Deep Venous Thrombosis Risk Stratification 

Updated: Oct 30, 2020
Author: Bruce M Lo, MD, MBA, CPE, RDMS, FACEP, FAAEM, FACHE; Chief Editor: Barry E Brenner, MD, PhD, FACEP 

Risk Stratification

The Wells clinical prediction guide quantifies the pretest probability of deep venous thrombosis (DVT) (see Table 1 below). The model enables physicians to reliably stratify patients into high-, moderate-, or low-risk categories. Combining the pretest probability with the results of objective testing greatly simplifies the clinical workup of patients with suspected DVT. The Wells clinical prediction guide incorporates risk factors, clinical signs, and the presence or absence of alternative diagnoses. See Deep Venous Thrombosis for more information.

Table 1. Wells Clinical Score for Deep Venous Thrombosis [1] (Open Table in a new window)

Clinical Parameter

 

Active cancer (treatment ongoing, or within 6 months or palliative

+1

Paralysis or recent plaster immobilization of lower extremities

+1

Recently bedridden for more than 3 days or major surgery less than 4 weeks prior

+1

Localized tenderness along the distribution of the deep venous system

+1

Entire leg swelling

+1

Calf swelling more than 3 cm compared with asymptomatic leg

+1

Pitting edema (greater than asymptomatic leg)

+1

Previous DVT documented

+1

Collateral superficial veins (nonvaricose)

+1

Alternative diagnosis (as likely or greater than that of DVT)

-2

Pretest probability score calculated from the Wells DVT score can be stratified in either 2 or 3 risk groups. In the 3 risk group, patients with a score of 0 or less are considered low risk, 1-2 are moderate risk, and 3 or greater are high risk. In the 2 risk group, patients are stratified as DVT unlikely (Wells score < 2) or DVT likely (Wells score =2). See Table 2 below.

Table 2. Wells Score Risk Stratification Grouped in Either a 2 or 3 Risk Group Scoring System [2, 3] (Open Table in a new window)

Probability (3 Risk Group)

Total Score #

Probability of DVT %

Low risk

 

0

 

5%

Moderate risk

 

1-2

 

17%

High risk

 

>2

 

53%

Probability (2 Risk Group)

Total Score #

Probability of DVT %

Low risk (DVT unlikely)

 

< 2

 

6%

High risk (DVT likely)

 

2

 

28%

This risk group stratification is then considered in concert with the results of a highly sensitive D-dimer assay such an enzyme-linked immunoabsorbent assay (ELISA) or quantitative latex/immunoturbidimetric-based testing.

Using the 2 risk group stratification, if the pretest probability scores as unlikely to have DVT, a negative D-dimer rules out DVT. A positive D-dimer requires a diagnostic study (eg, duplex ultrasonography). If the patient has a negative diagnostic study, DVT is ruled out. If the patient has a positive diagnostic study, the patient should be treated for DVT.

If the pretest probability scores as likely to have a DVT, the patient should have a D-dimer and diagnostic study performed. If the diagnostic study is positive, the patient should be treated for DVT. If the diagnostic study is negative as well as the D-dimer, DVT is ruled out. If the diagnostic study is negative, but the D-dimer is positive, most authors would recommend a repeat diagnostic study in 1 week. If the study is positive, the patient should be treated for DVT; if the study is negative, DVT is ruled out.

See the algorithm below.

Algorithm for deep venous thrombosis (DVT) evaluat Algorithm for deep venous thrombosis (DVT) evaluation using 2 risk stratification Wells criteria. Adapted from Scarvelis et al.

The American College of Physicians (ACP) has created guidelines based on the 3 risk group stratification for first-time DVT.[3] If the pretest probability is low (Wells score =0), a negative D-dimer or diagnostic study (eg, compression ultrasound or whole-leg ultrasound) rules out DVT. If the D-dimer is positive, diagnostic imaging is indicated. If diagnostic imaging is negative, DVT is ruled out. If imaging is positive, then the patient should be treated for DVT. ACP guidelines recommend using D-dimer over diagnostic testing. If diagnostic testing is used, imaging of the proximal leg veins with compression ultrasound is preferred over whole-leg ultrasound.

See the low-risk algorithm below.

Algorithm for deep venous thrombosis (DVT) evaluat Algorithm for deep venous thrombosis (DVT) evaluation using the 3 risk stratification Wells criteria: low risk.

For moderate pretest probability (Wells score 1-2), a D-dimer is recommended. If the D-dimer is negative, the patient has been ruled out for DVT. If the D-dimer is positive, either compression ultrasound of the proximal leg veins or whole-leg ultrasound is indicated. If compression ultrasound of the proximal vein is used and DVT is found, the patient should be treated for DVT. If no DVT is found, the patient should have a repeat ultrasound in 1 week. If whole-leg ultrasound is used and no DVT is found, DVT is ruled out. If a proximal clot is found, the patient should be treated for DVT. If a DVT is found only in the calf vein, treatment should be individualized and have either repeat testing with ultrasound in 1 week to evaluate for possible DVT propagation or treatment for DVT if the patient is unable/unwilling to have a repeat ultrasound. If no treatment is initiated and a repeat ultrasound is done, treatment is only recommended if the DVT has propagated proximally.

See the moderate-risk algorithm below.

