16 June 2008
The British Fertility Society (BFS) has published new guidelines on the use of preimplantation genetic screening - PGS (see BBC news). PGS involves testing cells removed from early embryos produced during in vitro fertilisation (IVF) to detect chromosomal abnormalities prior to implantation. Embryos with chromosomal abnormalities can appear normal during the early stages of development; however, following implantation they may not develop properly leading to a reduction in the chances of a successful pregnancy. Currently, the Human Fertilisation and Embryology Authority (HFEA) allows clinics to use this procedure to treat older women, those who have had several unsuccessful IVF attempts and those who have had several miscarriages.
The new guidelines produced by the BSF are published in the journal Human Fertility following a review of published research on the safety and success rates of PGS. The lack of robust evidence in favour of PGS has led the authors to recommend that it should “preferably be offered within the context of well-designed randomised trials performed in suitably experienced centres” (see press release). The guidelines also state that clinicians should inform patients about the lack of evidence and recommend that further research be carried out to assess the safety and efficiency of this procedure. They stress that these guidelines refer to preimplantation genetic screening and not preimplantation genetic diagnosis (PGD), which is a specific test, offered to patients who are at a high risk of transmitting a known genetic disorder to their child.