Objective: To describe the preparation of fresh or frozen-thawed epididymal and testicular sperm for intracytoplasmic single sperm injection and to compare the fertilization, embryo quality, and pregnancy rates (PRs) obtained after using these spermatozoa to the results when freshly ejaculated sperm was used for microinjection.
Design: Retrospective analysis of 1,034 consecutive microinjection cycles. Ejaculated (965 cycles), fresh epididymal (43 cycles), frozen-thawed epididymal (9 cycles), and testicular sperm (17 cycles) was used for intracytoplasmic sperm injection.
Setting: Procedures were performed in a tertiary IVF center coupled with an institutional research environment.
Main outcome measures: Semen density and motility were judged by the World Health Organization criteria and sperm morphology was evaluated by the Tygerberg's strict criteria. After microinjection, oocyte intactness, fertilization, embryo cleavage, transfer, and PRs were evaluated and compared.
Results: The median values of total sperm count, total motility and normal morphology were 17.85 x 10(6), 37%, 8% for freshly ejaculated sperm; 46.20 x 10(6), 12%, 9% for fresh epididymal sperm; 0.15 x 10(6), 0%, 0% for frozen-thawed epididymal sperm; and 0.54 x 10(6), 0% for testicular sperm (morphology was not determined). The percentage of intact oocytes after microinjection ranged from 84% to 90%. Normal fertilization rates were high when fresh or frozen-thawed epididymal and testicular spermatozoa were used for the injection (56%, 56%, 48%, respectively) but were significantly lower than for ejaculated sperm (70%). There was a higher proportion of transferable embryos obtained after ejaculated sperm injection than after testicular sperm injection. Forty percent, 58%, 33%, and 46% of cycles had positive serum hCG using ejaculated, fresh, or frozen-thawed epididymal and testicular sperm. Initial pregnancy loss occurred in 26.3% of the conception cycles.
Conclusion: Intracytoplasmic sperm injection can provide high normal fertilization, cleavage, and PRs when fresh or frozen-thawed epididymal and testicular spermatozoa are used, but normal fertilization rates are significantly lower than after microinjection with ejaculated sperm.