Mark H. Meissner, MD

The diagnosis of venous thromboembolismon the basis ofclinical signs and symptoms isnotoriously inaccurate and, therefore,mandates confirmatory diagnostictesting. Unfortunately, all diagnostictests for deep venous thrombosis(DVT) and pulmonary embolismhave clinical or practical limitations.Contrast venography and pulmonaryarteriography are usually regarded asthe reference standards for the diagnosisof DVT and pulmonary embolism,respectively. However, evencontrast venography may be impossibleto perform in 9% to 14% ofpatients, may fail to visualize 10% to30% of venous segments, and maybe associated with postvenographythrombosis in up to 8% of patients.[1]