The changing place of radiology in obstetrics.

In 1970 42% of antenatal patients had an X-ray examination (88.6% involving abdominal exposure) but with the introduction of an ultrasound service in 1976 this figure had dropped to 3% by 1980. Looking at the indications for these it can be seen that X rays were still commonly performed for the detection of fetal abnormality and a further reduction in X-ray exposure of pregnant women could be achieved by using ultrasound in this situation. There was a dramatic decline in the use of erect lateral pelvimetry when the fetal presentation was known to be cephalic, especially when the head was engaged, reflecting an increasing awareness by obstetricians that this investigation is unrewarding in clinical practice.