Diagnostic Approach for Spontaneous Deep Vein Thrombosis (DVT)

Initial Laboratory Tests

The American College of Chest Physicians recommends a highly sensitive D-dimer test, combined with clinical pretest probability assessment, to guide the diagnostic approach for spontaneous DVT 1, 2
Clinical assessment of pretest probability should guide the diagnostic process, with patients stratified into low, moderate, or high pretest probability of DVT 1, 3

For low pretest probability patients, a moderately or highly sensitive D-dimer test is the preferred initial test, with no further testing needed if D-dimer is negative 4
For moderate pretest probability patients, a highly sensitive D-dimer test is preferred, or proceed directly to ultrasound, with DVT excluded if D-dimer is negative 2, 5
For high pretest probability patients, proceed directly to proximal compression ultrasound or whole-leg ultrasound 5

D-dimer may be falsely elevated in various conditions, including pregnancy, inflammation, malignancy, and advanced age 2
Initial ultrasound testing may be preferred over D-dimer in patients with comorbid conditions likely to cause elevated D-dimer levels 5
In patients with extensive unexplained leg swelling and negative proximal ultrasound, iliac veins should be imaged to exclude isolated iliac DVT 5
For pregnant patients with suspected DVT, initial evaluation with proximal compression ultrasound is recommended over D-dimer testing 6
For suspected upper extremity DVT, initial evaluation with combined modality ultrasound is suggested over D-dimer testing 6