Chapter 111. Venous Thrombosis (Part 4)

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Deep Vein Thrombosis The signs and symptoms of DVT, such as swelling, pain, redness, superficial venous dilatation, and Homan's sign (pain in the calf or behind the knee on dorsiflexion of the ankle), are nonspecific and consequently insufficient for ruling the disease in or out. The classic "gold standard" is contrast venography. Although very accurate, this method requires radiologic facilities and expertise and is invasive and sometimes uncomfortable for the patient. Ultrasonography, with noncompressibility of the vein as the sole criterion, has largely replaced contrast venography. The investigation is limited to the femoral vein in the groin and the popliteal...

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Chapter 111. Venous Thrombosis (Part 4) Deep Vein Thrombosis The signs and symptoms of DVT, such as swelling, pain, redness, superficial venous dilatation, and Homan's sign (pain in the calf or behind the knee on dorsiflexion of the ankle), are nonspecific and consequently insufficient for ruling the disease in or out. The classic "gold standard" is contrast venography. Although very accurate, this method requires radiologic facilities and expertise and is invasive and sometimes uncomfortable for the patient. Ultrasonography, with noncompressibility of the vein as the sole criterion, has largely replaced contrast venography. The investigation is limited to the femoral vein in the groin and the popliteal vein in the popliteal fossa. This method has a very high sensitivity and specificity (95–100%) in symptomatic patients for proximal DVT. For isolated DVT in the calf veins the method is less accurate. This latter characteristic of compression ultrasonography explains the necessity of repeating
the test after ~1 week in those patients with an initial normal test result in order to detect extending calf thrombi. However, the first objective of the diagnostic workup was to rule out DVT quickly and safely. For this purpose the combination of the assessment of clinical probability and the measurement of the D-dimer blood concentration has been shown to be very useful. The clinical probability can be best assessed by the rule shown in Table 111-2, which results in a classification of either DVT likely or DVT unlikely. D-Dimer is a degradation product of cross- linked fibrin and therefore concentrations of D-dimer below a certain cut-off level are considered to indicate the absence of thrombosis. Elevations of D-dimer in patients > 70 years who do not have thrombosis make the test less useful in this population. Table 111-2 Clinical Decision Rule for Diagnosing Thrombosis Decision rule for clinically suspected deep vein thrombosis Points (DVT) Active cancer (patient receiving treatment for cancer within 1 the previous 6 months or currently receiving palliative treatment) Paralysis, paresis, or recent plaster immobilization of the 1
lower extremities Recently bedridden for ≥3 days or major surgery within the 1 previous 12 weeks requiring general or regional anesthesia Localized tenderness along the distribution of the deep 1 venous system Entire leg swollen 1 Calf swelling at least 3 cm larger than that on the 1 asymptomatic side (measured 10 cm below tibial tuberosity) Pitting edema confined to the symptomatic leg 1 Collateral superficial veins (nonvaricose) 1 Previously documented deep vein thrombosis 1 Alternative diagnosis at least as likely as deep vein –2
thrombosis Score 100/min 1.5 Immobilization (>3 days) or surgery in the previous 4 weeks 1.5 Previous pulmonary embolism or deep vein thrombosis 1.5 Hemoptysis 1
Malignancy (receiving treatment, treated in the last 6 months 1 or palliative) Score ≤4: PE unlikely >4: PE likely