Ultrasound diagnosis of venous thrombosis in an outpatient setting

The formation of a blood clot in the popliteal vessel is a type of venous thromboembolism. This is a serious condition that can lead to life-threatening complications such as pulmonary embolism. The popliteal vein runs under the knee joint and transports blood back to the heart. When a blood clot forms in this vein, doctors call it popliteal vein thrombosis.

Symptoms include pain, swelling and redness in the leg and knee area. Popliteal vein thrombosis can occur due to poor blood flow, damage to a blood vessel, or external trauma.

What is popliteal vein thrombosis?

When blood clots, it forms a blood clot (thrombus). Blood clotting occurs in response to injuries that cause bleeding. The blood clot closes the wound and stops bleeding, preventing further blood loss and beginning the healing process. When a blood clot forms inside a vein or artery, doctors call it thrombosis. Thrombosis can develop due to poor blood flow, external damage to blood vessels, or external injuries. This is a serious condition because it can cause a blockage that stops blood flow completely.

The popliteal vein is one of several blood vessels that carry blood from the lower extremities to the inferior vena cava, which carries blood from the lower body to the heart. Popliteal vein thrombosis is a type of venous thromboembolism (VTE), also called deep vein thrombosis (DVT). This is potentially life-threatening as the clot can break off and travel through the heart to the lungs. A blood clot that reaches the lungs is known as a pulmonary embolism (PE).

Thrombophlebitis is a dangerous complication of varicose veins

Slow movement of blood through the superficial veins, as well as damage to the vascular walls (and sprains often lead to them) are two factors that play a big role in the formation of thrombophlebitis of the lower extremities. Symptoms of this disease are pain in the leg, redness, and thickening along the vein. All this is a consequence of the formation of a thrombus, a blood clot in the lumen of the vessel. Often, a blood clot can completely close a vein. The detachment of a blood clot is also dangerous, since in this case it can block another vessel, for example, the pulmonary artery.

Thrombophlebitis is a disease of the superficial veins, which is most often a complication of varicose veins. If the disease occurs on its own, without previous varicose veins, the cause is usually disturbances in the functioning of the blood coagulation system. Symptoms of thrombophlebitis without varicose veins always attract the attention of doctors, and this situation requires additional examinations.

Let us emphasize once again that everything described applies to superficial veins. If we are talking about thrombophlebitis of the deep veins of the lower extremities, symptoms and treatment... Can we talk about this disease?

Thrombosis of the popliteal vein - symptoms

Symptoms of popliteal vein thrombosis may include:

• redness in the knee or calf area;
• swelling of the knee joint and foot;
• increased temperature in the popliteal fossa or in the foot;
• pain in the knee joint and foot, which may feel like a cramp.

You should immediately consult a doctor if the following symptoms occur along with potential popliteal vein thrombosis:

• shortness of breath;
• chest pain;
• coughing up blood.

Causes and risk factors

Sometimes there is no obvious cause for popliteal vein thrombosis, but various factors can increase the risk of developing it. In particular, anything that can reduce blood flow to this area can increase the risk of popliteal vein thrombosis. When blood does not circulate properly, it can accumulate in a vein, forming a blood clot.

Factors that may reduce blood flow include:

• immobility for a long time;
• smoking;
• obesity;
• pregnancy.

Medical conditions that may increase the risk of blood clotting include:

• certain types of cancer;
• broken leg or hip;
• spinal cord injuries;
• heart disease and stroke;
• phlebeurysm;
• previous VTE;
• family history of VTE;
• genetic diseases that affect blood clotting, such as thrombophilia, antiphospholipid syndrome and sickle cell anemia.

Damage to the vein is possible after surgery or serious trauma to the lower extremity, and sometimes this can lead to the formation of popliteal vein thrombosis. Birth control, hormone replacement therapy, and other medications that contain estrogen may also increase the risk of blood clots. Increasing age is another risk factor for blood clotting. The risk of VTE nearly doubles every 10 years after age 40.

Thrombophlebitis or thrombosis?

If blood clots form in the deep veins of the lower extremities, then we are not talking about thrombophlebitis, but about thrombosis. What is the difference between these two diseases?

Thrombophlebitis is a disease that occurs mainly as a result of injury to the vein wall. It is accompanied by inflammation, which, together with a slowdown in blood flow, causes the formation of blood clots. Venous thrombosis of the lower extremities is a disease caused by a malfunction of the blood coagulation system. It is not associated with varicose veins, nor is it preceded by damage to the veins, although the presence of injuries increases the risk of thrombosis. And it poses no less danger to the body than thrombophlebitis, since there is a possibility of blocking blood flow or breaking off a blood clot.

