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.