The use of duplex scanning to diagnose perioperative carotid occlusions.

Perioperative stroke following carotid endarterectomy is reported to occur in 3-20% of patients and may be associated with spontaneous development of thrombus at the operation site or technical imperfections. In 118 consecutive patients, duplex scanning performed immediately before anaesthesia was used to confirm that all high grade carotid stenoses had not progressed to occlusion since the arteriogram. A new technique at completion, using subcuticular prolene sutures for the skin and a plastic dressing for the wound, permitted immediate postoperative assessment by duplex scanning if necessary. Of the 118 patients, symptoms of neurological instability developed in 4 (3.4%) in the first 6 hours after surgery. At duplex scanning, developing thrombus was demonstrated in three of these patients. Arterial thrombus was removed at reoperation and all three patients recovered with no neurological deficit. The fourth patient had occluded the contralateral carotid artery, developed a major stroke and was not considered for re-exploration. Duplex scanning provides accurate diagnostic information in selecting patients for urgent re-exploration, reducing the 24 h stroke rate to 0.8% in this series.