The Lymph System

To understand lymphedema, it helps to understand the function of the lymphatic system, which includes an extensive network of lymph vessels and lymph nodes.

The lymphatic system helps coordinate the immune system’s function to protect the body from foreign substances.

Here’s how the lymphatic system works:

  • Excess fluid is collected from the space between tissues in the body and moves through the lymph vessels.
  • The fluid (now called lymph) isn’t pumped through the body like blood, but instead is “pushed” through the lymph system as the vessels are compressed by surrounding muscles. These vessels are different from arteries and veins, which carry blood.
  • Filters called lymph nodes remove certain harmful substances from the lymph fluid, such as bacteria and debris. The fluid from most tissues or organs is filtered through one or more lymph nodes before draining into the bloodstream.

What is lymphedema?

Lymphedema is an abnormal buildup of fluid that causes swelling, most often in the arms or legs. The condition develops when lymph vessels or lymph nodes are missing, impaired, damaged or removed.

There are two types of lymphedema: primary and secondary.

  • Primary lymphedema is rare and is caused by the absence of certain lymph vessels at birth, or abnormalities in the lymphatic vessels.
  • Secondary lymphedema occurs as a result of a blockage or interruption that alters the flow of lymph through the lymphatic system and can develop from an infection, malignancy, surgery, scar tissue formation, trauma, radiation, or other cancer treatment.

Lymphedema can occur within a few days, months or years after lymphatic injury.

What are the signs and symptoms of lymphedema?

Symptoms of lymphedema include swelling in the arms, hands, fingers, shoulders or legs. The swelling may occur for the first time after a traumatic event (such as bruises, cuts, sunburn, and sports injuries), after an infection, or in the part of the body that was treated for cancer.

If you have any of these symptoms, talk to your health care provider. Prompt treatment can help manage the condition before complications occur.

Last reviewed by a Cleveland Clinic medical professional on 07/16/2019.


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