Superficial vein thrombosis is characterized by pain at the site of thrombosis and a reddish, hypothermic cord in the superficial vein with tenderness and surrounding redness and swelling. The diagnosis of superficial vein with a reddish, low-heat cords cannot be made only by clinical manifestation, but also needs to be confirmed by auxiliary examination. 1.Plasma D-dimer assay is often used as the first screening for venous thrombosis, but it can not confirm the diagnosis. Because of the high sensitivity of D-dimer test, but the specificity is poor, it will also be elevated in the case of malignant tumor, trauma, surgery, infection and so on. D-dimer negative predictive value (<500g/L) is mostly used in clinical practice to exclude acute pulmonary embolism and DVT, and when D-dimer becomes positive (>500g/L), it needs to receive further examination. 2.Doppler ultrasonography The sensitivity and accuracy are high, and it is non-invasive diagnosis, which is the preferred method for DVT diagnosis. 3.Spiral CT venous imaging has higher accuracy and more advantages, but high cost. 4.Magnetic resonance venous imaging Can accurately show iliac, femoral and popliteal vein thrombosis, but cannot satisfactorily show calf vein thrombosis. No need to use contrast agent. 5.Venography has high accuracy and can effectively determine not only the presence or absence of thrombus, its location, extent, time of formation and collateral circulation, but also is often used to identify the diagnostic value of other methods, but because it is an invasive test, it should not be used as the first choice, only for patients with negative noninvasive tests and high suspicion of venous thrombosis.