Randomized comparison of three media used for embryo culture after intracytoplasmic sperm injection

Since the metabolic requirements of fertilization and early embryonic devel opment are very different, we have tested a new culture medium (EllioStep2, Ellios Bio-Media, Paris, France) specially designed for the first cleavage s and compared it with two conventional media: BM1 (EIlios Bio-Media, Paris , France) and IVF50 (Scandinavian IVF Science, Gothenburg, Sweden), In orde r to avoid any interference with fertilization, the test was performed as p art of an intracytoplasmic sperm injection (ICSI) study, A. total of 416 IC SI attempts were randomly performed using one or other of the media. After sperm injection, oocytes were incubated either in EllioStep2 or in BM1 or i n IVF50. The embryo quality, pregnancy and implantation rates, number of fr ozen embryos were compared in the different media. The percentage of fair e mbryos (grades 4 and 3) was significantly higher when EllioStep2 was used t han when oocytes was cultured in BM1 medium (54 versus 47%; P < 0.01) or in IVF50 (69 versus 61%; P < 0.01), The pregnancy rate per transfer and the i mplantation rate were not significantly higher with EllioStep2 than with BM 1 or IVF50, However, the percentage of embryo freezings per attempt was sig nificantly higher with EllioStep2 than with BM1 (47/105 versus 28/105; P < 0.01). In conclusion, the use of EllioStep2 is associated with an increase in embryo quality permitting a higher number of embryo freezings.