Among the factors contributing to the development of thrombosis are:

• elderly age
• increased body weight, decreased physical activity
• taking oral contraceptives
• pregnancy (during this period, a woman’s blood clotting properties may change)
• smoking
• surgical operations

Diagnostics

To diagnose popliteal vein thrombosis, the doctor performs a physical examination of the affected area and checks the person's heart rate. To clarify the diagnosis, the doctor may refer the patient to:

Ultrasound

The doctor may use an ultrasound to examine the popliteal and calf areas and check for signs of a blood clot. Ultrasound uses high-frequency sound waves to create images of the inside of the veins.

CT scan

CT scan takes pictures of internal organs. Your doctor may use CT scans to check for blood clots in your veins. The doctor may also check the chest for signs of TE, which can happen when a blood clot travels to the lungs.

D-dimer test

This test requires blood to check the level of D-dimer, a type of protein that can be an indicator of blood clotting. However, this test can sometimes give false-positive results, especially if the person has previously had VTE or has certain medical conditions, including:

• rheumatological;
• heart failure;
• cancer;
• inflammation.

Popliteal vein thrombosis - treatment

There are several different treatment options for VTE, including:

Anticoagulants

Doctors usually prescribe anticoagulant drugs to people with VTE. Anticoagulants, also known as blood thinners, prevent blood clots, help prevent new clots from forming, and reduce the risk of developing PE.

Anticoagulant drugs include:

• heparin;
• warfarin;
• newer anticoagulants such as rivaroxaban, apixaban and dabigatran.

Initially, an oral anticoagulant is prescribed 1 or 2 times a day for 5-21 days. Doctors may also recommend that a patient take these medications long-term to prevent future blood clots. Treatment may last 6 months or longer. Anticoagulants may cause side effects, which may include bleeding. People who experience side effects or other problems while taking these medications should talk to their doctor.

Kava filter

Doctors may recommend a vena cava filter for people who cannot take anticoagulant medications and are at high risk for PE. The vena cava filter is a cone-shaped device. The surgeon implants this filter into the person's inferior vena cava, which is a large vein. The device filters blood clots and prevents them from entering the lungs, which reduces the risk of developing PE.

Thrombolytic therapy

Thrombolytic therapy may be necessary if a person has a very large blood clot or anticoagulant drugs do not work effectively. This type of therapy involves taking medications to dissolve the clot or surgery to remove it. Doctors usually recommend only thrombolytic therapy for severe thrombosis. In most cases, they will first conduct a thorough examination of the person to ensure that it is safe for them to undergo this type of therapy. Scientists say new anticoagulants may help prevent recurrent blood clots.

Compression stockings

Compression stockings can help improve circulation in your legs.

Doctors typically recommend compression stockings only for people who have an increased risk of popliteal vein thrombosis.

These stockings may also help with post-thrombotic syndrome. Possible symptoms include:

• pain and swelling;
• heaviness in the legs;
• convulsions.

Ultrasound diagnosis of venous thrombosis in an outpatient setting

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Introduction

Acute venous thrombosis is a common and dangerous disease. According to statistics, its frequency in the general population is about 160 per 100,000 population [1]. Thrombosis in the inferior vena cava (IVC) system is the most common and dangerous type of this pathological process and is the main source of pulmonary embolism (84.5%). The superior vena cava system accounts for 0.4-0.7% of pulmonary embolisms (PE), the right side of the heart - 10.4%. Thrombosis of the veins of the lower extremities accounts for up to 95% of cases of all thrombosis in the IVC system. Acute venous thrombosis is diagnosed intravitally in 19.2% of patients [2]. In the long term, deep vein thrombosis (DVT) leads to the formation of postthrombophlebitic disease, manifested by chronic venous insufficiency up to the development of trophic ulcers, which significantly reduces the ability to work and the quality of life of patients.

The main mechanisms of intravascular thrombus formation, known since the time of R. Virchow, are slowing of blood flow (stasis), hypercoagulation, injury to the vessel wall (endothelial damage). Acute venous thrombosis quite often develops against the background of various oncological diseases (malignant tumors of the gastrointestinal tract, female genital area, etc.) due to the fact that cancer intoxication causes the development of hypercoagulable changes and inhibition of fibrinolysis, as well as due to mechanical compression of the veins by the tumor and germination it into the vascular wall. Predisposing factors for DVT are also considered obesity, pregnancy, taking oral hormonal contraceptives, hereditary thrombophilias (deficiency of antithrombin III, protein C and S, Leiden mutation, etc.), systemic connective tissue diseases, chronic purulent infections, allergic reactions [3, 4]. Elderly and senile patients and persons suffering from chronic venous insufficiency of the lower extremities, as well as patients with myocardial infarction, decompensated heart failure, stroke, bedsores, and gangrene of the lower extremities are at the greatest risk of developing DVT. Trauma patients are of particular concern, since femoral fractures are mainly found in elderly and senile people, most burdened by somatic diseases [5]. Thrombosis in trauma patients can occur with any injury to the lower extremities, since all etiological factors of thrombosis (vascular damage, venous stagnation and changes in blood coagulation properties) take place [6].

