Deep Vein Thrombosis

What is Deep Vein Thrombosis?

Deep vein thrombosis (DVT) is a medical condition characterized by the formation of blood clots in the deep veins.  This most often occurs in one of the lower limbs causing leg swelling, pain, redness, and warmth.  This disease typically affects people with risk factors such as prolonged immobility and cancer.

Blood clots in the lower legs carry the risk of dislodging and traveling to the lungs - causing a life threating condition called pulmonary embolism. 

What Causes Deep Vein Thrombosis?

Deep vein thrombosis is caused by blot clot formation in the deep veins of the limbs.  This most frequently affects one of the lower limbs – although in some cases both legs are affected simultaneously.  The condition can also affect the upper limbs – which commonly occurs in individuals requiring long term intravenous antibiotics or chemotherapy through the arm or chest.  The intravenous lines irritate the veins, resulting in inflammation and an increased propensity for blood clot formation.

The most common risk factors for the development of deep vein thrombosis include:

  • Previous history of deep vein thrombosis or pulmonary embolism
  • Prolonged immobility
  • History of cancer
  • Genetic defect – prothrombin mutation, factor V – Leiden,
  • Other medical condition – systemic lupus erythematosus
  • Certain medications – oral contraceptives, estrogen/progesterone therapy
  • Long term intravenous line (e.g., PICC line, chemotherapy catheter)

Sometimes deep vein thrombosis occurs due to a combination of these factors.

Prolonged immobility can happen in situations such as prolonged flights or car rides.  It is usually recommended that individuals on flights take frequent breaks from sitting to prevent pooling of blood in the lower limbs and clot formation.  Massaging and stretching the legs can also be beneficial in preventing blood clot from forming.

Prolonged immobility may also occur in the elderly, patients with severe join pain and arthritis, individuals with para- or quadriplegia (e.g., spinal cord injury).  Any individual who is wheelchair dependent is at increased risk for deep vein thrombosis.

How Common is Deep Vein Thrombosis?

Deep vein thrombosis is a common condition that is frequently evaluated in the emergency department and primary care settings.  It is a major and common preventable cause of death worldwide.  It affects approximately 0.1% of people each year.  DVT is predominantly a disease of the elderly with an incidence that significantly increases with age.

Signs and Symptoms

The most common symptoms of deep vein thrombosis include:

  • Leg swelling
  • Leg pain
  • Redness & warmth of the leg
  • Low grade fever

If the blood clot in the leg gets dislodged and travels to the lungs – pulmonary embolism - you will typically experience sudden chest pain and difficulty breathing.  The pain can worsen on deep breathing or inspiration – a phenomenon called pleuritic chest pain.  You may also cough up specks of blood (hemoptysis).

Patients with pulmonary emboli typically have elevated heart rates (tachycardia) and low oxygen levels (hypoxia).  Large pulmonary emboli can cause heart failure and sudden death.


Deep vein thrombosis is diagnosed based on symptoms, physical examination, and confirmed with tests.

If you doctor suspects a deep vein thrombosis, they will usually obtain a duplex ultrasound of the deep vein of the leg or arms.  A CT scan is occasionally necessary if ultrasound results are equivocal.

Your doctor will also likely order blood tests such as a CMP (comprehensive metabolic panel), CBC (complete blood cell count), and coagulation studies (PT/INR, PTT).  If they think you could have systemic lupus erythematosus they will typically order an antinuclear antibody (ANA) and anti-double-stranded DNA antibody (anti-DS DNA).

Your doctor will also usually evaluate for genetic disorders that lead to blood clot formation.  These include:

  • Factor V Leiden
  • Anti-thrombin deficiency
  • Protein C and S deficiency
  • APC resistance
  • Prothrombin mutation

They may also perform age appropriate cancer screening.  This may include a prostate-specific antigen (PSA) for prostate cancer in men and a Papanicolaou (PAP) smear for cervical cancer in women.  Additional recommendations may include a colonoscopy if you have risk factors such as family history or age over 50 years.  Breast cancer screening in women is also an important consideration.

If your doctor suspects pulmonary embolism they will direct you to the nearing emergency department for further evaluation and hospitalization – this is a medical emergency.  In the hospital, they will order an EKG (electrocardiogram) and ultrasound of the heart (echocardiogram) to evaluate the heart’s function and structure.  One of the most commonly used studies to confirm a pulmonary embolism is called a CT angiography – a CT scan evaluating for interruptions of blood flow to the lungs.

Deep Vein Thrombosis Medication and Treatment

The treatment of deep vein thrombosis most always weigh the risks and benefits of treatment.  Individuals who are at high risk for falls and head injury should generally avoid use of blood thinner such as oral anticoagulants.  Patients with a history of serious gastrointestinal bleeding should also avoid taking these medications given the risk of re-bleeding.  Sometimes an interventional procedure is performed called inferior vena cava (IVC) filter placement.

The IVC (inferior vena cava) is the large vein that drains venous blood back from the lower part of your body to your heart.  IF you have a blood clot in the legs, this filter can prevent the blood clot from traveling to the lung – pulmonary embolism.  IVC placement is usually indicated in patients who have contraindications to oral anticoagulants.

If you and your doctor determine the benefits of oral anticoagulation outweigh its risks, they may prescribe an oral blood thinner called Coumadin (warfarin).

Warfarin interacts with a host of medications and foods (e.g., spinach).  This medication also needs to be monitored very closely with regular blood tests – therefore, a lot of patients are started on newer oral anticoagulants such as:


  1. Wilbur J, Shian B. Deep Venous Thrombosis and Pulmonary Embolism: Current Therapy. Am Fam Physician. 2017 Mar 1;95(5):295-302. -
  2. Kesieme E, Kesieme C, Jebbin N. Deep vein thrombosis: a clinical review. J Blood Med. 2011;2:59-69. -

The above information is an educational aid only. It is not intended as medical advice for individual conditions or treatments. Talk to your doctor, nurse or pharmacist before following any medical regimen to see if it is safe and effective for you.