Bilateral leg edema is swelling of the soft tissues of the legs. The condition can be merely a daily nuisance, or signal a serious underlying condition. A physician should be consulted to determine the cause and begin appropriate treatment. It has a number of causes, both anatomic and systemic.
The heart takes blood from the body, pumps it to the lungs, takes it back to the heart, and returns it to the body. In heart failure the heart pumps inadequately. Bilateral leg edema can occur in heart failure, particularly if it occurs on the right side of the heart, this is the side that takes the blood from the rest of the body and directs it to the lungs. If the right side of the heart fails, the blood and fluids back up into the body, and much of the fluid collects in the legs.
Various kidney diseases are associated with bilateral leg edema. In nephrotic syndrome, the kidneys lose proteins that are responsible for keeping fluids in the vascular system. Without the protein, fluid leaks into the tissues. When a person stands up, the force of gravity forces most of the fluid out into the legs. Other problems in nephrotic syndrome include high fat and cholesterol and sometimes high blood pressure. Nephrotic syndrome is caused by various immune system disorders, infections, drugs and cancers.
Liver failure results in the liver not being able to make the proteins used to keep fluid out of the tissues and in the blood vessels, leading to leg edema. Liver failure can be caused by infections such as hepatitis B and C, immune system disorders, disorders of metabolism or toxins such as high doses of Tylenol and alcohol.
Myxedema means hypothyroidism, or low levels of thyroid hormone in the blood. Symptoms include bilateral leg edema and a number of others. Some of the other common symptoms are fatigue, lethargy, cold intolerance, weight gain, depression, slow speech, forgetfulness, constipation and coarse skin.
Blood clots can get lodged in the deep veins of the legs or pelvis. This restricts the flow of blood out of the legs towards the heart, and the leakage of fluid into the tissues. Such a clot is called a deep vein thrombosis. Certain genetic disorders make a person more susceptible to getting a DVT, as do smoking, oral contraceptive use and cancer.
Edema caused by venous insufficiency refers to veins in the legs being to structurally insufficient to keep the fluid in blood from leaking out into the tissues. Unlike arteries, veins have one-way valves that prevent the back flow of blood. If the valves are damaged, blood will be more likely to flow back away from the heart and towards the tissues.
Lymphedema is edema caused by obstruction of the lymphatic system. Some types of lymphedema are hereditary, causing defects in lymph nodes or channels. Others are acquired, such as tumors or infections blocking the lymph channels.