Deep vein thrombosis overview
Editor(s)-In-Chief: The APEX Trial Investigators, C. Michael Gibson, M.S., M.D. [1]; Associate Editor(s)-In-Chief: Cafer Zorkun, M.D., Ph.D. [2] ;Kashish Goel, M.D.; Assistant Editor(s)-In-Chief: Justine Cadet
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Overview
Deep vein thrombosis (also known as deep venous thrombosis or DVT and colloquially referred to as economy class syndrome) is the formation of a blood clot ("thrombus") in a deep vein. The risk is significantly increased if the thrombus embolizes to the lungs, causing pulmonary embolism. Occasionally, veins in the arm are also affected (known as Paget-Schrötter disease). Upper extremity DVT is less common but also may lead to PE, especially in the presence of a venous catheter.[1] Thrombophlebitis is swelling (inflammation) of a vein caused by a blood clot.
Classification
Deep vein thrombosis (DVT) is classified based on the site of occlusion or clot formation. Symptom presentation and complication is largely influenced by location of the embolus.
Pathophysiology
Venous thrombosis is composed of three mechanisms, collectively described as the Virchow's triad: 1. Alterations in blood flow (stasis): Venous stasis is a major risk factor for the development of thrombosis. It occurs in certain pathological conditions (as in heart failure) wherein it causes an increase in platelet to endothelium contact and decreases the dilution of clotting factors. This increases the risk of clot formation, and it forms microthrombi, which further grow and propagate. 2. Injury to the vascular endothelium (Endothelial dysfunction): Intrinsic or secondary to external trauma, such as catheterization, can cause intimal damage and stimulate clot formation. 3. Alterations in the constitution of blood (Hypercoagulability): Abnormal changes in coagulation can increase the propensity to develop thrombosis.
Differentiating Deep Vein Thrombosis from Other Diseases
Only 25% of the patient evaluated for deep vein thrombosis (DVT) have the disease.[2] DVT is characterized by pain and swelling of the limb, which is not specific. Numerous patients with DVT are asymptomatic.
Epidemiology and Demographics
In the United States, approximately 350,000 to 600,000 new cases of venous thromboembolism are diagnosed each year. The incidence of deep vein thrombosis is estimated to be 100 cases per 100,000 persons per year. Deep vein thrombosis accounts for two-thirds of all venous thromboembolism cases. Mortality and complications from deep vein thrombosis are high: one-third of the patients develop post-thrombotic syndrome and another 30% have recurrent DVT within 10 years. In the United States, deep vein thrombosis accounts for approximately 100,000 deaths each year.
Risk Factors
The identification and minimization of risk factors is important in the management of DVT. The duration of anticoagulation is guided by the presence of thrombophilic risk factors.
Natural History
Thrombus formation typically begins in the calf veins and naturally progresses to the proximal veins and ultimately, breaks free from the site formation and travels to the pulmonary artery where it is called a pulmonary embolism. In many cases, patients with a thrombus can be asymptomatic until it progresses into the proximal veins.
Diagnosis
Pretest Probability
In a patient with suspected DVT, establishing pre-test probability helps in early risk stratification and appropriate use of laboratory tests and imaging modalities. Many pretest probability scoring systems are proposed for use in primary care patients, like the Wells score, Hamilton score , and AMUSE score. [3][4] When combined with pretest probability, ultrasonography and D-dimer tests are most useful in a diagnosis for DVT.
History and Symptoms
A proper history and physical exam is very important for establishing an accurate diagnosis of DVT or VTE. One of the first steps in the management of DVT is the determination of the Wells score for DVT. Out of the 10 clinical questions in the score, 9 can be ascertained solely on the basis of history and physical exam. This underscores the importance of these variables. A high index of suspicion is also necessary to diagnose DVT.
References
- ↑ Ramzi DW, Leeper KV (2004). "DVT and pulmonary embolism: Part I. Diagnosis". Am Fam Physician. 69 (12): 2829–36. PMID 15222648.
- ↑ Huisman MV, Büller HR, ten Cate JW, Vreeken J (1986). "Serial impedance plethysmography for suspected deep venous thrombosis in outpatients. The Amsterdam General Practitioner Study". N Engl J Med. 314 (13): 823–8. doi:10.1056/NEJM198603273141305. PMID 3951515.
- ↑ Subramaniam RM, Chou T, Heath R, Allen R (2006). "Importance of pretest probability score and D-dimer assay before sonography for lower limb deep venous thrombosis". AJR Am J Roentgenol. 186 (1): 206–12. doi:10.2214/AJR.04.1398. PMID 16357403. Retrieved 2011-12-22. Unknown parameter
|month=ignored (help) - ↑ van der Velde EF, Toll DB, Ten Cate-Hoek AJ, Oudega R, Stoffers HE, Bossuyt PM, Büller HR, Prins MH, Hoes AW, Moons KG, van Weert HC (2011). "Comparing the diagnostic performance of 2 clinical decision rules to rule out deep vein thrombosis in primary care patients". Ann Fam Med. 9 (1): 31–6. doi:10.1370/afm.1198. PMC 3022042. PMID 21242558. Retrieved 2011-12-22.