Spermatid injection into human oocytes. II. Clinical application in the treatment of infertility due to non-obstructive azoospermia.

We have reported recently the first birth after intrauterine transfer of embryos obtained by injection of round spermatids into oocytes in cases of unexpected azoospermia. Here we provide a complete documentation of the series of 11 cases in which this novel method of infertility treatment was employed. In four of these cases, elongated spermatids were identified in the ejaculate, and it was decided to perform elongated spermatid injection (ELSI). In the other six cases, only round spermatids were present, and round spermatid injection (ROSI) was done. In one case, ROSI was given preference to ELSI because of a very poor viability status of elongated spermatids present in the ejaculate. Fertilization of at least one oocyte was achieved in 10 of the 11 treatment cycles; the fertilization rate in these 10 cycles ranged between 7 and 100% with a mean value of 45%. All of the two-pronucleated zygotes cleaved and were transferred to the patient's uterus. A singleton pregnancy was achieved in two ROSI cycles. Both pregnancies developed uneventfully and resulted in the birth of normal infants. These data show the intra-ooplasmic injection of spermatids obtained from the ejaculate may become the treatment of first choice in patients with non-obstructive azoospermia.