Deep vein thrombosis of the lower extremities: Diagnosis

Anamnesis and physical examination help to identify the likelihood of deep venous thrombosis before the research. The diagnosis is confirmed by Doppler ultrasonography with flow investigation (duplex ultrasonography). The need for additional studies (for example, the study of the content of D-dimer), their choice and consistency depends on the results of ultrasound. No existing research protocol is recognized as the best.

The ultrasound reveals thrombi, directly visualizing the venous wall, and demonstrates the pathological compression properties of the vein, and Doppler ultrasonography - a deteriorated venous flow. The study has a sensitivity of more than 90% and a specificity of more than 95% for thrombosis of the femoral and popliteal veins, but less accurately for iliac thrombosis or thrombosis of the tibia.

If the probability of deep venous thrombosis before the study is moderate or high, it is necessary to determine the D-dimer content simultaneously with duplex ultrasonography. D-dimer is a byproduct of fibrinolysis, an increased amount suggests a recent formation and decomposition of blood clots. The test has a sensitivity of more than 90%, but the specificity is only 5%; Thus, higher figures do not help diagnosis, but the lack of circulating D-dimer allows to exclude deep venous thrombosis, especially when the initial assessment of the probability of deep venous thrombosis is <50%, and the results of duplex ultrasonography are negative. There were cases when against the background of deep venous thrombosis and pulmonary embolism D-dimer was not detected (when using solid-phase enzyme immunoassay). However, more recent methods of latex agglutination or whole blood agglutination (more specific and rapid methods) are likely to allow the use of the D-dimer definition for routine use to exclude deep venous thrombosis when the probability is low or moderate.

Contrast venography is rarely used because an X-ray contrast medication can cause venous thrombosis and allergic reactions, and ultrasound is also atraumatic, more accessible, and with almost the same accuracy, it can detect deep venous thrombosis. Venography is used when the results of ultrasound are normal, but the preliminary studies testify to the benefit of deep venous thrombosis, or when ultrasound reveals a pathology, and the suspicion of deep venous thrombosis is low. The incidence of complications is 2% mainly due to allergic reactions to contrast.

Non-invasive alternatives to contrast venography are at the stage of study. They include magnetic resonance venography and targeted MRI of thrombi, using special techniques, such as the T1-weighted echo image; theoretically the latter can provide simultaneous visualization of thrombi in deep veins and subsegmental pulmonary arteries.

Patients with confirmed deep venous thrombosis and its obvious cause (eg, immobilization, surgery, trauma to the leg) do not need any further examination. If symptoms cause a suspicion of lung. Emboli., use additional research methods (for example, ventilation-perfusion scanning or spiral CT).

Studies to identify hypercoagulability are controversial, but they are sometimes prescribed for patients with idiopathic recurrent deep venous thrombosis, as well as having deep venous thrombosis and a personal or family history of other thromboses and young patients without obvious predisposing factors. Some evidence suggests that the presence of hypercoagulability does not predict the relapse of deep venous thrombosis, as well as clinical risk factors. Screening of patients with deep venous thrombosis for the presence of a malignant tumor has low effectiveness. Routine preventive examination with a full history and physical examination aimed at detecting malignant growth, and certain diagnostic methods of research, appointed based on the results of the survey, is a more appropriate tactic.

[1], [2], [3], [4], [5], [6], [7]