Etienne Van den Abbeel

CRYOPRESERVATION OF SUPERNUMERARY MULTICELLULAR HUMAN EMBRYOS OBTAINED AFTER INTRACYTOPLASMIC SPERM INJECTION

OBJECTIVE To investigate the pregnancy rate of frozen-thawed human supernumerary multicellular embryos that were cryopreserved after intracytoplasmic sperm injection or IVF. DESIGN A clinical study. SETTING Consenting patients in an academic research environment. PATIENTS Couples with severe male infertility, indicated by failed or sporadic fertilization after IVF or subzonal insemination or by < 500,000 progressively motile spermatozoa in the entire ejaculate, and couples for IVF during the same period. INTERVENTIONS After microinjection or IVF, the three best-quality embryos were transferred, and 1,171 embryos from intracytoplasmic sperm injection compared with 2,495 embryos from IVF were frozen with dimethyl sulphoxide. Of these, 413 and 969 embryos were thawed, respectively. MAIN OUTCOME MEASURE The survival rate, the total and clinical pregnancy rates, the delivery rate, and the preclinical abortion rate were calculated. RESULTS Fifty-three percent of the thawed intracytoplasmic sperm injection embryos survived. Twenty-two pregnancies have been established in 101 transfers, corresponding to a total pregnancy rate of 21.8% per transfer. The clinical pregnancy rate was 12.9% per transfer and the delivery rate was 5.9% per transfer. Of the IVF embryos, 51% survived and 37 pregnancies have been established in 253 transfers. The total and clinical pregnancy rates and the delivery rate were 14.6%, 10.7%, and 7.1%, respectively. The preclinical abortion rate was 40.9% for cryopreserved intracytoplasmic sperm injection embryos and 27.0% for IVF embryos. CONCLUSIONS The high incidence of preclinical abortions after transfer of human embryos cryopreserved after intracytoplasmic sperm injection requires extension of the series.

Clinical validation of a closed vitrification system in an oocyte-donation programme

Controversy exists about the risk of microbiological contamination from direct contact with unsterile liquid nitrogen during oocyte vitrification. The aim of this observational study was to evaluate the effectiveness of oocyte vitrification using a high-security closed vitrification system in a donation programme. Oocyte vitrification was performed using CBS High Security closed straws (Cryo Bio System) with DMSO/ethylene glycol/sucrose as the cryoprotectant (Irvine Scientific freeze kit). A total of 123 vitrified metaphase-II oocytes were warmed in 20 recipient cycles (6.2 warmed oocytes per recipient); of these, 111 oocytes (90.2%) survived vitrification and warming. All surviving oocytes were microinjected and 86 (77.5%) were normally fertilized, of which 53 (61.6%) developed up to good-quality day 3. Ten embryo transfers resulted in a clinical pregnancy (50.0%) and an ongoing clinical pregnancy rate of 45%. Five revitrified embryos were warmed in three warming cycles (survival rate 100%). These transfers resulted in an additional ongoing twin pregnancy, leading to a cumulative ongoing pregnancy rate per patient of 50% (10/20). The ongoing implantation rate per warmed oocyte and per injected oocyte was 10.6% (13/123) and 11.7% (13/111). The present data demonstrate that oocyte vitrification using a closed vitrification device yields excellent oocyte survival, fertilization and embryo development.

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.

Survey on Cryopreservation

In this survey on cryopreservation of human embryos and oocytes, the results from 24 groups that reported replacements of cryopreserved embryos by the end of 1986 were summarized. So far 163 pregnancies have been reported, 65 children have been born, and 61 pregnancies were ongoing at the time of tabulation. The real impact of freezing and thawing of human embryos and oocytes in the treatment of infertility will require a careful analysis of all factors influencing the cryopreservation.

World Results of Human Embryo Cryopreservation

A survey on the practice of human embryo cryopreservation in the world was made up to December 31, 1988.

Should a single blastocyst transfer policy be a clinical decision or should it depend on the embryological evaluation on day 3

BackgroundSingle blastocyst transfer has the advantage of maximizing the fresh single pregnancy rate. However, in patients with a low number of good quality embryos on day 3, it remains unclear whether immediate embryo transfer or further embryo culture with blastocyst transfer is the most preferable option.MethodsA retrospective cohort study was carried out in which the outcome of 590 fresh in vitro fertilization (IVF) cycles over a 15 months period and their cryo cycles were analyzed. A total of 341 patients cycles had an elective day 5 strategy independent of intermediate embryo evaluation while another 249 patients underwent a day 5 embryo transfer only if at least four embryos were available on day 3. Blastocyst vitrification was performed using a closed high security system.ResultsDemographics, stimulation parameters and embryological data were comparable in the two groups. Patients in the elective day 5 group had a lower fresh transfer rate (90.62% vs. 95.18%, p < 0.05) as compared to patients with a day 3 or day 5 embryo transfer policy. No difference was observed in the fresh live birth rate and multiple pregnancy rate per initiated cycle (32.84% vs. 28.92%; 1.17% vs 0%) The projected cumulative ongoing pregnancy rate compensating for double counting in case subjects have more than one pregnancy is not different (42.58% vs. 39.84%).ConclusionsDespite lower fresh transfer rates, elective single blastocyst transfer yields a similar projected cumulative ongoing pregnancy rate as in a policy with cleavage stage or blastocyst transfer depending on a good quality embryo count on day 3.