Inactivity due to a medical condition such as paralysis is one medical cause of blood clots in the legs, according to WebMD. Cancer can also cause blood clots in the legs, as can damage to blood vessels that occurs as a result of injury or surgery.
A blood-clotting disorder, pregnancy, certain medications and smoking can also lead to the development of blood clots in the legs, adds MedicineNet. While small blood clots in the leg do not produce any symptoms, others cause redness, swelling and pain. The leg may become swollen, feel warm and appear red, notes WebMD. The pain may worsen when the individual stands or moves, and the pain may become persistent. Blood clots that break away from their original location can travel to other parts of the body, such as the lungs, where they can cause life-threatening situations, states Mayo Clinic.
An ultrasound can detect blood clots, advises WebMD. Treatment involves administration of blood-thinning medications for at least three months, elevating the legs, wearing compression stockings and taking walks. To prevent the development of blood clots in the legs, individuals can avoid sitting for extended periods of time, exercise their legs and wear compression stockings. Following surgery or illness, it is best for the patient to get out of bed as soon as possible to increase circulation in the legs. Doctors often prescribe anticoagulants postoperatively to patients to prevent formation of blood clots.