The prudent use of diagnostic ultrasound. British Institute of Radiology presidential address 1986.

Progress in diagnostic ultrasound is driven by the development of new technology. The place of new techniques in diagnostic algorithms has to be determined jointly by radiologists and clinicians and appropriate arrangements have to be made for training. About 30 million pounds per year is currently spent on diagnostic ultrasound in the UK. Diagnostic ultrasound depends on the information obtained as a result of ultrasonic irradiation of the patient. Biological effects, some of which are undesirable, can be produced by ultrasound but there is no evidence that the exposures used in diagnosis carry any risk. In judging whether ultrasonic scanning is appropriate in any particular situation, it is necessary to consider benefits, costs and available resources. The costs include not only the costs of the test but also the cost of any hypothetical ultrasonic hazard and the cost of misdiagnosis. The most prudent use of ultrasound is that which maximises the benefit-total-cost ratio and although this cannot presently be quantified, some of the concepts involved can be understood in terms of the health increment and the health decrement, the latter apparently being equal to zero when the diagnosis is correctly made using contemporary equipment. This approach can be extended to introduce the idea of profit arising from the test. As an example, obstetric ultrasound is considered to be appropriate when there is a medical indication for it. Although routine scanning at 16 weeks of pregnancy has been shown to result in a very large profit, there is still conflicting guidance about its advisability on the grounds of safety and existing accounting systems may restrict access to the profit. In discussing the desirability of ultrasonic scanning, patients can be informed that there is no reason to believe that there are any risks related to ultrasonic exposure. The imminent availability of inexpensive ultrasonic scanners for the layman is a worrying prospect to which the medical profession should now try to develop a prudent response.