The antenatal diagnosis of fetal abnormalities: a 10 year audit of influencing factors.

During the 10 years 1984-1993, a total of 438 fetuses and children with a congenital abnormality, identified antenatally or in the first year of life, were registered from the North Tees Health District with the Northern Region Congenital Abnormality Survey (NorCAS). This represented an abnormality rate of 2% of all births. In total, 252 structural abnormalities (57.5%) were detected by antenatal ultrasound examination. In spite of a targeted education programme, identification of cardiac lesions remained poor. The detection of structural abnormality by antenatal scan rose from 52% in 1984 to 85% in 1993, due mainly to improvements in image quality and resolution of ultrasound equipment. Also important was audit, based both on review of images and feedback from a comprehensive central register (NorCAS).