Deep venous thrombosis (DVT) is a common medical syndrome that affects 600,000 individuals per year. It is associated with blood clots that form in the extremities. Although it is most often found in the legs, DVT can also occur in the upper extremities, especially in hospitalized patients with indwelling central venous catheters.

In itself, DVT is often asymptomatic. However, pulmonary embolism is a feared complication of DVT, and one of the leading preventible causes of death in hospitals. Pulmonary embolism occurs when a blood clot travels from the extremity, through the bloodstream, and to the lung. Once there, the clot can choke off the blood supply to the lung and may result in life-threatening lung and heart diseases.

Symptoms

• Although most cases of DVT are asymptomatic, some patients may experience swelling, tenderness, warmth, and redness of the affected limb.
• Symptoms of pulmonary embolism may include shortness of breath, sharp chest pain, and coughing up blood.

Risk Factors

• Prior DVT or pulmonary embolism: These are the strongest indicators of risk.
• Age: Risk increases with age. This is due in part to the greater likelihood of comorbid illness as one gets older.
• Surgery: Major procedures (e.g., orthopedic, thoracic, abdominal, and genitourinary) pose the greatest risk.
• Trauma: Examples include fracture of the spine, pelvis, femur, or tibia.
• Disorders of blood clotting: These include protein C and S deficiencies, antithrombin III deficiency, and factor V Leiden.
• Prolonged immobilization: Examples include extended air travel, post-surgery, inability to walk (e.g., bedridden patients).
• Oral contraceptives and hormone replacement therapy: Oral contraceptive use is especially dangerous in women older than 35 years who are smokers.
• Additional risk factors include pregnancy, obesity, elevated cholesterol levels, and cancer.

Deep Venous Thrombosis: Diagnosis and Treatment

Diagnosis

• The first step is taking the patient's history and performing a physical examination.
• Blood testing may be used.
• The most commonly used imaging test for DVT is an ultrasound of the extremities. It is quick, inexpensive, noninvasive, and reasonably accurate.
  
  Further tests can be used to increase accuracy. The include magnetic resonance imaging (MRI) of the extremity, plethysmography, or venography. 
• If pulmonary embolism is suspected, further testing is necessary.
  
  Electrocardiogram (EKG) and chest X-ray are usually the first tests ordered, but they are not as accurate as CT scan of the chest, MRI of the chest, or ventilation-perfusion scan.

Treatment

• Patients with DVT are treated with anticoagulation medications (e.g., heparin, warfarin) to reduce the tendency of the blood to clot. Uncomplicated cases are generally treated for three to six months. Patients at higher risk are treated longer, perhaps even for life.
  
  In patients who cannot use anticoagulation therapy (e.g., those with active bleeding or a history of gastrointestinal bleeding), external compression devices can be used.
• Surgery may be necessary in some cases, particularly for high-risk patients, those who cannot take anticoagulation medications, or those who do not respond appropriately to anticoagulation medications.

Deep Venous Thrombosis: Nutritional Considerations

Several decades ago, it became clear that DVT was rare in societies whose diets were primarily based on unrefined plant foods, rather than animal products or highly refined foods, and, as a result, were lower in fat and higher in dietary fiber. However, the reasons for this association are still unclear.

In population studies, the following nutritional factors are associated with preventing DVT:

• Lipid-lowering diet: High cholesterol levels are associated with DVT risk. Some evidence suggests that simultaneously elevated cholesterol and triglycerides increase this risk.
  
  Greatly reducing dietary cholesterol and saturated fat and increasing dietary fiber have a major effect on blood cholesterol. As explained here, low-fat vegetarian diets are particularly effective.
• Weight control: Obesity is known to increase the risk for developing DVT. Here are some tips for controlling weight.
• Consistency of vitamin K intake for patients using warfarin anticoagulation: Even small increases in dietary vitamin K may interfere with the effectiveness of warfarin therapy. Conversely, decreased vitamin K intake may increase the risk of bleeding in patients using warfarin.
  
  Food sources of vitamin K (mainly green vegetables) need not be eliminated. However, vegetable intake should be consistent from day to day to avoid excessively low or high intakes. Further, patients should not take a vitamin K supplement without physician approval.