Taking sperm directly from the testicles rather than using semen may be a new way to help couples conceive through IVF.
The approach has been used for some time in men who are infertile for reasons such as a blockage in the tubes that take sperm to the penis. But some clinics are now starting to use the approach more widely, for couples who are having trouble conceiving through IVF for unexplained reasons, doctors heard at the European Society of Human Reproduction and Embryology conference in Vienna last month.
Surgical sperm retrieval can be done in several ways, ranging from a relatively minor procedure where sperm is drawn out with a needle, to a longer operation to remove tissue from the testicles.
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One reason for its growing use is the idea that in some couples with unexplained infertility, the reason could be that the man鈥檚 sperm are unhealthy or dying, even though they appear normal. Many clinics now offer sperm DNA testing 鈥� more fragmented DNA indicates fewer healthy sperm 鈥� but it鈥檚 still unclear where the cut-off should be.
The damage to the sperm is thought to happen mainly after they have formed, while they are maturing in storage tubes next to the testes. It鈥檚 reactive chemicals called free radicals that cause the damage. They are generated by high temperatures, smoking, obesity and other factors.
Several studies have shown that in infertile men, 鈥� presumably because it has skipped the potentially damaging maturation stage. 鈥淔ree radicals are very detrimental to sperm DNA,鈥� says Sandro Esteves of Androfert in Campinas, Brazil.
Sceptics say it is safer to use sperm from semen, in case taking sperm from the testicles selects one that has chromosome abnormalities and couldn鈥檛 have fertilised the egg naturally.
At the ESHRE conference, Esteves presented results from 86 couples who had unexplained infertility and high DNA fragmentation levels 鈥� 36 of them had IVF using sperm from their testicles while the rest used sperm from semen. Regardless of the method used, their eggs had a similar chance of being fertilised and developing into embryos with the right number of chromosomes.
But Kevin McEleny of Newcastle Fertility Centre, UK, who was not involved in the study, says we need to wait until randomised controlled trials have shown the approach is safe and boosts pregnancy rates before adopting it more widely. 鈥淭here鈥檚 a cost, it鈥檚 an intervention, and it鈥檚 more uncomfortable,鈥� he says. 鈥淯ntil they show us that there鈥檚 an improved live birth rate with healthy children, I鈥檓 not convinced.鈥�
