Frozen storage of Ham's F10 medium for human in-vitro fertilization.

A method of frozen storage of Ham's F10 medium was investigated that provides 'ready-to-use' culture medium for human in-vitro fertilization, without the necessity of readjusting and testing the medium after thawing. Ham's F10 medium, without bicarbonate, was adjusted to 245 mOsm/kg and stored in aliquots of 33 ml at -20 degrees C. Aliquots of 1 ml of a 7.5% (w/v) sodium bicarbonate solution were stored separately at the same temperature. The two components were mixed together after thawing. In the first test series, mouse embryos were cultured in media stored frozen for varying intervals between 2 weeks and 6 months and no difference in the rates of blastocyst formation was detected. Frozen-stored Ham's F10 medium was then used for human IVF in 256 cycles performed within a 16-month period in two different IVF centres. The pregnancy rates were evaluated and correlated with the duration of the frozen storage (between 1 week and 3 months) and compared to the outcome of 24 cases in which non-frozen medium was used. There was no significant difference in the pregnancy rates in the different groups (19% with non-frozen medium and between 21 and 33% with frozen-stored medium). Thus it was shown that there is no loss of quality of the frozen-stored media within the tested period of 3 months. The prolonged storage interval offers the possibility of extended quality tests and cross-tests between different IVF laboratories.