Causes & symptoms - Phlebitis - Causes and Symptoms

The main symptoms of phlebitis are tenderness and pain in the area of the affected vein. Redness and/or swelling may also be seen. In the case of deep venous thrombosis, there is more swelling than is caused by superficial thrombophlebitis, and the patient may experience muscle stiffness in the affected area.

There are many causes of thrombophlebitis. The main causes can be grouped into three categories: injury to veins, increased blood clotting, and blood stasis. When blood veins are damaged, collagen in the vein wall is exposed. Platelets respond to collagen by initiating the clotting process. Damage to a vein can occur as a consequence of in-dwelling catheters, trauma, infection, Buerger's disease, or the injection of irritating substances. Increased tendency of the blood to clot can be caused by malignant tumors, genetic disorders, high-fat diets, and oral contraceptives. Stasis, in which the blood clots due to decreased blood flow in an area, can happen following surgery, as a consequence of varicose veins, as a complication of postpartum states, and following prolonged bed rest. In the case of prolonged bed rest, blood clots form because of inactivity, allowing blood to move sluggishly and stagnate (collect) in the veins. Stasis can lead to blood clots. These clots (also called emboli) are sometimes released when the patient stands up and resumes activity. Emboli can present a problem if they lodge in vital organs. In the case of postpartum patients, a fever developing four to 10 days after delivery may indicate thrombophlebitis. It is also known that thrombophlebitis in some patients involves hereditary factors, including mutations of genes that control the amount of clotting factors in the blood.

Questions have been raised in recent years as to whether frequent long-distance air travel increases the risk of thrombophlebitis in airline pilots and passengers. As of 2001, studies of the effects of long-distance flights on blood circulation in human test subjects have yielded conflicting results.