Clinical correlates of Doppler/ultrasound errors in the detection of internal carotid artery occlusion.

One recognized limitation of carotid Doppler/ultrasound is its accuracy in differentiating occlusion from near-total occlusion of the internal carotid artery, which is a crucial issue in management decisions. Clinical histories were reviewed in 58 patients with apparent occlusion of an internal carotid artery diagnosed by Doppler/ultrasound who also underwent angiography. False-positive results were detected in eight patients, for an overall accuracy of 86%. Among a group of 25 patients with acute cerebral or ocular events ipsilateral to an apparently occluded artery, false-positive results occurred in seven (accuracy of 72%). Among a group of 33 patients with asymptomatic or remotely symptomatic apparent occlusions, only one false-positive occurred, for an accuracy of 97%. This difference in accuracy between groups was significant. Thus, a Doppler/ultrasound diagnosis of occlusion was most inexact in those patients for whom the detection of continued patency was most likely to influence management.