Atlas of Pathos Chapter 6

Deep Vein Thrombosis

A n acute condition characterized by inflammation and thrombus formation, deep vein thrombosis (DVT) mainly refers to thrombosis in the deep veins of the legs. Without treatment, this disorder is typically progressive and can lead to potentially lethal pulmonary embolism. DVT commonly begins with localized inflammation alone (phlebitis), which rapidly provokes thrombus formation. Rarely, venous thrombosis develops without associated inflammation of the vein. Causes • Idiopathic • Endothelial damage

Signs and Symptoms • Vary with site and length of the affected vein (may produce no symptoms) • Pain or tenderness • Fever and chills • Malaise • Edema (unilateral edema is most common sign and may be only sign of DVT) • Redness and warmth over the affected area • Palpable vein • Surface veins more visible • Lymphadenitis

• Accelerated blood clotting • Reduced blood flow, stasis • Virchow’s triad

Clinical tip Some patients may display signs of inflammation.

Predisposing Risk Factors • Prolonged bed rest • Trauma, especially hip fracture • Surgery, especially hip, knee, or gynecologic surgery • Childbirth • Hormonal contraceptives such as estrogens • Age over 40

DiagnosticTest Results • Duplex Doppler ultrasonography reveals sluggish blood flow. • Impedance plethysmography shows a difference in blood pressure between the arms and the legs. • Impedance phlebography shows decreased blood flow. • Coagulation studies reveal an elevated prothrombin time in the presence of a hypercoagulable state. • Clotting factor deficiencies can be identified on blood work. • CT scan is more accurate in identifying presence of DVT. Treatment The goals of treatment are to control thrombus development, prevent complications, relieve pain, and prevent recurrence of the disorder. Treatment includes: • bed rest with elevation of the affected arm or leg • warm, moist soaks over the affected area • analgesics • antiembolism stockings • anticoagulants (initially, heparin; later, warfarin) — this is most important • streptokinase • simple ligation to vein plication, or clipping • embolectomy and insertion of a vena caval umbrella or filter.

• Obesity • Cancer Pathophysiology

A thrombus forms when an alteration in the epithelial lining causes platelet aggregation and consequent fibrin entrap- ment of red and white blood cells and additional platelets. Thrombus formation is more rapid in areas where blood flow is slower, because contact between platelets increases and throm- bin accumulates. The rapidly expanding thrombus initiates a chemical inflammatory process in the vessel epithelium, which leads to fibrosis (narrowing of the blood vessel). The enlarg- ing clot may occlude the vessel lumen partially or totally, or it may detach and embolize to lodge elsewhere in the systemic circulation.

Complications • Pulmonary embolism • Chronic venous insufficiency

62  Part II • Disorders