Human oocyte cryopreservation as an adjunct to IVF-embryo transfer cycles.

BACKGROUND

The purpose of this work was to develop methods for successful cryopreservation of human oocytes.

METHODS

Two cryopreservation procedures were used. Method 1 involved use of 1.5 mol/l propanediol (PrOH)-0.1 mol/l sucrose with medium containing sodium (Na) as cryoprotectant medium, seeding at -7 degrees C, and stepwise dilution of cryoprotectant post-thaw. Method 2 used Na-depleted media with 1.5 mol/l PrOH-0.2 mol/l sucrose for freezing, seeding at -6 degrees C, and use of high sucrose (0.5 and 0.2 mol/l) for cryoprotectant removal.

RESULTS

The first method was used in seven patients, and gave poor (12.3%) survival results and no pregnancies. The second method was used in 15 patients (16 cycles), and yielded good survival and fertilization rates (74.4 and 59% respectively), with four pregnancies and five healthy infants born to 11 women receiving an embryo transfer.

CONCLUSIONS

Using Na-depleted media along with other alterations in freezing and thawing procedures, human oocyte cryopreservation can provide excellent survival and pregnancy rates.