Deep vein thrombosis (DVT) is a medical condition characterized by the formation of blood clots in the deep veins of the lower legs. This leads to leg swelling, pain, redness, and warmth. This disease typically affects people with risk factors such as prolonged immobility and cancer but can occur in any individual in any state of health.
Blood clots in the lower legs carry the risk of dislodging and traveling to the lungs – causing a life-threatening condition called pulmonary embolism.
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 generally only occurs in individuals requiring long-term intravenous antibiotics or chemotherapy that are given through lines that are placed in the arm or chest. The intravenous lines irritate the veins, resulting in inflammation and an increased risk of 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)
Most commonly, a deep vein thrombosis will occur due to a combination of these factors. Some patients are at increased risk of deep vein thrombosis due to their genetics, even if they don’t have any known genetic defects or a history of the above conditions.
Prolonged immobility is most common with 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 clots from forming.
Prolonged immobility may also occur in the elderly, patients with severe joint pain and arthritis, or hospitalization following surgery especially any surgery on the lower limbs.
Deep vein thrombosis is relatively common with approximately 0.1% of the population experiencing a deep vein thrombosis in any one year. In reality, this number is likely higher as some individuals only experience a very small deep vein thrombosis that does not lead to significant symptoms.
The majority of individuals with deep vein thrombosis are those that are hospitalized following an injury, the elderly, and those with pre-existing conditions that lead to blood clots. The risk of deep vein thrombosis among these populations is much higher.
Patients with deep vein thrombosis may have no symptoms or severe symptoms. Generally the symptoms develop over the course of several days following a long period of immobility, hospitilization, or a recent surgery. The most common symptoms of deep vein thrombosis include:
- Leg swelling
- Leg pain
- Redness & warmth of the leg
- Low grade fever
The most common and feared complication of a deep vein thrombosis is a pulmonary embolism. A pulmonary embolism results from the blood clot in the leg breaking off, traveling all the way to the heart, and then getting stuck in the lungs. This results in far more severe symptoms including:
- Chest pain that is worse with breathing (pleuritic pain)
- Difficulty breathing
- Coughing up 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 your history of symptoms, a physical examination, and confirmed with imaging that can visualize the veins of the leg.
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 ordered if ultrasound results are unreliable. A CT scan will also be ordered if your physician suspects a pulmonary embolism.
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 systemic lupus erythematosus may be leading to your blood clots they will typically order an antinuclear antibody (ANA) and anti-double-stranded DNA antibody (anti-DS DNA).
If the blood clot occured suddenly and there are no clear risk factors in your history, 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 critical as thee cancers are common and can result in hormone imbalances that lead to blood clots.
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 ECG (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 CT angiography– a CT scan that evaluates for any obstructions in the blood flow to the lungs.
The treatment of deep vein thrombosis is focused around blood thinners. These medications prevent the blood clot from growing larger and reduce the risk of it breaking off and obstructing the lungs. Over time this blood clot will naturally shrink and be absorbed by the body while on these medications.
Individuals who are at high risk for falls and head injury should generally avoid use of blood thinners. 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 filter placement is usually prefomed in patients who have conditions that make taking blood thinners risky.
If you and your doctor determine the benefits of oral anticoagulation outweigh its risks they may prescribe an oral blood thinner called Coumadin (warfarin). That reduces the ability of your blood to clot.
Warfarin interacts with a host of medications and foods (e.g., spinach, grapefruit, aspirin, tylenol, laxatives, cold/flu medication, and most antacids). This medication also needs to be monitored very closely with regular blood tests – therefore, a lot of patients are started on newer oral anticoagulants with fewer interactions such as:
- Xarelto (rivaroxaban)
- Eliquis (apixaban)
- Pradaxa (dabigatran)
- Wilbur J, Shian B. Deep Venous Thrombosis and Pulmonary Embolism: Current Therapy. Am Fam Physician. 2017 Mar 1;95(5):295-302. – https://www.aafp.org/afp/2017/0301/p295.html
- Kesieme E, Kesieme C, Jebbin N. Deep vein thrombosis: a clinical review. J Blood Med. 2011;2:59-69. – https://www.ncbi.nlm.nih.gov/pubmed/22287864