DVT and pulmonary embolism: choosing the right diagnostic tests for patients at risk

The diagnostic approach to venous thromboembolism depends on the clinical setting: Patients with a suspected first episode of DVT can be managed with serial US or IPG. Normal serial results exclude proximal DVT and indicate a low risk for subsequent DVT/PE. Venography is the gold standard and may be indicated if the clinical suspicion differs markedly from the US/IPG result. For patients at high risk for DVT but with no symptoms, there is no accurate noninvasive screening test, but US is superior to IPG and other methods. The diagnostic approach for suspected recurrent DVT is the same as that for a first episode of suspected DVT, providing there is a documented normal US/IPG result since the most recent DVT but prior to presentation. Venography is indicated when the US/IPG is abnormal and there is no knowledge or documentation of a previously normal result. Patients with suspected PE require a V/Q lung scan. Normal results rule out PE, and high probability scans are usually diagnostic of PE. Patients with a nonhigh probability lung scan and a low or moderate pretest probability for PE probably can be managed safely with serial US. When clinical suspicion for PE is high, we recommend venography and--if venography is normal--angiography.