Table 1: Risk Factors for Venous Thromboembolism.
General
Age
Trauma
Surgery
Leg immobilization or paralysis
Central venous catheter (for intravenous administration) or
transvenous pacemaker
Confinement in hospital or nursing home
Prior superficial venous thrombosis
Varicose veins
Acquired Risk Factors
Malignancy
Myeloproliferative disorders, such as leukemia and polycythemia
vera
Heparin-induced thrombocytopenia (decrease in platelet
count due to heparin therapy)
Kidney defects
Disseminated intravascular coagulation (overstimulation of blood
clotting factors)
Oral contraceptive use and estrogen therapy
Lupus anticoagulant/anticardiolipin antibody (clotting disorder
found in 10-30% of people with lupus erythematosus)
Pregnancy and postpartum period (period after childbirth)
Paroxysmal nocturnal hemoglobinuria (episodic loss of
hemoglobin)
Anticancer drug use
Inflammatory bowel disease
Thromboangiitis obliterans, also called Buerger's disease
(inflammation and clotting in the lower extremities, mainly in
young men).
Behçet's syndrome (chronic inflammation of the blood vessels of
the eyes and mucous membranes, mostly affecting young men)
Familial Risk Factors
Antithrombin III deficiency (clotting disorder)
Protein C and protein S deficiency (clotting disorders)
Activated protein C resistance (coagulation disorder)
Dysfibrinogenemia (deficiency of fibrinogen, a clotting factor, in
the blood)
Hypoplasminogenemia (deficiency of plasminogen, a clotting
factor, in the blood)
Hyperhomocysteinemia (an excess of the amino acid
homocysteine)
-------------------------------------------------------------------------
Modified from Gloviczki P, Yao, JST, eds. Handbook of Venous
Disorders,2nd ed. London: Arnold, 2001:226, Table 23.1 |
Venous thrombo-embolism is the overall term for a blood clot in a vein. These vein blood clots most commonly occur in the inner (deep) veins of the leg or pelvis (deep vein thrombosis). Because veins are carrying blood back to the heart from where it is pumped to the lungs, a deep vein thrombosis may dislodge from the leg veins, travel with the flowing blood back to the heart, and subsequently lodge in an artery to the lungs (as in pulmonary embolism). A pulmonary embolism may be fatal because blood cannot properly be resupplied with needed oxygen. Venous thromboembolism is a major health problem, with at least 201,000 new cases per year in the United States. One-fourth of affected patients die within 7 days of onset.
Whites and African-Americans have a higher incidence of venous thromboembolism; Hispanic-Americans are next and Asian-Americans are lowest. (Incidence is unknown among Native Americans.) Table 1 lists the major risk factors.
People who have had recent surgery have 22 times the risk for venous thromboembolism (Table 2).
Table 2. Percentage of Deep Venous Thrombosis (DVT) with No Prophylaxis, According to type of Surgery
| Type of Surgery |
Prevalence of DVT |
| General surgery |
19% |
| Abdominal/pelvic surgery for malignant disease |
29% |
| Total hip replacement |
51% |
| Total knee replacement |
61% |
| Hip fracture surgery |
48% |
| Neurosurgery |
24% |
| Surgery for multiple trauma |
53% |
Modified from Gloviczki P, Yao, JST, eds. Handbook of Venous Disorders, 2nd ed. London: Arnold, 2001:226, Table 23.2 |
|