Reliable diagnosis of phlebothrombosis is one of the current clinical problems. Physical examination methods make it possible to make a correct diagnosis only in typical cases of the disease, and the frequency of diagnostic errors reaches 50% [7]. For example, thrombosis of the veins of the calf muscles with preserved patency of the remaining veins is often asymptomatic. Because of the risk of missing acute DVT of the legs, clinicians often make this diagnosis in every case of pain in the calf muscles [8]. Particular attention should be paid to “trauma” patients, in whom the presence of pain, swelling and discoloration of the limb may be a consequence of the injury itself, and not of DVT. Sometimes the first and only manifestation of such thrombosis is massive pulmonary embolism.

The tasks of instrumental examination include not only confirming or refuting the presence of a thrombus, but also determining its extent and degree of embologenicity. Isolating embolic-dangerous thrombi into a separate group and studying their morphological structure are of great practical importance, since without this it is impossible to develop effective prevention of pulmonary embolism and select optimal treatment tactics. Thromboembolic complications are more often observed in the presence of a floating thrombus with a heterogeneous structure and an uneven hypo- or isoechoic contour, in contrast to thrombi that have a hyperechoic contour and a homogeneous structure. An important criterion for the embologenicity of a thrombus is the degree of its mobility in the lumen of the vessel. Embolic complications are more often observed with severe and moderate mobility of thrombomass [9, 10].

Venous thrombosis is a fairly dynamic process. Over time, the processes of retraction, humoral and cellular lysis help reduce the size of the thrombus. At the same time, processes of its organization and recanalization are underway. In most cases, vascular patency is gradually restored, the valve apparatus of the veins is destroyed, and the remains of blood clots in the form of wall overlays deform the vascular wall. Difficulties in diagnosis may arise when repeated acute thrombosis occurs against the background of partially recanalized veins in patients with postthrombophlebitic disease. In this case, a fairly reliable criterion is the difference in vein diameter: in patients with signs of recanalization of thrombus masses, the vein diameter decreases due to the subsidence of the acute process; with the development of rethrombosis, there is again a significant increase in the diameter of the vein with unclear (“blurred”) contours of the walls and surrounding tissues [9]. The same criteria are used in the differential diagnosis of acute parietal thrombosis with postthrombotic changes in the veins.

Of all the non-invasive methods used to diagnose thrombosis, ultrasound scanning of the venous system has recently been increasingly used. The triplex angioscanning method, proposed by Barber in 1974, includes the study of vessels in B-mode, analysis of the Doppler frequency shift in the form of classical spectral analysis and color flow mapping (in speed and energy modes). The use of spectral Doppler ultrasound made it possible to accurately measure blood flow within the lumen of the veins. The use of color Doppler mapping (CDC) made it possible to quickly distinguish occlusive from non-occlusive thrombosis, identify the initial stages of recanalization of thrombi, and also determine the location and size of venous collaterals. In dynamic studies, the ultrasound method allows for fairly accurate monitoring of the effectiveness of thrombolytic therapy. In addition, with the help of ultrasound, it is possible to determine the causes of clinical symptoms similar to those in venous pathology, for example, to identify a Baker's cyst, intermuscular hematoma or tumor. The introduction into practice of expert-class ultrasonic devices with sensors with frequencies from 2.5 to 14 MHz made it possible to achieve almost 99% diagnostic accuracy.

Material and methods

The examination included examination of patients with clinical signs of venous thrombosis and pulmonary embolism. Patients complained of swelling and pain in the lower (upper) limb, pain in the calf muscle (usually of a bursting nature), “pulling” pain in the popliteal region, pain and compaction along the saphenous veins. On examination, moderate cyanosis of the leg and foot, dense swelling, pain on palpation of the leg muscles were revealed; in most patients, positive Homans and Moses symptoms.

