[Prenatal ultrasonic diagnosis and Down's syndrome]

A total of 8,923 children were born at the Regional Hospital, Trondheim, Norway between 1 January 1986 and 30 June 1989 to mothers from surrounding municipalities. Among these children, 14 were diagnosed after birth as having Down's syndrome. A proportion of 85% of the pregnant women in these municipalities had had a routine examination with ultrasound in the 16th to 22nd weeks of gestation at the Ultrasound Laboratory at the Regional Hospital. Ten of the children/fetuses with Down's syndrome in the study population had been subjected to a routine scan. Five of the ten were suspected to have Down's syndrome after the routine scan, and the diagnosis was confirmed by prenatal chromosomal analysis. (All these five fetuses were examined in 1987-88, which means that five of seven were detected in 1987-88). Another two fetuses (out of three) were suspected to have Down's syndrome after an ultrasound scan later in pregnancy. The diagnoses were confirmed by chromosome analyses after birth. One fetus was diagnosed in a 38 year old woman by amniocentesis in the 15th week of gestation. Our study suggests that routine ultrasonic scans can detect a significant proportion of fetuses with Down's syndrome in the second trimester.