Dvt diagnosis

Appropriate methods for diagnosing deep vein thrombosis (DVT) begin with a thorough clinical assessment including history and physical examination to exclude other causes of leg symptoms such as swelling or pain. The two-level DVT Wells score is recommended to estimate the clinical probability of DVT, assigning points for risk factors and clinical signs, with a score of 2 or more indicating DVT is likely, and 1 or less indicating DVT is unlikely NICE NG158.

For people with a likely DVT (Wells score ≥2), a proximal leg vein ultrasound scan should be offered with results ideally available within 4 hours. If ultrasound cannot be performed within 4 hours, a D-dimer test should be done, followed by interim therapeutic anticoagulation and a repeat ultrasound within 24 hours NICE NG158.

For those with an unlikely DVT (Wells score ≤1), a D-dimer test is recommended with results available within 4 hours. If the D-dimer is negative, DVT can be excluded and anticoagulation stopped. If positive, a proximal leg vein ultrasound scan should be performed within 4 hours or, if delayed, interim anticoagulation started while awaiting ultrasound within 24 hours NICE NG158.

The D-dimer test is highly sensitive but not specific; a negative result effectively excludes DVT in low clinical probability cases, but a positive result requires further imaging as it can be elevated in other conditions such as inflammation, malignancy, or pregnancy NICE NG158,NICE CKS. Age-adjusted D-dimer thresholds and fully quantitative point-of-care D-dimer tests are recommended to improve diagnostic accuracy NICE NG158.

Ultrasound imaging remains the gold standard for confirming DVT, particularly proximal leg vein ultrasound. If the initial ultrasound is negative but the D-dimer is positive, a repeat ultrasound 6 to 8 days later is advised to detect any developing thrombosis NICE NG158.

In pregnant or postpartum women, immediate referral for same-day assessment is recommended without reliance on Wells score or D-dimer testing, as these are less validated in this population NICE NG158,NICE CKS.

Recent literature on upper extremity DVT diagnosis emphasizes the importance of ultrasound imaging as the primary diagnostic tool, consistent with lower limb DVT guidelines, and highlights the limited role of clinical prediction rules alone, reinforcing the integrated approach of clinical assessment, D-dimer testing, and imaging Kraaijpoel et al. 2017.