Having a blood clot or deep vein thrombosis (DVT) of the lower extremities can be very serious. Swelling in one leg without an obvious cause is suspicious for a blood clot that I suggest you see a doctor
to be evaluated so it can be ruled out. DVTs can sometimes break off and travel to the heart and lungs causing sudden shortness of breath and sometimes sudden death. It can also cause, although rarely, a stroke in people with a heart defect. Those individuals with high risks for deep vein thromboses include hip fractures or major orthopedic surgeries, prolonged bed-rest, obesity, patients on oral contraceptive pills (OCP) or Tamoxifen, smokers, history of cancer. Patients with clotting disorders (i.e. anti-lupus antibody or factor V leiden deficiency) are especially at high risk for developing blood clots. In fact, up to 30% of those found to have a DVT or pulmonary emboli had factor V leiden deficiency. In obese patients, it is difficult to tell how one side may be different than the other so it is necessary to get a professional consult and possibly an ultrasound
to rule it out. It is a quick test and its sensitivity is very good. The treatment for it depends on where in the veins the clots locate. The more proximal is or larger veins (those in the pelvis) are, the most high risk for breaking off and causing a pulmonary embolis, whereas the superficial calf veins clots typically do not cause any serious harm. You need to consult with a primary care doctor
to determine whether you have it and which type you may have. Again, please see a doctor right away.