All subjects underwent triplex scanning of the venous system using modern ultrasound machines with a linear sensor with a frequency of 7 MHz. At the same time, the condition of the veins of the thigh, popliteal vein, veins of the leg, as well as the great and small saphenous veins was assessed. A 3.5 MHz convex probe was used to visualize the iliac veins and IVC. When scanning the IVC, iliac vein, great saphenous vein, femoral veins and veins of the leg in the distal lower extremities, the patient was in the supine position. The study of the popliteal veins, veins of the upper third of the leg and the small saphenous vein was carried out with the patient lying on his stomach with a cushion placed under the ankle joints. Difficulties in diagnosis arose when visualizing the distal part of the superficial femoral vein in obese patients, visualizing the veins of the leg with pronounced trophic and indural changes in tissue. In these cases, a convex sensor was also used. Scanning depth, echo signal amplification and other study parameters were selected individually for each patient and remained unchanged during the entire examination, including observations over time.

The scan was started in cross-section to exclude the presence of a floating tip of the thrombus, as evidenced by complete contact of the venous walls during light compression with the sensor. After making sure that there was no freely floating tip of the thrombus, a compression test with a sensor was carried out from segment to segment, from proximal to distal sections. The proposed method is the most accurate not only for detecting thrombosis, but also for determining its extent (excluding the iliac veins and IVC, where the patency of the veins was determined in the CD mode). Longitudinal scanning of the veins confirmed the presence and characteristics of venous thrombosis. In addition, longitudinal sectioning was used to locate the anatomical venous confluence. During the examination, the condition of the walls, the lumen of the veins, the localization of the thrombus, its extent, and the degree of fixation to the vascular wall were assessed.

Ultrasonic characterization of venous thrombi was carried out in relation to the lumen of the vessel: they were distinguished as parietal, occlusive and floating thrombi. Signs of parietal thrombosis were considered to be visualization of a thrombus with the presence of free blood flow in the lumen of the vein, the absence of complete collapse of the walls when the vein is compressed by a sensor, the presence of a filling defect during color circulation, and the presence of spontaneous blood flow during spectral Dopplerography (Fig. 1).

Rice. 1.

Non-occlusive thrombosis of the popliteal vein. Longitudinal scanning of the vein. Envelope blood flow in energy flow coding mode.

Ultrasound criteria for floating thrombi were: 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 apex of the thrombus, absence of contact of the vein walls during compression with the sensor, presence of free space when performing respiratory tests, circumflex type of blood flow during color circulation, the presence of spontaneous blood flow with spectral Doppler ultrasound. When a floating thrombus was detected, the degree of its mobility was assessed: pronounced - in the presence of spontaneous movements of the thrombus during quiet breathing and/or breath-holding; moderate - when oscillatory movements of a blood clot are detected during functional tests (cough test); insignificant - with minimal thrombus mobility in response to functional tests.

Research results

From 2003 to 2006, 236 patients aged from 20 to 78 years were examined, 214 of them with acute thrombosis and 22 with pulmonary embolism.

In the first group, in 82 (38.3%) cases, the patency of the deep and superficial veins was not impaired and clinical symptoms were due to other reasons (Table 1).

Table 1

. Conditions with symptoms similar to DVT.

The diagnosis of thrombosis was confirmed in 132 (61.7%) patients, while in most cases (94%) thrombosis was detected in the IVC system. DVT was detected in 47% of cases, superficial veins - in 39%, damage to both the deep and superficial venous systems was observed in 14%, including 5 patients with involvement of perforating veins.

The probable causes (risk factors) of the development of venous thrombosis are presented in table. 2.

table 2

. Risk factors for thrombosis.

In our observations, the most common form of thrombosis was detected, as well as damage to the veins at the level of the popliteal-tibial and femoral-popliteal segments (Table 3).

Table 3

. Localization of DVT.

More often (63%) there were thromboses that completely occluded the lumen of the vessel; in second place in frequency (30.2%) were mural thrombi. Floating thrombi were diagnosed in 6.8% of cases: in 1 patient - in the saphenofemoral anastomosis with ascending thrombosis of the trunk of the great saphenous vein, in 1 - ileofemoral thrombosis with a floating apex in the common iliac vein, in 5 - in the common femoral vein with thrombosis of the femoral-popliteal vein segment and in 2 - in the popliteal vein with DVT of the leg.

The length of the non-fixed (floating) part of the thrombus, according to ultrasound data, varied from 2 to 8 cm. Moderate mobility of thrombotic masses was more often detected (5 patients), in 3 cases the mobility of the thrombus was minimal. In 1 patient, during quiet breathing, spontaneous movements of the thrombus in the lumen of the vessel were visualized (high degree of mobility). In our observations, floating thrombi with a heterogeneous echostructure were more often detected (7 people), with the hyperechoic component predominant in the distal section, and the hypoechoic component in the area of ​​the thrombus head (Fig. 2).

