Ultrasound signs of acute venous thrombosis

Ultrasound diagnostics of acute venous thrombosis

Acute venous thromboses of the inferior vena cava system are divided into embologenic (floating or non-occlusive) and occlusive. Non-occlusive thrombosis is the source of pulmonary embolism. The superior vena cava system accounts for only 0.4% of pulmonary embolism, the right heart - 10.4%, while the inferior vena cava is the main source of this formidable complication (84.5%).

The lifetime diagnosis of acute venous thrombosis can be established only in 19.2% of patients who died from pulmonary embolism. Data from other authors indicate that the frequency of correct diagnosis of venous thrombosis before the development of fatal pulmonary embolism is low and ranges from 12.2 to 25%.

Postoperative venous thrombosis is a very serious problem. According to V. S. Savelyev, postoperative venous thrombosis develops after general surgical interventions in an average of 29% of patients, in 19% of cases after gynecological interventions and in 38% of transvesical adenomectomy. In traumatology and orthopedics, this percentage is even higher and reaches 53-59%. A special role is given to early postoperative diagnostics of acute venous thrombosis. Therefore, all patients who pose a certain risk in terms of postoperative venous thrombosis should undergo a complete examination of the inferior vena cava system at least twice: before and after surgery.

It is considered fundamentally important to identify the violations of the patency of the main veins in patients with arterial insufficiency of the lower extremities. This is especially necessary for a patient who is supposed to undergo surgical intervention to restore arterial blood flow in the limb; the effectiveness of such surgical intervention is reduced in the presence of various forms of obstruction of the main veins. Therefore, all patients with limb ischemia should have both arterial and venous vessels examined.

Despite the significant advances made in recent years in the diagnosis and treatment of acute venous thrombosis of the inferior vena cava and peripheral veins of the lower extremities, interest in this problem has not diminished in recent years, but is constantly growing. A special role is still given to issues of early diagnosis of acute venous thrombosis.

Acute venous thromboses are divided by their localization into thromboses of the iliac-caval segment, femoropopliteal segment, and thromboses of the veins of the lower leg. In addition, the great and small saphenous veins may be subject to thrombotic damage.

The proximal border of acute venous thrombosis may be in the infrarenal section of the inferior vena cava, suprarenal, reach the right atrium and be in its cavity (echocardiography is indicated). Therefore, it is recommended to begin examination of the inferior vena cava from the area of the right atrium and then gradually move down to its infrarenal section and the place where the iliac veins flow into the inferior vena cava. It should be noted that the closest attention should be paid not only to examining the trunk of the inferior vena cava, but also the veins flowing into it. First of all, these include the renal veins. Usually, thrombotic damage to the renal veins is caused by a volumetric formation of the kidney. It should not be forgotten that the cause of thrombosis of the inferior vena cava can be the ovarian veins or testicular veins. Theoretically, it is believed that these veins, due to their small diameter, cannot lead to pulmonary embolism, especially since the spread of the thrombus to the left renal vein and the inferior vena cava along the left ovarian or testicular vein, due to the tortuosity of the latter, looks casuistic. However, it is always necessary to strive to examine these veins, at least their mouths. In the presence of thrombotic occlusion, these veins slightly increase in size, the lumen becomes heterogeneous and they are well located in their anatomical areas.

With ultrasound triplex scanning, venous thromboses are divided in relation to the lumen of the vessel into mural, occlusive and floating thrombi.

Ultrasound signs of mural thrombosis include visualization of a thrombus with the presence of free blood flow in this area of the altered lumen of the vein, the absence of complete collapse of the walls when the vein is compressed by the sensor, the presence of a filling defect during color Doppler imaging, and the presence of spontaneous blood flow during spectral Doppler imaging.

Thrombosis is considered occlusive if its signs are the absence of wall collapse during vein compression by the sensor, as well as visualization of inclusions of varying echogenicity in the vein lumen, absence of blood flow and vein staining in spectral Doppler and color Doppler modes. Ultrasound criteria for floating thrombi are: visualization of the thrombus as an echogenic structure located in the lumen of the vein with the presence of free space, oscillatory movements of the thrombus apex, absence of contact between the vein walls during compression by the sensor, presence of free space during respiratory tests, enveloping type of blood flow with color coding of the flow, presence of spontaneous blood flow with spectral Doppler.

The possibilities of ultrasound technologies in diagnostics of the age of thrombotic masses are of constant interest. Identification of signs of floating thrombi at all stages of thrombosis organization allows to increase the efficiency of diagnostics. The earliest diagnostics of fresh thrombosis is especially valuable, which allows to take measures of early prevention of pulmonary embolism.

After comparing the ultrasound data of floating thrombi with the results of morphological studies, we came to the following conclusions.

The ultrasound signs of a red thrombus are: hypoechoic fuzzy contour, anechoic thrombus in the apex area and hypoechoic distal part with separate echogenic inclusions. The signs of a mixed thrombus are heterogeneous thrombus structure with hyperechoic clear contour. In the thrombus structure in the distal parts heteroechoic inclusions prevail, in the proximal parts - mainly hypoechoic inclusions. The signs of a white thrombus are: floating thrombus with clear contours, mixed structure with prevalence of hyperechoic inclusions, and fragmentary flows through thrombotic masses are recorded during color Doppler imaging.