Wednesday, July 9, 2008
Science thinks big for better IVF
A new IVF technique involves selecting sperm with a shape and size that indicate good genetic quality. The best are injected into eggs to fertilise them. Results show improved pregnancy rates.
Infertile men can more than double their chances of fatherhood with a new IVF technique, according to the most comprehensive study of the procedure yet conducted.
The results of a major trial of the approach, which builds upon the technique of injecting sperm directly into an egg, suggest dramatic benefits for the one in 12 couples affected by male factor infertility. A far more powerful microscope is used to identify the sperm most likely to succeed.
The results, from a team in Italy, are encouraging for men with an especially poor fertility prognosis and who have tried and failed to have children by IVF at least twice in the past. Their prospect of becoming fathers using the therapy was double that with standard methods, the study found.
The method, which was first developed in 2004 by a team led by Benjamin Bartoov, of BarIlan University in Israel, is called intra-cytoplasmic morphologically-selected sperm injection (IMSI). It involves examining sperm under a high-magnification microscope, about five times more powerful than standard laboratory equipment, to select those with a shape and size that indicates good genetic quality. The best-looking sperm are then injected into eggs.
British scientists hailed the results as the strongest demonstration yet of the new therapy’s benefits. “I don’t think a lot of people in the UK have woken up to this yet, but they are going to have to,” said Allan Pacey, Lecturer in Andrology at the University of Sheffield. “This is strong evidence from a well-designed study. If it can be repeated in two or three studies, people would seriously have to think about changing their approach.”
The treatment builds on the success of intra-cytoplasmic sperm injection (ICSI), a therapy for male infertility that has enabled thousands to become fathers since it was developed in the early Nineties. ICSI involves fertilising an egg in a laboratory by injecting it with a single sperm. As the sperm does not have to swim up to the egg and penetrate it, the method can help men whose sperm would otherwise be too weak. Even when men produce no sperm, doctors can sometimes recover them surgically from the testes.
ICSI is now used in about 40 per cent of the 41,000 IVF cycles performed annually in the UK, and accounts for about 4,500 children born each year. This suggests that upwards of 10,000 men a year could be appropriate patients for the new technique.
The Italian team, led by Monica Antinori, of the Raprui clinic in Rome, has conducted the largest randomised controlled trial to compare outcomes for IMSI and ICSI. It involved 446 couples in which the man was infertile and the woman was not known to have any problems.
The results, which are published in the journal Reproductive Biomedicine Online, show that the IMSI method can deliver considerable improvements in pregnancy rate. The overall pregnancy rate for the IMSI group was 39.2 per cent, compared with 26.5 per cent for the ICSI patients.
Among men with the worst prognosis, who had had at least two failed attempts at ICSI before, the improvement was better still. The pregnancy rate for IMSI was 29.8 per cent, compared with 12.9 per cent for standard ICSI. The miscarriage rate also fell considerably.
Dr Antinori said the findings demonstrate that the technique has potential, particularly for men with a history of IVF failure. “By treating this kind of patient with this technique, we offer them an opportunity to solve their fertility problems. As you can see from the results, the group that has had two or more IVF failures can get more than twice the opportunity to have a pregnancy with this new technique.”
She cautioned, however, that IMSI is about twice as expensive as ICSI, which typically costs between £3,000 and £5,000 per cycle in Britain. It also requires special training for embryologists, and the purchase of expensive high-magnification microscopes.
IMSI is not yet offered in the UK, though it is performed by clinics in Italy, Israel, Switzerland and Spain.
Dr Pacey said: “People have been seduced into thinking that, as long as you’ve got a sperm that’s half decent, it’s got as good a chance as any. But it looks like we can do better than that.”
Source: The Times July 7 2008