Floating thrombus in the internal carotid artery disclosed by B-mode ultrasonography.

In a 44-year-old patient with transient cerebral ischaemia a large floating thrombus in the carotid bifurcation was detected by B-mode ultrasonography. To prevent further embolization the floating thrombus was removed by endarterectomy. The sonography findings were confirmed by operation and microscopy. Although migrating clots have long been recognized as a frequent cause of cerebrovascular accident, comparable cases have been rarely published. The problems involved in visualizing thrombi in the carotid artery by B-mode ultrasonography are discussed.