Normal-looking sperm may have serious damage; scientists urge more care in...( This release is available in A HREF h...)

Barcelona, Spain: Intracytoplasmic sperm injection (ICSI), where a single sperm is injected into an egg to fertilise it, is increasingly used to help infertile men father children. Although the sperm chosen for the procedure may appear quite normal, researchers in the US have found that many of them in fact have DNA damage, which can decrease the chances of pregnancy.

Mr. Conrado Avendao, from the Jones Institute for Reproductive Medicine, Norfolk, Virginia, USA, and colleagues studied a group of infertile men with moderate and severe teratozoospermia, where most of the sperm looks abnormal. He told the 24th annual conference of the European Society of Human Reproduction and Embryology today (Tuesday 8 July) that, in this group of men, the embryologist would normally select the 'best looking' sperm for injection. "This would typically be done by analysing the sperm's shape under a microscope," he said. "A 'good' sperm by this criterion would have a regular oval head and a long straight tail. However, our research has shown that appearances can be deceptive."

Mr. Avendao and colleagues studied sperm from ten infertile men and found that, despite appearing to be completely normal, many of them had DNA damage (DNA fragmentation). "In routine ICSI procedure, the embryologist chooses the best-looking sperm under the microscope, but it could be damaged," he said. "DNA-damaged sperm has a highly deleterious effect on the ability to achieve a pregnancy. Even if damaged sperm are used and the woman becomes pregnant, the chances of miscarrying are significantly higher."

The researchers compared levels of DNA fragmentation in sperm from the infertile group with that from fertile men. The study was performed by a simultaneous examination of normal sperm morphology using face contrast and DNA fragmentati
'/>"/>