CRYOPRESERVATION OF SUPERNUMERARY MULTICELLULAR HUMAN EMBRYOS OBTAINED AFTER INTRACYTOPLASMIC SPERM INJECTION

Objective: To investigate the pregnancy rate of frozen-thawed human su pernumerary multicellular embryos that were cryopreserved after intrac ytoplasmic sperm injection or IVF. Design: A clinical study. Setting: Consenting patients in an academic research environment. Patients: Cou ples with severe male infertility, indicated by failed or sporadic fer tilization after IVF or subzonal insemination or by <500,000 progressi vely motile spermatozoa in the entire ejaculate, and couples for IVF d uring the same period. Interventions: After microinjection or IVF, the three best-quality embryos were transferred, and 1,171 embryos from i ntracytoplasmic sperm injection compared with 2,495 embryos from IVF w ere frozen with dimethyl sulphoxide. Of these, 413 and 969 embryos wer e thawed, respectively. Main Outcome Measure: The survival rate, the t otal and clinical pregnancy rates, the delivery rate, and the preclini cal 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 ra te 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 establi shed in 253 transfers. The total and clinical pregnancy rates and the delivery rate were 14.6%, 10.7%, and 7.1%, respectively. The preclinic al abortion rate was 40.9% for cryopreserved intracytoplasmic sperm in jection embryos and 27.0% for IVF embryos. Conclusions: The high incid ence of preclinical abortions after transfer of human embryos cryopres erved after intracytoplasmic sperm injection requires extension of the series.