An uncomfortable operation to correct a problem supposedly interfering with male fertility actually has no benefit at all, say researchers.
Varicocele was thought to worsen sperm quality
A varicocele is a tangled mass of blood vessels in the testicle caused by blood flow problems.
For years, some doctors have believed that the condition may reduce male fertility - perhaps by causing the testicle to overheat.
Sub-fertile men who have the condition have been offered operations to correct it.
But researchers from the Netherlands have reviewed all the available research about the operation - and concluded it appears to achieve no increase in fertility.
Many perfectly fertile men have varicoceles, they point out.
The rise of new fertility techniques for sub-fertile men since the 1970s offer a viable alternative, say experts.
Varicoceles are caused when blood does not flow properly through the vein leading from the testicle.
One way valves in the vein should prevent blood flowing back down into smaller blood vessels surrounding the testicle, but when they malfunction, the small vessels are enlarged - in a similar manner to varicose veins.
There are two operations to correct this situation - a full surgical approach, in which the skin of the scrotum is cut open and the malformed blood vessels tied off by hand, or a less invasive treatment which uses heat to seal them.
Patients undergoing the first of these can experience significant discomfort and may take weeks to recover.
The Dutch researchers looked at how successful treated men were at subsequently fathering children compared with non-treated men.
In 281 couples in which the man had received an operation, there were 61 pregnancies.
However, there were 50 pregnancies in a smaller number of non-treated men.
The conclusion - that varicocele correction was ineffective.
Professor Allan Templeton, from the University of Aberdeen, agreed that the operation did not seem to be the best option for subfertile men.
"At best, varicocele treatment is marginally effective in a selected group of men," he said.
"At worst, it does more harm than good."
"Further primary research in the field seems unlikely and is now complicated by the availability of an effective alternative treatment - intracytoplasmic sperm injection."