CONTROLLED COMPARISON OF EARLES BALANCED SALT SOLUTION WITH MENEZO B-2 MEDIUM FOR HUMAN IN-VITRO FERTILIZATION PERFORMANCE

In order to optimize the in-vitro fertilization (IVF) procedure and to avoid the batch-to-batch fluctuations of in-house culture medium, we investigated the use of a commercially available medium. In our human IVF programme, a controlled comparison was performed from July 1991 to February 1992 between in-house Earle's medium and commercially availa ble Menezo B-2 medium. The major difference between the two tested med ia is the additional presence of amino acids and water-soluble vitamin s in Menezo B-2 and the different origins of the protein source, i.e. bovine serum albumin (BSA) in Menezo B-2 and human serum albumin (HSA) in Earle's medium. In the first, autocontrolled study, sibling oocyte s cultured in Menezo B-2 showed a significantly higher fertilization r ate than those cultured in Earle's medium: 58.1 +/- 37.2% and 52.1 +/- 36.9% respectively. After further culture of the fertilized oocytes, there was no difference in the morphological characteristics of the em bryos cultured in the different media, although the rate of developmen t was different. In Menezo B-2 medium, a higher proportion of the embr yos had reached at least the 4-cell stage at transfer. In the second, randomized study, effects on the pregnancy and implantation rates of b oth media were analysed. In the group of oocytes cultured in B-2, more excellent or good-quality embryos were available for transfer at a mo re advanced stage of development. No significant difference in pregnan cy rate was observed: 39.1% per transfer in Earle's medium versus 40.5 % per transfer in Menezo B-2. The implantation rate per embryo as well as the ongoing implantation rate per embryo did not differ between th e two media: 21.0 and 15.0% respectively for Earle's medium and 20.5 a nd 14.3% respectively for Menezo B-2 medium.