Another flaw in the triple test for pregnant women seems to have been uncovered – it doesn’t work too well on Asian women. The test is designed to detect Down’s syndrome in the unborn fetus, and comprises ultrasound, serum screening and amniocentesis.
Researchers from the Doncaster Royal Infirmary in England found that Asian women given the test were showing high false-positive readings – that is, indicating Down’s syndrome when it
was not actually there – almost irrespective of their age.
Conversely, two Asian women gave birth to Down’s syndrome babies when they had both had negative readings.
This failure among Asian women is a mystery to researchers at the hospital. The general success rate of the test is based on white women, but in theory there is no reason why it should not apply equally to other races. Ironically, serum screening was introduced in the health district to reduce the false-positive rate (BMJ, January 13, 1996).