Pathophysiology of Deep Vein Thrombosis
1) deep vein thrombosis is formation of venous blood clot
2) classic triad predisposing to DVT – endothelial injury, stasis, and hypercoagulable state
3) after formation, the clot can undergo lysis, organization, propagation, or embolization
4) 90% occur in deep veins of the legs (usually in the sinuses above the venous valves in the calf veins)
5) also can occur in iliac and femoral veins
Signs and Symptoms
1) deep vein thrombosis can be asymptomatic if deep vein thrombosis is small or located in iliofemoral and pelvic system
2) calf tenderness on flexion of foot (Homans’ sign)
3) erythema over affected vein
4) increased circumference of calf or thigh
5) cyanosis distal to clot if large
6) if large, can result in chronic venous insufficiency with edema, hyperpigmentation, induration of the skin, and ulceration above the medial malleolus of the affected leg
Characteristic Test Findings
Radiology – best test for deep vein thrombosis is Doppler ultrasound
Associated Conditions
1) increased incidence of deep vein thrombosis in trauma, surgery, prolonged bed rest, oral contraceptives, advanced age, sickle cell anemia, pancreatic cancer, ulcerative colitis
2) increased incidence of pulmonary embolism
Treatment
1) the best treatment for deep vein thrombosis is prevention
2) in hospitalized patients this is early and aggressive ambulation
3) systemic anticoagulants
2) thombolytic therapy with tissue plasminogen activator (TPA) in selected cases
3) caval interruption if recurrent or if PE occurs through anticoagulation
Tips for USMLE
1) Homan’s sign is calf tenderness on foot flexion
2) if the question mentions unilateral calf or leg swelling, consider deep vein thrombosis
3) classic triad for deep vein thrombosis formation is endothelial injury, stasis, and hypercoagulable state
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