in media osmolality shifts that can impact subsequent embryo development.