Fertility clinics should stop recommending a £2,000 embryo quality test because there is no evidence that it works and it could damage patients’ chances of pregnancy, an influential group of medical professionals says.

The British Fertility Society (BFS) is to advise its members not to offer the pre-implantation genetic screening (PGS) test, which is approved for women who are over 35 or who have a history of IVF failure and miscarriage, The Times has learnt.

The procedure is designed to choose embryos with the best chance of developing normally, by screening for genetic abnormalities. Eight British clinics are licensed to perform preimplantation genetic screening. It costs typically about £2,000, and is not available on the NHS. A review by the British Fertility Society of published research, however, has found no evidence that it improves pregnancy rates and some indications that it might actually harm infertile couples’ chances of having a baby.

The society, which represents 800 doctors, nurses and counsellors involved in reproductive medicine, will say that the test should ideally be offered in a research setting. Its new policy, which has been seen by The Times, will also insist that any patients who want PGS should be warned that there is no evidence that it is helpful.

Richard Anderson, Professor of Clinical Reproductive Science at the University of Edinburgh, who led the review, said that although PGS was still being refined and might one day be useful the existing research was too flimsy to justify selling it to patients.

“There is a conflict between the published evidence from properly defined clinical studies and the opinions of people who consider themselves experts in this,” he said. “This is one of those issues where medicine and money clash, and I do not think they make happy bedfellows.”

The new policy will say: “It is clear that there is currently no compelling evidence that PGS improves the clinical pregnancy rate or live birthrate or reduces the miscarriage rate. It remains possible that PGS may be of benefit under certain circumstances, for example where the number of embryos replaced is strictly limited. Therefore, PGS should preferably be offered within the context of robustly designed randomised trials performed in experienced centres.”

An earlier draft had recommended that PGS be offered only as part of a clinical trial, but Professor Anderson said the BFS had reluctantly agreed to water down this conclusion after comments from the test’s practitioners.The document will say: “Patients should be informed that there is no robust evidence that PGS for advanced maternal age improves live birthrate. Indeed from the evidence available the live birthrate may be significantly reduced following PGS.” It will also call for further research.

Alan Thornhill, scientific director of the Bridge Centre in London, said that PGS could be beneficial for certain patients. His clinic offers it to about 5 per cent of women, who are known to be at high risk of the chromosomal abormalities it detects.

“The key is patient selection,” he said. “It is not helpful across the board, but that is not how it is done and there are clearly patients who can benefit from undertaking PGS. To decree that it should happen in randomised clinical trials is all very well, but there are very specific individual patients who can be helped outside that setting.”

PGS has been licensed in Britain since 2002 for women who have had repeated miscarriages or multiple failed attempts at IVF. In 2005, the last year for which figures are available, 205 cycles were conducted on 166 women, with 42 live births.

It aims to detect a chromosomal disorder called aneuploidy, which affects up to two thirds of embryos and causes them to die or miscarry. However, it has been tested in only two randomised prospective studies, neither of which showed a benefit.

The most recent study, from the University of Amsterdam, found that PGS actually reduced birthrates. Its methodology, however, has been heavily criticised by PGS experts.

How it works

— Pre-implantation genetic screening (PGS) is designed to detect a kind of chromosomal disorder called aneuploidy, which affects up to two thirds of embryos and causes implantation failure or miscarriage

— While healthy cells have 23 pairs of chromosomes, aneuploid embryos have too many or too few copies of one set. PGS screens the eight chromosomes that most frequently malfunction

— It works on the same principle as preimplantation genetic diagnosis for inherited diseases such as cystic fibrosis. A single cell is removed from an embryo of eight cells and tested. Only normal embryos are implanted to the womb

— While clinics that offer it claim improved pregnancy rates among older patients and those with a history of IVF failure or miscarriage, this is not backed up by research

— The most recent clinical trial, led by Sebastiaan Mastenbroek of the University of Amsterdam, found that PGS reduced IVF success rates in women aged 35 to 41 The study, however, has been widely criticised for its methods

— A further issue with PGS is that some embryos are “mosaic”, with some cells that are aneuploid and some that are normal. This can lead to false positive results

Source: British Fertility Society, Times database

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