ABSTRACT
In contrast to OA patients, however, where viable sperm can easily be retrieved from the frozen specimens, the impaired quality of the testicular tissue of NOA patients does not allow cryopreservation and later use of the thawed material for ICSI in all cases. As has been demonstrated for ejaculated sperm, a significant decrease in sperm motility and viability by freezing and thawing also occurs for testicular sperm (LOE II) (10). This implies that cases with extremely low numbers of sperm retrieved can hardly be considered candidates for cryopreservation. Preliminary diagnostic surgery and freezing can, therefore, be considered a controversial approach for them. There is indeed a high chance (≥50%) that sperm will not be found because of complete absence of spermatogenesis or a limited amount of tissue excised and/or the rather limited duration for sperm searching at a diagnostic occasion. In order to overcome the risk that the frozen material is inadequate for injection upon thawing, some in vitro fertilization (IVF) centers define strict limits for testicular sperm quality suitable for freezing, and other centers only allocate patients for treatment on the basis of sufficient quality (motility) of a preliminary thawed testicular specimen. In this way, patient populations with NOA may greatly differ from one IVF clinic to the other and may determine the success of ICSI in NOA patients.
