Development of blastocyst-stage embryos after round spermatid injection inpatients with complete spermiogenesis failure

Purpose: Our purpose was to evaluate the progression of embryos derived fro m round spermatid injection to the blastocyst stage and compare the results with those obtained by the use of testicular or epididymal spermatozoa. Methods: Thirty-eight patients with azoospermia enrolled in this study. In 29 patients with obstructive or nonobstructive azoospermia, spermatozoa wer e recovered from epididymis or testis. In the remaining nine cases with non obstructive azoospermia, only round spermatids were found in seven, whereas in two of the patients, there were no elongated or round spermatids. Six o f these cases underwent round spermatid injection. Results: Twenty-one of 29 patients with injection of spermatozoa underwent embryo transfer on day 3, and 10-pregnancies (47.6%) were obtained. In eigh t cycles, embryos were further cultured for delayed transfer. In six cases undergoing round spermatid injection, no transfer was performed on day 3 an d extended culture with delayed embryo transfer was applied. The mean numbe r of fertilized oocytes and mean number of embryos on day 3 and also the fe rtilization rate and mean number of good-quality embryos on day 3, mainly g rade 1 or 2, were statistically significantly higher in the spermatozoa gro up than the round spermatid injection group. Compared to the spermatozoa gr oup, the number of arrested embryos was significantly higher and the number of blastocyst-stage embryos and number of good-quality blastocysts were si gnificantly lower in the spermatid injection group. No blastocysts develope d in two spermatid cycles and embryo transfer was not possible, and in the remaining four cycles, after at least one blastocyst transfer, no pregnanci es were achieved. However, in eight cycles with extended culture in the spe rmatozoa group, embryo transfers were achieved in all and three pregnancies , for a pregnancy rate of 37.5%, were obtained after blastocyst transfer. Conclusions: Our preliminary results showed that round spermatid injection was associated with a significantly lower fertilization and embryo developm ent rate and a significantly higher developmental arrest rate compared with the injection of spermatozoa. Extended culture and delayed embryo transfer did not improve the clinical outcome after round spermatid injection, and these results suggested a. developmental failure in embryos preventing succ essful implantation after round spermatid injection.