What is the evaluation for Deep Vein Thrombosis (DVT)?

From the Guidelines

Deep vein thrombosis (DVT) evaluation should begin with compression ultrasonography of the proximal deep veins as the preferred initial imaging modality, given its high sensitivity and specificity for diagnosing proximal DVT, as evidenced by a recent meta-analysis showing a pooled sensitivity of 94.2% and pooled specificity of 93.8% 1. When evaluating for DVT, it is crucial to consider the location and extent of the suspected thrombosis. Key points to consider in the evaluation process include:

• The use of compression ultrasonography for its ability to identify the failure of complete compression of vein walls when pressure is applied to the skin during real-time imaging, which is a major sonographic criterion for DVT 1.
• The incorporation of real-time Doppler imaging, such as duplex, continuous-wave, and color-flow Doppler imaging, to characterize a clot as obstructive or partially obstructive 1.
• The recognition of the limitations of ultrasonography, particularly in diagnosing distal DVT, where sensitivity is significantly lower, ranging from 59.8% to 67.0% 1.
• The potential use of magnetic resonance venography (MRV) as a noninvasive alternative to contrast catheter venography, especially for identifying extravascular anatomy and potential sources of extrinsic venous compression 1.
• The importance of considering clinical context, such as pregnancy or contraindications to standard imaging, when selecting an appropriate imaging modality 1. In terms of diagnostic criteria, the presence of a distinct filling defect in a deep vein on imaging, typically in the calf or thigh, is indicative of DVT 1. Less specific findings may include an abrupt contrast cutoff, the absence of contrast filling, or the presence of collateral venous vessels. Given the high stakes of missing a DVT diagnosis, a systematic approach that prioritizes compression ultrasonography as the initial imaging modality, followed by consideration of additional diagnostic tools as needed, is recommended 1.

From the FDA Drug Label

The primary efficacy endpoint was confirmed, symptomatic, recurrent VTE reported up to Day 97. The efficacy data are provided in Table 12. Table 12. Efficacy of Fondaparinux Sodium in the Treatment of Deep Vein Thrombosis (All Randomized) Endpoint Fondaparinux Sodium 5,7.5, or 10 mg SC once daily N = 1,098 Enoxaparin Sodium 1 mg/kg SC every 12 hours N = 1,107 n % (95% CI) n % (95% CI) Total VTE a 43 3.9% (2.8,5.2) 45 4.1% (3.0,5.4) DVT only 18 1.6% (1.0,2.6) 28 2.5% (1.7,3.6) Non-fatal PE 20 1.8% (1.1,2.8) 12 1.1% (0.6,1.9) Fatal PE 5 0.5% (0.1.1) 5 0.5% (0.1.1)

The evaluation for Deep Vein Thrombosis (DVT) includes assessing the efficacy of fondaparinux sodium and enoxaparin sodium in preventing recurrent VTE.

• The primary efficacy endpoint is confirmed, symptomatic, recurrent VTE reported up to Day 97.
• Key findings include:
  • Fondaparinux sodium was associated with a Total VTE rate of 3.9% compared to 4.1% for enoxaparin sodium.
  • Fondaparinux sodium was associated with a DVT only rate of 1.6% compared to 2.5% for enoxaparin sodium.
  • Fondaparinux sodium was associated with a Non-fatal PE rate of 1.8% compared to 1.1% for enoxaparin sodium.
  • Fondaparinux sodium was associated with a Fatal PE rate of 0.5% compared to 0.5% for enoxaparin sodium. 2

From the Research

Evaluation of Deep Vein Thrombosis (DVT)

The evaluation of DVT involves a multifaceted approach that includes clinical assessment, evaluation of pre-test probability, and objective diagnostic testing 3, 4.

• Clinical assessment: Common symptoms and signs of DVT are pain, swelling, erythema, and dilated veins in the affected limb 4.
• Evaluation of pre-test probability: The pre-test probability of DVT can be assessed using a clinical decision rule that stratifies DVT into "unlikely" or "likely" 4.
• Objective diagnostic testing:
  • D-dimer test: A normal D-dimer level excludes DVT when combined with a low pretest probability 3, 4, 5.
  • Compression ultrasound: Compression sonography with color Doppler remains the best overall test for DVT 6.
  • Other diagnostic studies: Contrast venogram, CT or MRI venogram, Tc99m Apcitide study, and laboratory test D-Dimer 6.

Diagnostic Criteria

The diagnostic criteria for DVT include:

• Wells score or modified Wells score to determine the likelihood of DVT 3.
• A low or moderate probability score and a normal D-dimer test result exclude DVT 3.
• If the score indicates that DVT is likely, patients should undergo Doppler ultrasonography (US) 3.
• If US reveals DVT in a proximal vein, anticoagulation should be started unless contraindicated 3.

Treatment

The treatment of DVT includes:

• Anticoagulation: Direct oral anticoagulants are recommended for most patients except pregnant women, for whom heparins are recommended 3, 4, 5.
• Treatment duration: The treatment duration is at least 3 months, and longer if risk factors persist 3.
• Other treatments: Thrombectomy, thrombolytics, and vena cava filters are used for select patients 3, 5.