A new male infertility test could spare women the heartache of unnecessary treatments, American and Japanese scientists said on Wednesday.

The test looks for a protein called ubiquitin that can indicate damage in sperm cells. High levels of the protein in sperm mean there is a male infertility problem.

"Ubiquitin appears to be a universal marker of semen abnormalities, recognising a wide range of sperm defects and also contaminants in semen," said Peter Sutovsky of Oregon Health Sciences University.

The test, called sperm-ubiquitin tag immunoassay (SUTI), detects the protein using antibodies. Initial studies of the new method are reported in the journal Human Reproduction.

"It is very sensitive," Sutovsky, a reproductive biologist, said in a telephone interview.

"I think SUTI could be the first truly objective assay for male infertility, based on an exact, fully automated measurement of a single protein in sperm."

The antibodies could also help scientists find a way to delete damaged sperm from samples used for IVF treatments, which could improve the chances of success.

About 10 percent of couples have an infertility problem and cannot conceive after a year of trying. One third of cases are due to a male problem which is usually sperm-related.

In about one fifth of couples the reason for infertility is unexplained.

Scientists can examine sperm under a microscope to look for abnormalities in its shape, movement and numbers but the results can be inconsistent and all sperm defects aren't evident.

Dr Yukihiro Terada, of Tohoku University in Sendai, Japan, said SUTI could help detect the problem quickly.

"This enables a more accurate diagnosis and could direct the treatment of infertility towards the man, sparing his partner excessive examination and possibly even unnecessary treatments."

When SUTI was used to examine 17 semen samples, it either confirmed a previously diagnosed infertility problem, indicated reasons underlying the problem that had not been evident before or confirmed there was no problem.

In three cases the test showed the men could be contributing to their partner's already recognised infertility.

The researchers are beginning large trials of SUTI in the United States and Japan to confirm their initial findings.

(From ChinaDaily)