Audit of the effect of introducing local guidelines for referral for carotid duplex scanning.

Guidelines for referral of patients for carotid duplex scanning were introduced stating that scans were only indicated for patients with hemispheric localising symptoms or asymptomatic bruits. A 19% reduction in referral rate was seen for new scans in a one year period. The number of "inappropriate" requests fell from 27.6% in 1994 to 12.8% in 1995. There was no reduction in the numbers of patients identified with effectively occult asymptomatic disease who may have been suitable for surgery in the same period. Guideline introduction had the effect of reducing unnecessary scans without any effect on the overall pick-up, rate for carotid disease.