Determining the clinical probability of deep venous thrombosis and pulmonary embolism.

Deep venous thrombosis and pulmonary embolism are potentially life-threatening problems that present diagnostic challenges. To employ objective diagnostic tests in an efficient, safe, and cost-effective manner, the clinical probability of these disorders should be estimated before testing. A number of clinical prediction rules are available for suspected deep venous thrombosis, while there are three major prediction rules available for estimating the probability of pulmonary embolism. Recent modifications of the Wells score for deep venous thrombosis simplify its use. Although the Wells score for pulmonary embolism is commonly used, two other rules are useful for this disorder as well. This review summarizes the clinical prediction rules and gives recommendations about their application.