Genetics: The use of epididymal and testicular spermatozoa for intracytoplasmic sperm injection: the genetic implications for male infertility

The results and rationale of using testicular and epididymal spermatozoa with intracytoplasmic sperm injection (ICSI) for severe cases of male infertility are reviewed. A total of 72 consecutive microsurgical epididymal sperm aspiration (MESA) cases were performed for congenital absence of the vas (CAV) and for irreparable obstructive azoospermia. ICSI was used to obtain normal embryos for transfer and fertilization in 90% of the cases. The overall fertilization rate was 46% with a normal cleavage rate of 68%. The pregnancy and delivery rates per transfer were 58 and 37% respectively. The delivery rate per cycle was 33%. In many cases, no epididymal spermatozoa were available and so testicular sperm extraction (TESE) was used for sperm retrieval. The transfer rate was lower with TESE (84 versus 96%) and the spermatozoa could not be frozen and saved for use in future cycles. However, there was little difference in pregnancy rates using epidiymal or testicular spermatozoa. The results were not affected by whether the obstruction was caused by CAV or failed vasoepididymostomy. Both fresh and frozen spermatozoa gave similar results; the only significant factor appeared to be the age of the female. Because of the consistently good results obtained using epididymal sperm with ICSI when compared with conventional IVF, and the similarly good results with testicular tissue spermatozoa, ICSI is mandatory for all future MESA patients. All CAV patients and their partners should be offered genetic screening for cystic fibrosis; hence pre-implantation embryo diagnosis should be available in any full service MESA programme. It is now clear that even with non-obstructive azoospermia, e.g. Sertoli-cell only, or maturation arrest, there are usually some small foci of spermatogenesis which allow TESE with ICSI to be carried out. This means that even in men with azoospermia due to absence of spermatogenesis or to a block in meiosis, there are usually a few spermatozoa available in the testes that are adequate for successful ICSI. Finally, it is likely that some forms of severe male factor infertility are genetically transmitted and although ICSI offspring have been shown to be completely normal, it is possible that the sons of these infertile couples will also require ICSI when they grow up and wish to have a family.