The incidence of DVT in ED patients who had urgent after-hours DVS was no different than in those whose DVS was delayed until regular hours. High pretest probability can be achieved with clinical evaluation prior to DVS, and this guided the decision to prophylactically anticoagulate but did not impact the decision to perform urgent DVS. Most patients eventually found to have DVT did receive prophylactic anticoagulation, and delay of DVS did not result in complications. We believe that most patients in whom there is high clinical suspicion for DVT can safely get prophylactic anticoagulation and delayed DVS. Patients in whom there is low clinical suspicion should not get urgent DVS.

We conclude that ≥ 50% stenosis and ≥ 70% stenosis can be reliably determined by CDU in our vascular laboratory. Each vascular laboratory must validate their own criteria against the current gold standard of carotid arteriography. A high degree of confidence in CDU is critical before any institution uses the test as the sole diagnostic method prior to carotid intervention.

Carotid duplex (CD) scanning is the primary method of evaluating patients suspected of having extracranial carotid occlusive disease. It is incumbent on vascular laboratories (VL) to have internally validated criteria confirming overall accuracy, specificity (SP), sensitivity (SS), negative predictive value (NPV), and positive predictive value (PPV). Receiver operating characteristic (ROC) curves allow further analysis to update existing criteria. We correlated 127 internal carotid arteries studied by carotid duplex scanning and confirmatory modalities, which showed a SP of 83.3%, SS of 97.9%, NPV of 92.5%, PPV of 95%, and overall accuracy of 94.5% for >50% internal carotid artery stenosis. For >70% stenosis, SP was 88.8%, SS was 96.1%, NPV was 93.6%, PPV was 92.5%, and overall accuracy was 92.9%. ROC curves for the peak systolic velocities were used; for detecting a 50-69% stenosis range a sensitivity of 88%, specificity of 93%, NPV of 73%, and PPV of 97% were found. For detecting a 70-99% stenosis a sensitivity of 95%, specificity of 90%, NPV of 93%, and a PPV of 93% were found. All vascular laboratories must have a vigorous quality assurance program and must validate their own internal criteria or the recently promulgated consensus criteria for grading the severity of carotid stenosis by carotid duplex examination.