Deep Vein Thrombosis
Causes
The venous system of the lower extremity is divided into the superficial veins, which include the great and small saphenous veins and their associated accessory tributaries and the deep venous system, which includes the femoral and popliteal veins. Intermediate veins called perforators connect them. When a clot forms in the deep vein system it is called a deep vein thrombosis, or DVT.
DVTs usually occur in the lower extremities, but they can appear in other parts of the body.
A DVT can break off and travel to the lungs. The free-floating clot is called an embolus. This blocks blood flow, and the condition results in a pulmonary embolism, or PE.
A PE is a dangerous condition because it can damage the lungs and other organs and is life threatening.
Symptoms
- Tenderness, redness, warmth, and pain in the leg(s)
- Edema (swelling) of the legs(s)
Diagnosis
Evaluation and testing usually comprises a physical exam, which can demonstrate redness and swelling of the affected extremity. Associated diagnostics can include a D-dimer blood test, Doppler diagnostic ultrasound, plethysmography, or even venography (a specialized x-ray of the veins).
Risk Factors
This list is not all-inclusive, but some of the risks are detailed below.
1. Previous history of DVT
2. Pregnancy and the postpartum period
3. Obesity
4. Cigarette smoking
5. Long plane rides or car trips (usually longer than four hours)
6. Oral contraceptives/”birth control” pills
7. Hormone replacement therapy (synthetic and “natural”)
8. Active cancer
9. Age greater than 60
10. Family history of blood clots which may include genetic tendencies for:
a. Antithrombin III deficiency (a protein that tries to prevent clotting in the body)
b. Protein C or Protein S deficiency (additional proteins that prevent clotting that occurs in the body)
c. Factor V Leiden (a genetic mutation with increases tendency to develop clots)
d. Activated Protein C resistance (can be acquired as well as being hereditary)
e. Prothrombin 20210 mutation (additional mutation that increases tendency to develop clots)
11. Major surgery greater than 45 minutes in duration
12. Immobilization longer than 3 days
13. Ulcerative colitis/Crohn’s Disease (inflammatory bowel disease)/proctitis
14. Autoimmune disorders including systemic lupus erythematosus (SLE), antiphospholipid antibodies, and Behcet syndrome
15. A history of multiple miscarriages
16. Polycythemia vera (high hemoglobin level)
17. Thrombocytosis (elevated platelet count, the particles in the blood that actually clot)
18. Congestive heart failure
19. Recent stroke
20. Recent heart attack
21. Conditions that affect the kidney including nephrotic syndrome and homocystinuria
22. Major trauma and broken bones, especially fractures of the leg(s) and pelvis
23. Recent pacemaker insertion
24. Head injury
Treatment
The first treatment of choice, after confirming the diagnosis of DVT, is to initiate anticoagulation. This will keep more clots from forming or old ones from getting bigger. These drugs cannot dissolve existing clots. The goal of therapy is to stabilize the clot and prevent enlargement, reducing the risk of PE.
- A drug called warfarin (Coumadin) is usually started along with blood thinner known as enoxaparin or one of its equivalents.
- Enoxaparin is administered by an injection
- When you are taking blood thinners, you are more likely to bleed, even from activities you have always done.
- Warfarin is taken by mouth. It takes several days to fully work.
- Enoxaparin is not stopped until the warfarin has been at the right dose for at least 2 days.
- Most need to take warfarin at least 3 months. Others may need to take it for the rest of their lives, depending on their risk for another clot.
Studies have shown that a DVT can be treated safely as an outpatient by initiating enoxaparin and warfarin therapy. Some clinicians still prefer to admit patients to the hospital for initiation of blood thinning, given the potential for PE.
Use of prescription strength compression stockings for two years after a DVT has been shown to reduce the risk of chronic leg swelling (post-phlebitic syndrome).
If the patient is not a candidate for these blood thinners, an alternative is to utilize an inferior vena cava filter, and can be either temporary (removable) or permanent. Additional surgical treatment includes removal of a large blood clot from the vein or injection of a thrombolytic (clot-busting medicine).
Prevention
Move often! Stretching your legs often during long plane trips, car trips, and other situations in which you are sitting for extended periods.
Talk to your health care provider to discuss your risk for DVT, especially for flights longer than 4 hours or undergoing high-risk surgery.
Wear prescription strength compression stockings. By improving venous blood flow in your legs, well-fitted compression stockings can reduce your DVT risk.
Stop smoking and maintain a healthy body weight.
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