DVT: Symptoms and work-up

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DVT Symptoms and work-up

• Sean Stoneking

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DVT Epidemilogy

• Approximately 600,0000 new cases of DVT each year
• 50 in hospitalized patients or nursing home
  residents

3
Clinical Signs and Symptoms

• Up to 50 are asymptomatic
• Pain
• Edema
• Warmth
• Discoloration
• Palpable cord of a thrombosed vein
• Homans sign (present 1/3 of cases)

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DDx of acute edema/leg pain?

• Infection
• Trauma/injury
• Venous insufficiency

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Risk Factors Virchows Triad

• Stasis
• Venous endothelial injury
• Hypercoagulable state

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Risk factors

• Past DVT
• Immobilization
• Pregnancy
• OCP and HRT
• Trauma
• Obesity
• Age
• Sepsis
• Cancer
• Diseases that alter blood viscosity (sickle cell,
  polycythemia, multiple myeloma)

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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)

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Wells pretest probability

• Clinical features
• 1. Active cancer (treatment within 6 months)
• 2. Paralysis, paresis, or immobilization of lower
  extremity
• 3. Bedridden for more than 3 days because of
  surgery (within 4 weeks)
• 4. Localized tenderness along distribution of
  deep veins
• 5. Entire leg swollen
• 6. Unilateral calf swelling of greater than 3 cm
  (below tibial tuberosity)
• 7. Unilateral pitting edema
• 8. Collateral superficial veins
• 9. Alternative diagnosis as likely as or more
  likely than DVT

• Points
• 1
• 1
• 1
• 1
• 1
• 1
• 1
• 1
• -2

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Pretest Probability Interpretation

• gt3 points high risk (75)
• 1 to 2 points moderate risk (17)
• lt1 point low risk (3).

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Ramzi and Leeper, Am Fam Phys 200469 (12).
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Testing Modalities

• Ulrasonography
• D-dimers
• Contrast venography
• MRI
• Spiral CT

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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.

13
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

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Contrast venography

• Gold Standard for imaging DVT
• can image entire lower extremities
• Sensitive in asymptomatic patients
• Limitations invasive, contrast reactions

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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

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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

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Summary

• Use risk stratification of HP 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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Location of DVT
Scarvelis, D. et al. CMAJ 20061751087-1092