Algorithm for deep venous thrombosis (DVT) evaluat Algorithm for deep venous thrombosis (DVT) evaluation using the 3 risk stratification Wells criteria: moderate risk.

For high pretest probability (Wells score >2), imaging is recommended as first-line testing. If imaging is positive for DVT, the patient should be treated for DVT. If whole-leg imaging is negative, the patient has been ruled out for DVT. If compression ultrasound of the proximal veins is negative, a D-dimer can be performed. If negative, the patient has a DVT ruled out; if not, repeat imaging is indicated in 1 week or venography can be performed the same day to rule out DVT.

See the high-risk algorithm below.

Algorithm for deep venous thrombosis (DVT) evaluat Algorithm for deep venous thrombosis (DVT) evaluation using the 3 risk stratification Wells criteria: high risk.

The DVT score was developed in a specific subgroup of patients. Excluded from the model were patients with suspected coexistent pulmonary embolism and patients already taking anticoagulants. Therefore, the evaluation and subsequent treatment of these excluded subgroups must be individualized.[5, 6, 7]

 

Venous Thromboembolism Clinical Practice Guidelines (ASH, 2020)

The American Society of Hematology (ASH) released their updated recommendations on the management of venous thromboembolism (VTE) (deep vein thrombosis [DVT] and pulmonary embolism [PE]) in October 2020.[10] Select recommendations are outlined below.

Strong Recommendations

For patients with PE and hemodynamic compromise, it is recommended that thrombolytic therapy followed by anticoagulation be used over anticoagulation alone.

For patients with DVT and/or PE who have completed primary treatment and will continue vitamin K antagonist (VKA) therapy as secondary prevention, it is recommended that an international normalized ratio (INR) range of 2.0 to 3.0 be used over a lower INR range (eg, 1.5-1.9).

For patients with a recurrent unprovoked DVT and/or PE, indefinite antithrombotic therapy is recommended over stopping anticoagulation after completion of primary treatment.

Conditional Recommendations

Initial management

For patients with DVT and/or PE, the ASH guideline panel suggests using direct oral anticoagulants (DOACs) over VKAs. No single DOAC is suggested over another.

In most patients with proximal DVT, anticoagulation therapy alone is suggested over thrombolytic therapy in addition to anticoagulation.

For patients with PE with echocardiography and/or biomarkers that are compatible with right ventricular dysfunction but without hemodynamic compromise (submassive PE), anticoagulation alone is suggested over the routine use of thrombolysis in addition to anticoagulation.

For patients with extensive DVT in whom thrombolysis is considered appropriate, the ASH guideline panel suggests using catheter-directed thrombolysis over systemic thrombolysis.

For patients with PE in whom thrombolysis is considered appropriate, systemic thrombolysis is suggested over catheter-directed thrombolysis.

For patients with proximal DVT and significant preexisting cardiopulmonary disease, as well as for patients with PE and hemodynamic compromise, use of anticoagulation alone is suggested rather than anticoagulation plus insertion of an inferior vena cava (IVC) filter.

Primary treatment

For primary treatment of patients with DVT and/or PE, whether provoked by a transient risk factor or by a chronic risk factor or unprovoked, using a shorter course of anticoagulation for primary treatment (3-6 months) is suggested over a longer course of anticoagulation for primary treatment (6-12 months).

Secondary prevention

To guide the duration of anticoagulation for patients with unprovoked DVT and/or PE, the ASH guideline panel suggests against routine use of prognostic scores, D-dimer testing, or ultrasonography to detect residual vein thrombosis.

Indefinite antithrombotic therapy is suggested over anticoagulation cessation after completion of primary treatment for the following:

  • Patients with DVT and/or PE provoked by a chronic risk factor
  • Patients with unprovoked DVT and/or PE

For patients with DVT and/or PE who have completed primary treatment and will continue to receive secondary prevention, use of anticoagulation is suggested over aspirin.

For patients with DVT and/or PE who have completed primary treatment and will continue with a DOAC for secondary prevention, the ASH guideline panel suggests using a standard-dose DOAC or a lower-dose DOAC.

Recurrent events

For patients with breakthrough DVT and/or PE during therapeutic VKA treatment, the ASH guideline panel suggests using low-molecular-weight heparin (LMWH) over DOAC therapy.

For patients who develop DVT and/or PE provoked by a transient risk factor and have a history of previous unprovoked VTE or VTE provoked by a chronic risk factor, indefinite antithrombotic therapy is suggested over stopping anticoagulation after completing primary treatment.

For patients who develop DVT and/or PE provoked by a transient risk factor and have a history of a previous VTE also provoked by a transient risk factor, anticoagulation cessation after completion of primary treatment is suggested over indefinite antithrombotic therapy.

Other

For patients with DVT and/or PE with stable cardiovascular disease (CVD) who initiate anticoagulation and were previously taking aspirin for cardiovascular risk modification, it is suggested that aspirin be suspended over continuing it for the duration of anticoagulation therapy.

For patients with DVT, with or without an increased risk for postthrombotic syndrome (PTS), the ASH guideline panel suggests against the routine use of compression stockings.

Additional Resources

For more information, please go to Venous Thromboembolism (VTE), Deep Venous Thrombosis (DVT), and Pulmonary Embolism (PE).

For more Clinical Practice Guidelines, please go to Guidelines.