1、 Deep vein thrombosis Xiang Yu Cheng What Is Deep Vein Thrombosis?The earliest case of DVT was described around 600-900 BC.At some point,the increased incidence of DVT in women after childbirth was noticed,and in the late 1700s,a public health recommendation was issued to encourage women to breast f
2、eed as a means to prevent this phenomenon;the DVT was called milk leg,as it was thought to result from milk building up in the leg.What Is Deep Vein Thrombosis?Deep vein thrombosis,or DVT,is a blood clot that forms in a vein deep in the body.Blood clots occur when blood thickens and clumps together.
3、What Is Deep Vein Thrombosis?A blood clot in a deep vein can break off and travel through the blood.The embolus could travel to an artery in the lungs and block blood flow.This condition is called pulmonary embolism,or PE.Epidemiology Deep vein thrombosis*Diagnoses of DVT and PE are not mutually exc
4、lusive;an estimated 78,511 patients received diagnoses of both DVT and PE.VTE estimates include patients with diagnoses of either DVT or PE.Epidemiology Deep vein thrombosis According to the most recent ACCP guidelines,VTE remains the second most common cause of protracted hospital stay and the thir
5、d most common cause of excess mortality among 7 million patients discharged from 944 acute care hospitals in the US.Causes German pathologist Rudolf Virchow postulated the interplay of three processes resulting in venous thrombosis,now known as Virchows triad:Deep vein thrombosis In keeping with Vir
6、chows concept,alterations of the coagulation system that induce a hypercoagulable state also confer an increased risk of DVT.Causes German pathologist Rudolf Virchow postulated the interplay of three processes resulting in venous thrombosis,now known as Virchows triad:Deep vein thrombosis Causes The
7、 blood flow pattern in the valves can cause hypoxemia,which is worsened by venous stasis,activates pathways-ones that include hypoxia-inducible factor-1and early-growth-response protein 1.Hypoxia-inducible factor-1 and early-growth-response protein 1 contribute to monocyte association with endotheli
8、al proteins,such as P-selectin,prompting monocytes to release tissue factor-filled microvesicles,which presumably begin clotting after binding to the endothelial surface.9 Deep vein thrombosis Causes Independent Risk Factors for DVT Age is an independent risk factor for thrombotic disease.The majori
9、ty of venous thrombi occur in either the superficial or deep veins of the leg.A DVT is stationary clotting blood adhered to the deep vein of the pelvis or an extremity and usually occurs in the calf or thigh.VTE denotes an obstruction arising from the formation of a clot in the venous circulation ca
10、rried by the blood from the site of origin to plug another vessel.Deep vein thrombosis Causes Independent Risk Factors for DVT Deep vein thrombosis Signs and symptoms Common signs and symptoms of DVT include：Pain Swelling Warmth Redness or discoloration Distention of surface veins Deep vein thrombos
11、is Signs and symptoms Common signs and symptoms of DVT include：Pain Swelling Warmth Redness or discoloration Distention of surface veins Deep vein thrombosis Signs and symptoms In most suspected cases,DVT is ruled out after evaluation,and symptoms are more often due to other causes,such as celluliti
12、s,Bakers cyst,musculoskeletal injury,or lymph edema.Other differential diagnoses include hematoma,tumors,venous or arterial aneurysms,and connective tissue disorders.Deep vein thrombosis Diagnosis Probability:In those with suspected DVT,a clinical assessment of probability can be useful to determine
13、 which tests to perform.The most studied clinical prediction rule is the Wells score.Deep vein thrombosis Diagnosis Deep vein thrombosis Diagnosis Physical Exam:symptoms Half of those with the condition HAVE NO SYMPTOMS.Signs and symptoms alone are not sufficiently sensitive or specific to make a di
14、agnosis,but when considered in conjunction with known risk factors can help determine the likelihood of DVT.Deep vein thrombosis Diagnosis DVT diagnosis requires the use of imaging devices such as ultrasound.Clinical assessments,which predict DVT likelihood,can help determine if a D-dimer test is us
15、eful.In those not highly likely to have DVT,a normal D-dimer result can rule out a diagnosis.Deep vein thrombosis Diagnosis D-dimer:A fibrin degradation product,and an elevated level can result from plasmin dissolving a clot,or other conditions.Deep vein thrombosis Diagnosis For those with a low or
16、moderate probability of DVT,a D-dimer level might be obtained,which excludes a diagnosis if results are normal.An elevated level requires further investigation with diagnostic imaging to confirm or exclude the diagnosis.Deep vein thrombosis Diagnosis For a suspected first leg DVT in a low-probability situation,the American College of Chest Physicians(ACCP)recommends testing either D-dimer levels with moderate or high sensitivity or compression ultrasound of the proximal veins.Deep vein thrombosi