How Arm Lymphedema Happens
Lymphedema of the arm is an accumulation of lymph fluid in the soft tissues of the arm, with accompanying swelling (also called edema). To understand how it happens, you have to know a little bit about how blood and lymphatic fluid move around your body.
To keep from getting backed up, fluid has to keep moving within networks of vessels and channels. Blood travels from your heart to your arm in arteries and capillaries (the small blood vessels that connect arteries to veins). As the blood moves through the capillaries, it drops off important supplies to the cells in your arm: oxygen, nutrients, and a clear, colorless fluid called lymphatic fluid. The used blood keeps moving and travels back to the heart and lungs, where it gets refreshed. With every beat of your heart, fresh blood returns to your arm with fresh supplies.
Lymph fluid also has to keep moving through the tissues of the arm back into the bloodstream. This fluid flows in another type of vessel, called lymphatics.
The muscles in your arm and contractions in the walls of the lymphatic channels push lymphatic fluid up your arm. Valves in the lymph vessels keep fluid moving forward. The lymphatic channels pass through bean-shaped structures called lymph nodes, which are located under the arm, and in the neck, groin, and other areas. Lymph nodes filter out bacteria, waste products, and toxic substances from the lymphatic fluid. The trapped material is broken down and excreted from the body. Eventually, the used lymphatic fluid leaves the arm, joins the used blood within the veins, gets refreshed in the lungs, and is then pumped back to the tissues by the heart.
Lymphatic fluid contains lots of nutrients. It's an easy target for bacteria that may find their way past the protection of the skin. Bacteria can get in even through something as seemingly innocent as a torn cuticle or a splinter. If bacteria do get in, they can cause infection. Infection, in turn, results in increased blood flow to fight the bacteria—and more lymphatic fluid accumulating and needing to be drained away.
You can think of lymphedema as a plumbing problem: Veins and lymphatic channels are like pipes and drains that can handle the normal load of lymphatic fluid. If lymph nodes and channels are removed, there might not be enough pipes and drains to handle all the fluid.
This can become a real problem when blood flow to your arm increases because of an infection, a burn, overusing the muscles of the arm, or even a bug bite. In these situations, the increased amount of lymphatic fluid flowing in can sometimes be too much for the arm's lymphatic vessels. If the fluid channels can't keep up with all that extra fluid, the fluid begins to back up and gather in the spaces between the cells of your arm's soft tissues. These tissues include the skin, fat, muscle, nerves, blood and lymphatic vessels, and connective tissue. The swelling resulting from this buildup of lymphatic fluid is called arm lymphedema.
Lymphedema can affect the whole arm or only a limited portion, such as the hand, the wrist area, the area below the elbow, or, much less often, only the area above the elbow. Lymphedema can also affect the breast area, because the fluid from that area also needs to drain through the underarm to get back into circulation.
Some women have mild lymphedema, which is hardly noticeable. Some develop moderate lymphedema that may be noticeable, tends to persist, and gets worse when aggravated. Others have severe lymphedema that is very uncomfortable and even disabling. For all of these cases, there are treatments that can help ease the discomfort and lower the swelling.