Prospective controlled study to evaluate laboratory and clinical outcomes of oocyte vitrification obtained in in vitro fertilization patients aged 30 to 39 years.

OBJECTIVE: To determine whether the process of oocyte vitrification affects oocyte viability in in vitro fertilization (IVF) patients between 30 and 39 years of age. DESIGN: Prospective controlled study. SETTING: Private IVF practice. PATIENT(S): A total of 30 women assigned and 22 qualified. INTERVENTION(S): Denudation of oocytes, cryopreservation of oocytes using vitrification method in a medium with 15% ethylene glycol (EG), 15% dimethylsulfoxide (DMSO), and 0.5 M sucrose. MAIN OUTCOME MEASURE(S): Oocyte survival, fertilization, day-3 embryo quality, blastocyst formation, clinical pregnancy, implantation, and live-birth rates. RESULT(S): After denudation of oocytes, mature sibling oocytes were randomly allocated to the fresh and vitrified groups. The survival rate was 79.6% after vitrification/warming. Overall, no statistically significant differences were found in fertilization, day-3 embryo quality, or blastocyst formation rates between the fresh and vitrified groups. The positive ß-human chorionic gonadotropin, clinical pregnancy rate, and implantation rate were 13 (59.0%) of 22, 10 (45.4%) of 22, and 16 (30.1%) of 53 for the vitrified group. The overall efficiency in achieving a live birth was 11 (5.9%) of 186 per vitrified oocyte. CONCLUSION(S): The impact of vitrification can be reduced to a minimal level, making it possible to achieve high pregnancy and implantation rates in this age group of IVF patients.

Lysed cell removal promotes frozen-thawed embryo development.

OBJECTIVE: To develop a mouse model to investigate the possible causes for increased success rates when lysed cells are removed from thawed embryos. DESIGN: Experimental study. SETTING: Clinical IVF laboratory. INTERVENTION(S): Assisted hatching, cell lysis, and removal of lysed cells. MAIN OUTCOME MEASURE(S): Embryonic growth rate and morphology. RESULT(S): The mouse embryos were divided into three groups; control (no cell lysis), group 1 (cell lysis and removal), and group 2 (cell lysis only). There was no significant difference in the initial number of blastomeres in each group or the number of cells lysed artificially in groups 1 and 2. The rate of embryonic development showed a significant delay in group 2 (7.97 +/- 4.92; control, 10.42 +/- 8.18; group 1, 5.74 +/-4.42; group 2). The embryo morphology on day 4 was significantly improved in group 1 and the control group when compared with group 2. CONCLUSION(S): Mouse embryos with artificially lysed cells after thawing had poorer developmental quality and growth rates compared with control embryos. However, removal of lysed cells restored the embryo's developmental potential to that of the control. Cell number and morphology was also significantly improved compared with embryos without lysed cell removal. These findings are consistent with human embryo development after thawing when lysed cells are present and thus mechanical lysis seems to be an appropriate method by which to further study frozen-thawed lysed cell removal.