Deep vein thrombosis (DVT)

Definitions:

It’s a blood clot that happens most commonly in the calf veins, but it can also occur in popliteal, femoral, or iliac veins.

Epidemiology:

In a study done in US, they found that the Annual incidence rates per 1000 at age 65 to 69 years for DVT was 1.8, and it increases with age to 3.1 by age 85 to 89 years.
The incidence of venous thromboembolism exceeds 1 per 1000; over 200,000 new cases occur in the United States annually. Of these, 30% died within 30 days; one-fifth suffer sudden death due to pulmonary embolism.

Pathophysiology:

Virchow’s triad suggests that there are three components that are important in thrombus formation:

1- Slowing down the blood flow: changes in the circulatory states due to stenosis, atrial fibrillation, or immobilization person can enhance the formation of thrombus.

2- Hypercoagulability of the blood: people with the state of increase platelet or coagulation factors due to high vitamin K intake, drug induce hypercoagulability, or some cancers have high chance to form thrombus.

3- Vessel wall damage: Collagen underline the endothelium activates the coagulation cascade and form thrombus. Vitamin C deficiency and vasculitis considered as factors that damages the endothelium and exposed underlying the collagen.

Risk factors:

Risk factors for venous thrombosis are divided to hereditary and acquired.

1- Hereditary hemostatic disorders:

Factor V Leiden
Prothrombin G20210A variant
Protein C deficiency
Antithrombin deficiency
Protein S deficiency
Dysfibrinogenemia

2- Acquired risk factors:

Lupus Anticoagulant.
Oral contraceptive and hormone replacement thereby.
Pregnancy and puerperium
Surgery
Major trauma
Malignancy
Acutely ill hospitalized patients
Age
Obesity
Hyperviscosity, polycythemia
Varicose veins with phlebitis
Patients who are at risk of bleeding

Signs and symptoms:

Pain in the calf
Calf tenderness
Decreased in the skin temperature
Ankle and calf edema
Superficial venous dilation (non-varicose)
Unilateral calf or thigh swelling
Homan’s sign (pain in the calf on flexing the ankle)

Diagnosis:

In addition to the signs and symptoms mentioned above, the following test and procedures can be done to confirm the diagnosis.

1- Serial comparison ultrasound: a reliable and practical test for patients with the first suspicion of DVT in the legs or other sites.

2- Contrast venography: the most sensitive procedure is reserved for a patient with highly suggestive clinical finding but negative ultrasonography. However, it’s a painful procedure with a risk of contrast reaction and procedure-induces DVT.

3- Plasma d-dimer concentration: the concentration of fibrin breakdown products is raised at early thrombosis. It’s useful with a combination of the clinical probability in Wells’ Score. DVT can be excluded at the emergency department when it’s negative. However, it is not a specific test because it can be elevated in many other conditions.

4- Magnetic resonance imaging (MRI): this may also be used but expensive.

5- Wells’ score: is used after taking history and physical examination. It evaluates DVT’s patients (see Figure 1)

Figure 1. Wells’ Score for DVT evaluation

Management:

In addition to the signs and symptoms mentioned above, the following test and procedures can be done to confirm the diagnosis.

• Anticoagulant treatment: the aim is to prevent further thrombosis and pulmonary embolization while the resolution of venous thrombi occurs through natural fibrinolytic activity.

• LMW heparin is equally effective and safe as safe as unfractionated heparin in the immediate treatment of DVT.

• Length of anticoagulation: it’s recommended for at least 6 weeks after precipitated isolated calf vein thrombosis and at 3 months after precipitated proximal DVT in patients who have temporary risk factors.

• the role of thrombolytic therapy in the treatment of venous thrombosis is not established. it’s used in patients with extensive DVT. Thrombolytic therapy should be followed by anticoagulation with heparin for a few days and then by oral anticoagulant to prevent re-thrombosis.

References:

1- Kumar P, Clark M. Kumar & Clark's clinical medicine. 9th ed.

2- Hoffbrand A, Moss P. Hoffbrand's essential haematology. 6th ed.

3- Le T, Krause K, Eby E. First Aid for the Basic Sciences. 2nd ed. New York, USA: McGraw-Hill Professional Publishing; 2009.

4- Kniffin WD, Baron JA, Barrett J, Birkmeyer JD, Anderson FA. The epidemiology of diagnosed pulmonary embolism and deep venous thrombosis in the elderly. Archives of internal medicine. 1994 Apr 25;154(8):861-6.

5- Heit JA, Silverstein MD, Mohr DN, Petterson TM, Lohse CM, O’Fallon WM, Melton III LJ. The epidemiology of venous thromboembolism in the community. Thrombosis and haemostasis. 2001 Jul;86(01):452-63.

6- The wells score scale is taken from: https://ptreviewer.com/wells-score-dvt/

7- Figure 1 - https://dundeemedstudentnotes.wordpress.com/2014/05/08/deep-vein-thrombosis-and-pulmonary-embolism/

First author:

Abdulaziz Abdullah Aldabbas

Reviewed by:

Abdullah Al tamimi

Abdulrahman Alhassan

Format Editor:

Noura Abdullah Alsuabie

Study guide: