This is because lower limb SVTs can migrate from superficial veins into deeper veins. In a French population, the percent of people with SVTs that also suffered from PEs was 4.7%. In the same population, deep vein thrombosis (DVT) was found in 24.6% of people with SVTs. However, because superficial veins lack muscular support, any clots that form are far less likely to be squeezed by muscle contraction, dislodged, and induce a PE.SVTs can recur after they resolve, which is termed "migratory thrombophlebitis." Migratory thrombophlebitis is a complication that may be due to more serious disorders, such as cancer and other hypercoagulable states. Causes
SVTs of the legs are often due to varicose veins, though most people with varicose veins do not develop SVTs. SVTs of the arms are often due to the placement of intravenous catheters.Many of the risk factors that are associated with SVT are also associated with other thrombotic conditions (e.g. DVT). These risk factors include age, cancer, history of thromboembolism, pregnancy, use of oral contraceptive medications (containing estrogen), hormone replacement therapy, recent surgery, and certain autoimmune diseases (especially Behçets and Buergers diseases). Other risk factors include immobilization (stasis) and laparoscopy.Hypercoagulable states due to genetic conditions that increase the risk of clotting may contribute to the development of SVT, such as factor V Leiden, prothrombin 20210A mutation, and protein C, S, and antithrombin III and factor XII deficiency. Mechanism
The mechanism for the development of an SVT depends upon the specific etiology of the SVT.
Surgery
Surgical interventions are used for both symptomatic relief of the SVT as well as for preventing the development of more serious complications (e.g. pulmonary embolism). Surgical interventions include ligation of the saphenofemoral junction, ligation and stripping of the affected veins, and local thrombectomy. Because of the risk of symptomatic pulmonary embolism with surgery itself, surgical interventions are not recommended for the treatment of lower limb SVTs by the 2012 American College of Chest Physicians guidelines and the 2012 British Committee for Standards in Haematology guidelines. The use of surgery for the treatment of SVT is controversial. Prognosis
SVT is often a mild, self-resolving medical condition. The inflammatory reaction may last up to 2–3 weeks, with possible recanalization of the thrombosed vein occurring in 6–8 weeks. The superficial vein may continue to be hyperpigmented for several months following the initial event. Epidemiology
In a French population, SVT occurred in 0.64 per 1000 persons per year. History
SVTs have been historically considered to be benign diseases, for which treatment was limited to conservative measures. However, an increased awareness of the potential risks of SVTs developing into more serious complications has prompted more research into the diagnosis, classification, and treatment of SVTs. Research
A Cochrane review recommends that future research investigate the utility of oral, topical, and surgical treatments for preventing the progression of SVTs and the development of thromboembolic complications. Footnotes


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