Sperm retrieval from men with non-obstructive and obstructive azoospermia is now possible with excellent pregnancy rates for obstructive azoospermia and acceptable pregnancy rates for NOA when ICSI is applied. The ability to use cryopreserved epididymal and often testicular spermatozoa will continue to limit the number of sperm retrieval procedures necessary to achieve fertility for a couple. These advancements, both in sperm retrieval and assisted reproduction, provide the potential of fertility treatment where the only management options were donor insemination or adoption only several years ago. Specific genetic abnormalities are associated with azoospermia in men and careful evaluation of the cause of azoospermia is indicated for all men. Multiple TESE procedures may cause both transient and occasional permanent alterations in testicular function including testicular atrophy and decrease testosterone levels. Therefore, sperm retrieval should preferably be performed by physicians experienced in testicular anatomy and physiology and using an operating microscope.
The location of optimal sperm quality in obstructed is in the proximal portions of the epididymis, vas efferentia, and rete testis, whereas the distal obstructed reproductive tract is the site of sperm degeneration. Spermatozoa retrieved from the testis have been successful in achieving fertilizations and pregnancies for couples in whom epididymal aspiration failed, however reported fertilization and pregnancy rates have been lower than those achieved with epididymal spermatozoa. Of the sperm retrieval and assisted reproductive techniques, the most successful combination reported to date is microsurgical epididymal aspiration with intracytoplasmic sperm injection with fertilization rates and pregnancy rates as high as 45 and 52 percent, respectively.
The greatest published experience to-date with retrieved spermatozoa and ICSI involves patients who had sperm retrieved by MESA. The concentration and motility of epididymal sperm retrieved by MESA is reliably better than that retrieved from the same patients with TFNA or percutaneous testicular biopsy. In our experience with over 150 MESA procedures at Cornell, sperm retrieval from the epididymis with MESA is possible in over 99% of cases. In conclusion, MESA is the optimal choice for retrieval of sperm and subsequent cryopreservation for men with obstructive azoospermia. However, percutaneous testicular retrieval does not require microsurgical expertise and is less invasive.
Further data will allow definition of how to more effectively extract sperm from men with non-obstructive azoospermia, and in vitro manipulation of retrieved sperm from men with obstructed systems may allow optimized results. The role of incompletely developed spermatozoa (i.e., spermatids) for treatment of men with NOA will also be clarified over time. Anecdotal pregnancies and deliveries for men with NOA have been reported using spermatids injected into the female partner's oocytes after extraction of those spermatids from the ejaculate or testis. However, spermatids usually cannot be extracted from the testis if TESE does not yield fully developed spermatozoa. However, these areas of treatment are new, and spermatogonial transplants as well as the use of spermatids for fertilization have been reported in animal models. Since many men with NOA may have significant genetic abnormalities, caution must be exercised before widespread application of these fertility treatments can be accepted as standard therapy.
Whether percutaneous and open sperm retrieval will have equal pregnancy results has yet to be determined. MESA procedures have a more reliable record of sperm retrieval and acquisition of sperm for cryopreservation. Slightly lower, but adequate sperm retrieval and good pregnancy results are achieved with percutaneous techniques with less morbidity. Most importantly, centers should not limit couples' options for treatment based on their own technical limitations, but always provide the option of ICSI with sperm retrieval and the opportunity for microsurgical retrieval to limit the number of sperm retrieval procedures a man must endure.
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