New screening technique may boost IVF success rates
15 November 2010
By Kyrillos Georgiadis
Appeared in BioNews 584
UK-based researchers have developed a new screening technique which could double or triple IVF success rates. The new test allows for any chromosomal abnormalities to be detected in embryos before they are implanted into the mother.
The new technique allows viability of embryos to be tested without risking damage. Dr Simon Fishel, director of CARE fertility clinic in Nottingham, spoke of how the new test is a significant improvement on current methods saying it will make a 'stupendous difference'. Current PGD (preimplantation genetic diagnosis) techniques involve comparative genomic hybridization arrays, the accuracy of which has been questioned, and in utero (in the womb) prenatal screening, which can carry a risk of miscarriage.
'Before we would look down a microscope and see five, six, maybe 10 embryos knowing that half are chromosomally abnormal but there's no way of testing it. We now we have an objective test that is related to the health of the pregnancy', Dr Fishel told the BBC. At around day five of embryo development, the blastocyst has two distinct parts - a group of cells called the embryoblast which will later develop into the body of the fetus, and a group of surrounding cells, the blastocoele, which fuses with the inner membrane of the uterus to form the placenta.
'At this stage we can do a tiny biopsy of those placental cells. So we don't even touch the cells that are going to become the baby itself', Dr Fishel explained. Subsequent chromosomal analysis would show any abnormalities before the embryo is implanted.Chromosomal abnormalities are the largest cause of miscarriages, accounting for over 50 percent of embryos that abort spontaneously in the first trimester, both in IVF and natural conception.
One in 200 newborns has multiple congenital abnormalities because of a chromosomal abnormality. Trials of the new technique, held by fertility specialists at CARE Fertility in Manchester, include three women in their late 30s who having undergone the new procedure will give birth in late December.