DVT: Symptoms and work-up
Sean Stoneking
DVT Epidemilogy
• Approximately 600,0000 new cases of DVT each year
• 50% in hospitalized patients or nursing home residents
Clinical Signs and Symptoms
• Up to 50% are asymptomatic
• Pain
• Edema
• Warmth
• Discoloration
• Palpable cord of a thrombosed vein
• Homan’s sign (present 1/3 of cases)
DDx of acute edema/leg pain?
• Infection
• Trauma/injury
• Venous insufficiency
Risk Factors: Virchow’s Triad
• Stasis
• Venous endothelial injury
• Hypercoagulable state
Risk factors
• Past DVT• Immobilization• Pregnancy• OCP and HRT• Trauma• Obesity• Age• Sepsis• Cancer• Diseases that alter blood viscosity (sickle cell,
polycythemia, multiple myeloma)
Risk Factors: Thrombophilias
• Anticoagulant protein deficiency (Protein C/S, Antithrombin Plasminogen, Heparin cofactor II)
• Dysfibrinogenemia
• Antiphospholipid antibodies
• Factor V Leiden mutation (heterozygous)
• Prothrombin G20210A mutation (heterozygous)
Wells pretest probability
Clinical features1. Active cancer (treatment within 6 months)2. Paralysis, paresis, or immobilization of lower extremity3. Bedridden for more than 3 days because of surgery
(within 4 weeks)4. Localized tenderness along distribution of deep veins5. Entire leg swollen6. Unilateral calf swelling of greater than 3 cm (below
tibial tuberosity)7. Unilateral pitting edema8. Collateral superficial veins9. Alternative diagnosis as likely as or more likely than
DVT
Points
1
1
1
1
1
1
1
1
-2
Pretest Probability Interpretation
• >=3 points: high risk (75%)
• 1 to 2 points: moderate risk (17%)
• <1 point: low risk (3%).
Ramzi and Leeper, Am Fam Phys 2004;69 (12).
Testing Modalities
• Ulrasonography
• D-dimers
• Contrast venography
• MRI
• Spiral CT
Ultrasound
• In the proximal veins sensitivity is 97%
• In the calf veins sensitivity is only 73%
• It cannot distinguish between an old clot and a new clot.
D-dimers
• Degradation product of a cross-linked fibrin blood clot.
• Levels also elevated in recent major surgery, hemorrhage, trauma, pregnancy or cancer.
• Sensitive but nonspecific
• The value is in a negative test result
Contrast venography
• “Gold Standard” for imaging DVT • can image entire lower extremities• Sensitive in asymptomatic patients• Limitations: invasive, contrast
reactions
MRI
• Good test for suspected iliac vein or inferior vena caval thrombosis
• More sensitive than any other noninvasive study in suspected calf vein thrombosis.
• Expense, lack of general availability
Spiral CT
• When PE is suspected, can scan chest and lower extremities with same amount of contrast.
• ~50% more costly than ultrasound
• Risk of contrast reaction
Summary
• Use risk stratification of H&P with diagnostic testing to make the diagnosis
• Up to 50% of pts with DVT are asymptomatic• Negative D-dimer rules out DVT in low
probability• Ultrasound useful for diagnosing proximal
thromboses• MRI and contrast venography useful for
diganosing distal thromboses
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