Prospective randomized study on the cryopreservation of human embryos with dimethylsulfoxide or 1,2-propanediol protocols.

OBJECTIVE

To investigate the optimal protocol for cryopreservation of human embryos obtained from IVF.

DESIGN

Prospective randomized study.

SETTING

Consenting patients in an academic research environment.

PATIENTS

Couples undergoing IVF.

INTERVENTIONS

A cohort of 2,220 supernumerary multicellular embryos were obtained from 488 patients who were randomized over slow freezing protocols with dimethylsulfoxide (DMSO, 819 embryos), 1,2-propanediol (699 embryos) or a mixture of DMSO and 1,2-propanediol (702 embryos). A total of 725 embryos have been thawed (DMSO, 232 embryos; 1,2-propanediol, 250 embryos and DMSO and 1,2-propanediol, 243 embryos) for transfer in natural ovarian cycles.

MAIN OUTCOME MEASURES

Embryo survival rate, embryo implantation rate, clinical pregnancy rate (PR), delivery rate, live-birth rate.

RESULTS

The embryo survival rate was significantly higher with the DMSO protocol (52.6%) than with the 1,2-propanediol (32.0%) or the DMSO and 1,2-propanediol protocols (34.9%). The clinical PR per thawing cycle was significantly higher in the DMSO protocol (17.2%) than in the 1,2-propanediol protocol (3.9%). The clinical implantation rate per embryo thawed was significantly different between a DMSO-frozen embryo (4.7%) and a 1,2-propanediol-frozen embryo (1.2%). A DMSO and 1,2-propanediol-frozen embryo had a 3.7% chance of of implantation. The delivery rate per thawing cycle was significantly higher in the DMSO protocol (12.5%) than in the 1,2-propanediol protocol (2.6%). The live-birth rates per embryo thawed were 3.5%, 0.8%, and 2.9% in the DMSO, 1,2-propanediol, and DMSO and 1,2-propanediol groups, respectively.

CONCLUSION

Supernumerary multicellular embryos as presented in daily clinical IVF practice have the highest chance of survival and of implantation after cryopreservation when DMSO has been used.