![]() Clinically, proximal vein thrombosis is of greater importance and is associated with serious chronic diseases such as active cancer, congestive cardiac failure, respiratory insufficiency, or age above 75 years, whereas distal thrombosis is more often associated with risk factors such as recent surgery and immobilization. 18ĭVT in the lower limb can be classified as a) proximal, when the popliteal vein or thigh veins are involved or b) distal, when the calf veins are involved. They almost always have a point of attachment to the wall and transection reveals vague strands of pale gray fibrin. This is in contrast to the venous thrombi which are firmer. They are usually not attached to the underlying wall. Postmortem clots are gelatinous and have a dark red dependent portion (formed by red cells that have settled by gravity and a yellow chicken fat supernatant resembling melted and clotted chicken fat). Venous thrombus must be differentiated from postmortem clot at autopsy. Thrombus is composed predominantly of fibrin and red cells (red or static thrombus). This means an upregulation of anticoagulants (EPCR, TM) and a downregulation of procoagulant (vWF) properties of the valvular sinus endothelium. Lending its support to the origin of thrombus in valve pockets is a recent hypothesis of an increased expression of endothelial protein C receptor (EPCR) and thrombomodulin (TM) and a decreased expression of Von Willebrand factor (vWF) noted in valve sinus endothelium compared with vein luminal endothelium. 16 Though most thrombi begin intraoperatively, some start a few days, weeks, or months after surgery. This is especially true for those that occur following surgery. Thrombus formation preferentially starts in the valve pockets of the veins of the calf and extends proximally. 14 Though regarded mainly as a surgical complication, most symptomatic VTE events and fatal PE occur in medical patients. 13 Geerts et al revealed that without prophylaxis, fatal PE occurs in 0.2% to 0.9% of patients undergoing elective general surgery, 0.1% to 2% of those undergoing elective hip replacement and up to 2.5% to 7.5% of those undergoing surgery for hip fracture. It nearly doubles after hip or knee replacement surgery or hip fracture surgery (40% to 60%). The approximate risk for DVT following general surgery procedures is 15% to 40%. 11 The incidence appears to be highest in the postpartum period. 10 In a study conducted in an African population, the documented rate was 48 DVT per 100,000 births per year. Pregnant women have a much higher risk of VTE than nonpregnant women of similar age and the risk has been shown to be higher after cesarian section than after vaginal delivery. 8 The incidence rate is comparatively higher in adolescent females because of pregnancy and use of oral contraceptive agents. The highest incidence in childhood is during the neonatal period, followed by another peak in adolescence. 6, 7 This low incidence may be due to decreased capacity to generate thrombin, increased capacity of alpha-2-macroglobulin to inhibit thrombin, and enhanced antithrombin potential of vessel walls. Annual incidences of 0.07 to 0.14 per 10,000 children and 5.3 per 10,000 hospital admissions have been reported in Caucasian studies. The risk of recurrence in Caucasians is lower than that of African-Americans and Hispanics. Hispanic patients’ risk is about half that of Caucasians. 2Ī study by Keenan and White revealed that African-American patients are the highest risk group for first-time VTE. 3, 4 DVT is predominantly a disease of the elderly with an incidence that rises markedly with age. ![]() ![]() 2 Both sexes are equally afflicted by a first VTE, men having a higher risk of recurrent thrombosis. The overall average age- and sex-adjusted annual incidence of venous thromboembolism (VTE) is 117 per 100,000 (DVT, 48 per 100,000 PE, 69 per 100,000), with higher age-adjusted rates among males than females (130 vs 110 per 100,000, respectively). It affects approximately 0.1% of persons per year. DVT is a major and a common preventable cause of death worldwide.
0 Comments
Leave a Reply. |
AuthorWrite something about yourself. No need to be fancy, just an overview. ArchivesCategories |