LONDON, APR. 1, 2001 (Zenit.org).- A test on pregnant women to check for Down syndrome causes up to four healthy babies to be miscarried for every abnormality it detects, a study has shown.
Amniocentesis — a procedure in which a long needle is inserted into the womb to draw off fluid for genetic testing — is typically used when other, less definitive tests have shown there is a risk of Down´s, the Sunday Times reported today.
About 40,000 women a year undergo it. Only about 100 unborn babies are confirmed with the syndrome, but the study found that up to 400 healthy unborn babies are subsequently miscarried.
Amniocentesis usually follows blood screening or ultrasound scans that indicate an unborn child may have Down syndrome. The study examined what happened when amniocentesis tests are carried out after ultrasound scans alone.
It found that some of the features on ultrasound scans which doctors are taught to identify as warning signs of Down syndrome are misleading, or even possibly worthless. It could mean that many women are being urged to have amniocentesis — and run the risk of miscarriage — unnecessarily, the Sunday Times said.
Professor Rebecca Smith-Bindman, of the University of California in San Francisco, who led the Anglo-American research team during a sabbatical year at St. Bartholomew´s medical school, London, said amniocentesis should be used more selectively.
Her findings were welcomed by Kypros Nicolaides, the head of fetal medicine at King´s College hospital, London, who has campaigned against the increased use of invasive testing in pregnancy. «There has been an explosion in invasive testing since the 1970s,» he said. «The incidence of Down syndrome has not increased, but the number of tests has jumped from 3,500 to 40,000 a year, with an all-too-predictable loss of life.»
About 1,000 babies are born with Down´s each year in Britain. It is caused by a chromosomal abnormality and leads to mental retardation.
Older women are at higher risk and one reason for the surge in amniocentesis tests is a trend toward women having babies later in life. Many women also prefer to have amniocentesis, and accept the risk of miscarriage, rather than risk having a baby with Down´s — meaning that they then usually abort those afflicted with the syndrome. The women are told the chance of miscarriage associated with amniocentesis is 1%.
Meanwhile, a top hospital trust has been criticized for apparent discrimination against handicapped babies who needed life-saving heart surgery.
The report of an investigation into the treatment of 49 children at the Royal Brompton and Harefield Trust in west London describes a catalogue of mismanagement and delays, which in some cases was followed by the death of the child. Five families have launched medical negligence claims.
