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 epididymalspermatozoa with intracytoplasmic sperm injection (ICSI) forsevere cases of male infertility are reviewed. A total of 72consecutive microsurgical epididymal sperm aspiration (MESA)cases were performed for congenital absence of the vas (CAV)and for irreparable obstructive azoospermia. ICSI was used toobtain normal embryos for transfer and fertilization in 90%of the cases. The overall fertilization rate was 46% with anormal cleavage rate of 68%. The pregnancy and delivery ratesper transfer were 58 and 37% respectively. The delivery rateper cycle was 33%. In many cases, no epididymal spermatozoawere available and so testicular sperm extraction (TESE) wasused for sperm retrieval. The transfer rate was lower with TESE(84 versus 96%) and the spermatozoa could not be frozen andsaved for use in future cycles. However, there was little differencein pregnancy rates using epidiymal or testicular spermatozoa.The results were not affected by whether the obstruction wascaused by CAV or failed vasoepididymostomy. Both fresh and frozenspermatozoa gave similar results; the only significant factorappeared to be the age of the female. Because of the consistentlygood results obtained using epididymal sperm with ICSI whencompared with conventional IVF, and the similarly good resultswith testicular tissue spermatozoa, ICSI is mandatory for allfuture MESA patients. All CAV patients and their partners shouldbe offered genetic screening for cystic fibrosis; hence pre-implantationembryo diagnosis should be available in any full service MESAprogramme. It is now clear that even with non-obstructive azoospermia,e.g. Sertoli-cell only, or maturation arrest, there are usuallysome small foci of spermatogenesis which allow TESE with ICSIto be carried out. This means that even in men with azoospermiadue to absence of spermatogenesis or to a block in meiosis,there are usually a few spermatozoa available in the testesthat are adequate for successful ICSI. Finally, it is likelythat some forms of severe male factor infertility are geneticallytransmitted and although ICSI offspring have been shown to becompletely normal, it is possible that the sons of these infertilecouples will also require ICSI when they grow up and wish tohave a family.