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Time-lapse spots faulty embryos before IVF

Time-lapse imaging can spot small differences in embryo growth that could have a big impact on the success rate of IVF.
"It's the most exciting breakthrough in 30 years," claims Simon Fishel at CARE Fertility clinic in Nottingham, UK, who developed the new technique.
Together with his colleagues, Fishel has devised a way to record and analyse the development of early embryos collected for IVF. The ability to identify embryos with the best chance of producing a healthy pregnancy is vital for couples undergoing expensive IVF treatment, which can cost up to £10,000 per cycle.
Around half of all human embryos have a chromosomal abnormality. After fertilisation, these embryos normally fail to attach to the wall of the uterus or end in miscarriage. For couples having IVF, chromosomal abnormalities are the largest single reason treatment fails. Until now, the only way to identify chromosomal abnormalities was by an invasive biopsy to remove one or two cells from the outside of the developing embryo, which can risk damaging remaining cells.
Watching them grow To keep a watch over developing embryos, Fishel and his colleagues used an existing video system to film 72 newly fertilised eggs in their incubator until they become blastocysts – the small ball of cells that is then implanted into the womb. This takes about four days. The eggs sit in a closed box with a viewing screen. A seal keeps the new embryos' environment constant. "It's almost like having embryos in the womb with a microscope on them," says Fishel.
The team used the time-lapse footage to study 88 embryos from 69 couples. They found that embryos with chromosomal abnormalities generally take about six hours longer to form a blastocyst.
An embryo follows genetic instructions from the egg for the first three days after fertilisation when its own genes take over. Fishel suggests that the delay in forming a blastocyst could reflect missing or malfunctioning genes in an embryo with a chromosomal abnormality.
The team then devised an algorithm that can identify embryos that grow more slowly than usual. Those that take more than 100 hours to begin forming a blastocyst are considered at high risk of chromosomal abnormality. The algorithm also monitors when a blastocyst becomes fully formed, a secondary indicator of good health.
The time-lapse technology has also revealed new developmental abnormalities. For example, the researchers have seen early embryos grow from two cells to three but then shrink back to two cells before dividing into four. "We see ridiculous changes that we'd never pick up without the time-lapse," says Fishel.
Using previous selection methods, about 50 per cent of implantations at CARE fertility clinics lead to live births. The team estimates that the new technique could raise the success rate to 78 per cent – roughly three times the national average for IVF treatment in the UK.
"Time-lapse imaging of the early development of human embryos offers the exciting potential of a novel and non-invasive way of selecting the embryo with the greatest chance of implantation," says Stuart Lavery, IVF director at Hammersmith Hospital, London. However, he says that to confirm the estimated improvement in IVF outcome, "a prospective randomised trial comparing time lapse imaging with standard embryology selection techniques would be necessary".

Press Article