Rice. 2.

Floating thrombus in the common femoral vein. B-mode, longitudinal scanning of the vein. Thrombus of a heteroechoic structure with a clear hyperechoic contour.

In the first case, an isoechoic thrombus with a hyperechoic contour was recorded (Fig. 3), in the second - a homogeneous “organized” thrombus with a clear contour (Fig. 4).

Rice. 3.

Floating thrombus in the superficial femoral vein. B-mode, longitudinal scanning of the vein. Thrombus of an isoechoic structure with a hyperechoic contour.

Rice. 4.

Floating thrombus in the superficial femoral vein. B-mode, longitudinal scanning of the vein. Thrombus of homogeneous echostructure with a clear contour.

In the group of patients with clinical pulmonary embolism, 5 (22.7%) patients had DVT of various stages of development (mainly the femoropopliteal segment).

Over time, 82 patients were examined to assess the course of the thrombotic process, of which 63 (76.8%) had partial recanalization of thrombotic masses. In this group, 28 (44.4%) patients had a central type of recanalization (with longitudinal and transverse scanning in the color flow mode, the recanalization channel was visualized in the center of the vessel); in 23 (35%) patients, parietal recanalization of thrombotic masses was diagnosed (most often, blood flow was determined along the wall of the vein directly adjacent to the artery of the same name); In 13 (20.6%) patients, incomplete recanalization was detected with fragmentary asymmetric staining in the Color Doppler mode. Thrombotic occlusion of the vein lumen was observed in 5 (6.1%) patients; in 6 (7.3%) cases, restoration of the vein lumen was noted. Signs of rethrombosis persisted in 8 (9.8%) patients.

conclusions

A comprehensive ultrasound examination, including angioscanning using spectral, color and power Doppler modes and echography of soft tissues, is a highly informative and safe method that allows the most reliable and quick solution to issues of differential diagnosis and treatment tactics in outpatient phlebological practice. It is advisable to conduct this study on an outpatient basis for earlier identification of patients for whom thrombolytic therapy is not indicated (and sometimes contraindicated), and to refer them to specialized departments; when confirming the presence of venous thrombosis, it is necessary to identify individuals at high risk of developing thromboembolic complications; monitor the dynamics of the thrombotic process and thereby adjust treatment tactics.

Literature

1. Lindblad, Sternby NH, Bergqvist D. Incidence of venous thromboembolism verified by necropsy over 30 years. //Br.Med.J. 1991. V. 302. P. 709-711.
2. Savelyev V.S. Pulmonary embolism - classification, prognosis and surgical tactics. // Thoracic and cardiovascular surgery 1985. N°5. pp. 10-12.
3. Barkagan Z.S. Hemorrhagic diseases and syndromes. Ed. 2nd, revised and additional M.:Medicine 1988; 525 pp.
4. Bergqvist D. Postoperative thromboembolism. // New York 1983. P. 234.
5. Savelyev V.S. Phlebology. M.: Medicine 2001; 664 pp.
6. Kokhan E.P., Zavarina I.K. Selected lectures on angiology. M.: Nauka 2000. P. 210, 218.
7. Hull R., Hirsh J., Sackett DL et al. Combined use of leg scenning and impedance plethysmography in suspected venous thrombosis. An alternative to venography. // N.Engl.J.Med. 1977. N° 296. P. 1497-1500.
8. Savelyev V.S., Dumpe E.P., Yablokov E.G. Diseases of the main veins. M., 1972. S. 144-150.
9. Albitsky A.V., Bogachev V.Yu., Leontyev S.G. and others. Ultrasound duplex angioscanning in the diagnosis of rethrombosis of the deep veins of the lower extremities. // Kremlin Medicine 2006. N°1. pp. 60-67.
10. Kharchenko V.P., Zubarev A.R., Kotlyarov P.M. Ultrasound phlebology. M.: ZOA "Eniki". 176 p.

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Prevention

Doctors usually prescribe anticoagulant drugs to people at high risk of blood clots, those recovering from certain types of surgery, or those who have previously had VTE. People taking anticoagulant medications should take them as directed.

A person can also reduce their risk of VTE by:

• wearing compression stockings;
• maintaining a healthy weight or losing weight as needed;
• regular exercise;
• getting up and moving around every 1-2 hours where possible;
• changing body position or bending legs from time to time;
• consuming large amounts of water;
• avoiding crossing your legs for long periods of time;
• stopping for breaks or stretching and walking every hour or so if you are traveling by car, train, bus or plane;
• quitting smoking.