Sperm testing in UK labs fails to meet World Health Organization standards, raising concerns over infertility misdiagnoses, a study suggests.
Differences in sperm analysis affect diagnoses
The paper, published online by Human Reproduction, surveyed 37 labs.
The Bristol and Sheffield-based researchers found only 5% of the clinics met all WHO standards for assessing the size and shape of sperm.
They warn this means clinics could be "over-diagnosing" certain problems resulting in unnecessary treatments.
Sperm morphology - its size and shape - is known to be a significant indicator of male fertility levels, as the sperm has to be a normal shape to pass though the cervical mucus on its way to the womb.
It is one of the areas that laboratories analyse to assess whether a man has fertility problems, and to enable doctors to decide if the couple need treatment to help them conceive.
Couples affected in this way are offered ICSI (Intracytoplasmic Sperm Injection), where a single sperm is injected directly into a woman's egg.
Over the past 15 years, the WHO has issued a series of recommendations on how clinics should measure sperm morphology.
Measurements 'not robust'
Nineteen laboratories specialising in sperm analysis and 18 in district general hospitals responded to the survey carried out by researchers from the Universities of Bristol and Sheffield.
There are about 95 specialist labs and 200 non-specialist in the UK.
Their work is largely regulated by the Human Fertilisation and Embryology Authority.
Of the labs surveyed, 43% looked at samples which were unstained.
"Staining" fixes sperm in place so they can be analysed more easily, and the WHO recommendations for sperm width and length are based on stained sperm.
Only 16% of clinics looked at the sperm under the recommended microscope magnification.
And only 30% counted enough sperm on the microscope slide to make the measurement a robust one, the researchers said.
The WHO recommends at last 200 sperm have to be examined to make an assessment of morphology.
But the majority of clinics in the survey were looking at 100 or less.
Writing in Human Reproduction, the researchers said: "If an assessment is made on fewer than this number, it is entirely plausible that teratozoospermia [poorly shaped sperm] warranting the use of ICSI may be diagnosed, whereas in reality the sample is completely normal."
Dr Allan Pacey, Senior Lecturer of Andrology at the University of Sheffield and a co-author of the report, said: "This is a difficult measurement to perform in the lab, but for so many to ignore the guidelines in such a way increases the probability of finding problems when there really aren't any."
"It's more likely that people are over-treated, rather than not treated at all.
"Couples could be guided towards more costly treatments such as ICSI whereas less sophisticated treatments might have been just as effective."
Kate Whittington, lecturer in reproduction and development at the University of Bristol, who led the research, said: "It is very disappointing, that more than five years after the publication of the guidelines that our survey should find that only 5% of the UK laboratories that responded were compliant with all of the WHO recommendations."
Matt Tomlinson, chairman of the Association of Biomedical Andrologists which was set up to oversee training and standards for those analysing the causes of male fertility, accepted that many clinics did not adhere to the WHO standards.
He said: "The ABA was set up in response to the need for more training and standardisation in clinics.
"It's foolish of labs to ignore the guidance that is there."
An HFEA spokesman said: "Work is already underway on establishing for the first time a set of ART laboratory standards which draws together guidelines from all professional bodies.
"We have taken account of WHO andrology standards and our inspections continue to reflect this."