Sperm taken by biopsy from the testicles of men with a certain kinds of infertility and used in IVF can be cryopreserved without reducing the chances of a successful pregnancy.

This is the conclusion of scientists at an infertility clinic in Washington, USA, after evaluating 15 years' worth of data on testicular biopsies.

Although fertilisation rates were slightly lower for fresh sperm (47 percent versus 62 percent for cryopreserved sperm), there were no significant differences when it came to delivery rates.

'This study demonstrates that using frozen sperm taken by biopsy works as well for most patients in what matters most - pregnancy rates,' said Professor Randall Odem, co-author of the study.

The study included 136 men who had been biopsied between 1995 and 2009 for fertility problems ranging from obstructive azoospermia (having no sperm in the semen, for instance after a vasectomy), to patients who needed sperm extraction due to cancer treatment or other medical reasons. All men underwent a procedure called TESE - testicular sperm extraction - in which a bit of testicular tissue is biopsied to try to retrieve sperm cells that are not present in their semen.

For the majority of men, samples were cryopreserved after biopsy. However, for 21 patients, fresh sperm was used. For this, samples were transported at body temperature to the IVF laboratory less than 30 minutes away. Intracytoplasmic sperm injection (ICSI) - a treatment that injects a sperm cell directly into in egg cell - was used for all patients.

'The convenience and ease of being able to use frozen sperm taken by biopsy in ICSI offers many advantages over fresh sperm', said co-author Dr Kenan Omurtag.

When using fresh sperm, for example, the biopsy for the sperm retrieval would have to be done within hours of the egg retrieval from the woman. These sorts of time constraints evaporate if the sperm can be cryopreserved and banked.

Overall, the study points to the reliability of cryopreservation. However, the fresh sperm group's small size (21 patients), together with the fact that data from only one clinic was used mean the results should be interpreted with caution.

Reproduced from BioNews with permission, a web- and email-based source of news, information and comment on assisted reproduction and human genetics, published by Progress Educational Trust.