cardiovascular disorders
Deep Venous Thrombosis (DVT)
Diagnosis of Deep Venous Thrombosis
Ultrasonography Sometimes D-dimer testing History and physical examination help determine probability of DVT before testing (see table). Diagnosis is typically by ultrasonography with Doppler flow studies (duplex ultrasonography). The need for additional tests (eg, D-dimer testing) and their choice and sequence depend on pretest probability and sometimes ultrasonography results. No single testing protocol is best; one approach is described in the figure. 95% specific for femoral and popliteal vein thrombosis but is less accurate for iliac or calf vein thrombosis ( Diagnosis references ). D-Dimer is a byproduct of fibrinolysis; elevated levels suggest recent presence and lysis of thrombi. D-Dimer assays vary in sensitivity and specificity; however, most are sensitive and not specific. A positive test result is nonspecific because levels can be elevated by other conditions (eg, liver disease, trauma, pregnancy, positive rheumatoid factor, inflammation, recent surgery, cancer), and further testing is necessary. Only the most accurate tests should be used. For example, a highly sensitive test is enzyme-linked immunosorbent assay (ELISA), which has a sensitivity of about 95% ( Diagnosis references ). D-dimer levels also increase with age, which further decreases the specificity in older patients ( The Pulmonary Embolism Graduated D-dimer (PEGeD) strategy is a diagnostic approach for pulmonary embolism that adjusts for D-dimer levels according to the patient's clinical pretest probability( Diagnosis references ): If pretest probability of DVT is low,DVT can generally be excluded in patients with a D-dimer level<1000 ng/mL(<5476 nmol/L) on a sensitive test. If pretest probability of DVT is moderate, DVT can be excluded in patients with a normal D-dimer level (ie, < 500 ng/mL) on a sensitive test. Patients with a positive test require additional testing to rule out DVT. If pretest probability of DVT is high,D-dimer testing can be done at the same time as duplex ultrasonography. A positive ultrasound result confirms the diagnosis regardless of the D-dimer level. If ultrasonography does not reveal evidence of DVT, a normal D-dimer level helps exclude DVT. Patients with an elevated D-dimer level should have repeat ultrasonography in a few days or additional imaging, such as venography, depending on clinical suspicion. If symptoms and signs suggest PE, additional imaging (eg, CT pulmonary angiography or, less often, ventilation/perfusion [V/Q] scanning) is required. Contrast-enhanced computed tomographic venography and magnetic resonance venography are other imaging modalities rarely used in the diagnosis of DVT. They are generally reserved for cases in which ultrasonography results are negative or indeterminate and the clinical suspicion for DVT remains high. These imaging tests are less well validated for DVT, are more costly, and may be associated with other complications (eg, related to exposure to radiation and contrast agents). Contrast venography was the definitive test for the diagnosis of DVT in the past but has been largely replaced by ultrasonography, which is noninvasive, more readily available, and almost equally accurate for detecting DVT. Patients with confirmed DVT and an obvious cause (eg, immobilization, surgical procedure, leg trauma) need no further testing. Diagnosis is controversial but is sometimes done in selected patients who have idiopathic (or unprovoked) DVT or recurrent DVT, in patients who have a personal or family history of other thromboses, and in young patients with no obvious predisposing factors. Some evidence suggests that testing for the presence of hypercoagulability in patients with or without clinical risk factors does not predict DVT recurrence ( Screening patients with DVT for cancer has a low yield. Selective testing guided by complete history and physical examination and basic "routine" tests (complete blood count, chest x-ray, urinalysis, liver enzymes, and serum electrolytes, bloodureanitrogen [BUN], creatinine) aimed at detecting cancer is probably adequate. In addition, patients should have any appropriate cancer screening (eg, mammography, colonoscopy) that is due. 1.Lensing AW, Prandoni P, Brandjes D, et al. Detection of deep-vein thrombosis by real-time B-mode ultrasonography.N Engl J Med1989;320(6):342-345. doi:10.1056/NEJM198902093200602 2.Di Nisio M, Squizzato A, Rutjes AW, Büller HR, Zwinderman AH, Bossuyt PM. Diagnostic accuracy of D-dimer test for exclusion of venous thromboembolism: a systematic review [published correction appears inJ Thromb Haemost2013 Oct;11(10):1942].J Thromb Haemost2007;5(2):296-304. doi:10.1111/j.1538-7836.2007.02328.x 3.Righini M, Van Es J, Den Exter PL, et al. Age-adjusted D-dimer cutoff levels to rule out pulmonary embolism: the ADJUST-PE study [published correction appears in JAMA. 2014 Apr 23-30;311(16):1694].JAMA2014;311(11):1117-1124. doi:10.1001/jama.2014.2135 4.Kearon C, de Wit K, Parpia S, et al. Diagnosis of Pulmonary Embolism with d-Dimer Adjusted to Clinical Probability.N Engl J Med2019;381(22):2125-2134. doi:10.1056/NEJMoa1909159 5.Coppens M, Reijnders JH, Middeldorp S, Doggen CJ, Rosendaal FR. Testing for inherited thrombophilia does not reduce the recurrence of venous thrombosis.J Thromb Haemost2008;6(9):1474-1477. doi:10.1111/j.1538-7836.2008.03055.x 6.Lijfering WM, Middeldorp S, Veeger NJ, et al. Risk of recurrent venous thrombosis in homozygous carriers and double heterozygous carriers of factor V Leiden and prothrombin G20210A.Circulation2010;121(15):1706-1712. doi:10.1161/CIRCULATIONAHA.109.906347 7.Segal JB, Brotman DJ, Necochea AJ, et al. Predictive value of factor V Leiden and prothrombin G20210A in adults with venous thromboembolism and in family members of those with a mutation: a systematic review.JAMA2009;301(23):2472-2485. doi:10.1001/jama.2009.853 