Carotid duplex scanning: patterns of referral and outcome

Abstract

Objective: Review of the results of carotid Duplex scanning.

Design: Retrospective review of new referrals for carotid Duplex scanning to a regional vascular laboratory.

Materials: 1041 referrals made over an 18 month period.

Methods: Referrals were reviewed for scan quality, diagnostic category and outcome of scanning.

Results: The overall detection rate of ipsilateral stenoses > 70% and occlusions was 13.5%; the detection rate of surgically significant carotid lesions (70-99%) was only 8%. Analysis by diagnostic category revealed a significantly greater detection rate for carotid lesions > 70% in patients presenting with amaurosis fugax (24%) in comparison to those with TIAs (9.5%, p = 0.0005) or following a stroke (13%, p = 0.01). Patients referred with asymptomatic bruits or prior to cardiac surgery showed a positive scan rate of 30%. Sixty-seven carotid endarterectomies have resulted from scans performed in this period.

Conclusion: The overall rate of detection for surgically relevant lesions is low, but in comparison to a similar audit conducted in 1992, the absolute number of carotid lesions > 70% has risen by 60%. An 8% detection rate for surgically relevant lesions may be valuable in projecting the need for carotid endarterectomy arising from a given number of Duplex scans.