Venous thromboembolism diagnosis

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Venous thromboembolism Diagnosis These
slides were kindly provided by AstraZeneca
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Venous thromboembolism
DVT
PE
Deep vein insufficiency

Post-thrombotic syndrome
Pulmonary hypertension
Death
Ulcus cruris
Chronic PE
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Deep vein thrombosis
Common femoral vein
Thrombus
Proximal
Knee
Distal
Veins of the leg
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Diagnosis of VTE
Clinical diagnosis often uncertain
Diagnosis should be verified objectively

• DVT ultrasonography, venography
• PE scintigram, spiral CT, angiography

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Clinical probability of VTE

• Can be assessed through prediction rules
• Not accurate enough to rule in or out the disease
• Accurate enough to
• refine interpretation of diagnostic tests
• identify a low-risk group in which the diagnostic
  workup may be simplified

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D-dimer

• Specific fibrin degradation product Sign of
  activated coagulation and fibrinolysis
• High sensitivity for VTE (95-99) Nearly all
  with VTE test positive
• High negative predictive value (95-99) Normal
  D-dimer excludes VTE
• Low specificity Positive test does not
  differentiate between VTE or other cause, e.g.
  infection

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Deep vein thrombosis symptoms and signs are
unreliable

• Redness
• Pain
• Oedema/swelling
• Symptoms may be vague or absent

• Increased circumference
• Pain by palpation along the deep vein truncs

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Diagnosis of DVT - venography
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Diagnosis of DVT - ultrasonography
Reflection echoes are translated toproduce a
visual image on a monitor
Transduceremits sound waves
Receivingcrystal
Transmittingcrystal
Sound waves arereflected off internalstructures
Red blood cells
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Diagnosis of DVT - ultrasonography

• Transducer coated in gel is placed on leg
• Transducer is moved along the deep venous system

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Diagnosis of DVT - ultrasonography

• Transducer coated in gel is placed on leg
• Transducer is moved along the deep venous system
• Transducer emits sound waves
• Sound waves are reflected off internal structures
• Reflection echoes are translated to produce a
  visual image on a monitor

Receivingcrystal
Transmittingcrystal
Red blood cells
A Doppler flow study, which uses emitted sound to
detect the direction, velocity and turbulence of
blood flow, is often performed in combination
with compression ultrasonography
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Compression ultrasonography
Artery
Vein
Baseline
Compression
artery
vein
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Compression ultrasonography normal veins
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Doppler ultrasonography normal veins
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Doppler ultrasonography normal veins
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Doppler ultrasonography - DVT
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Compression ultrasonography DVT
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Pulmonary embolism symptoms and signs are
unreliable
Symptoms
Signs

• Cough
• Dyspnea
• Chest pain
• Syncope
• Symptoms may be vague or absent

• Tachycardia
• Hypotension
• Hypo- or hyperventilation
• Low PaO2 normal PaCO2
• Deep vein thrombosis?

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Diagnosis of PE - pulmonary angiography
Complete obstruction of vessel or Filling defect
apparent following injection of contrast medium
Normal lung
Pulmonary embolism
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Diagnosis of PE - pulmonary scintigraphyPerfusion
imaging
Obstructed lungs
Thrombus
ProblemPerfusion abnormalities may be due to
other conditions, e.g. pneumonia
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Diagnosis of PE - pulmonary scintigraphyTwo
types of imaging
Ventilation imaging
Perfusion imaging
Thrombus
ProblemPerfusion abnormalities may be due to
other conditions, e.g. pneumonia
Benefit Eliminates abnormalities due to other
conditions
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Diagnosis of PE - pulmonary scintigraphy
Perfusion scintigram
Mis-match
Ventilation scintigram
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Diagnosis of PE - Spiral Computed Tomography (CT)
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Diagnosis of PE - Spiral Computed Tomography (CT)