Lymphedema is one of the many conditions that can occur when the lymphatic system is not functioning correctly. Lymphedema is a term used to describe localized fluid retention and swelling that is caused by a malfunctioning lymphatic system. Lymphedema has a number of causes, including genetic (hereditary), chemotherapy in cancer patients, and parasitic infection (Ure, 2013). There are a number of different symptoms – edema being the main one, but feelings of heaviness and fullness, skin changes, hyperkeratosis, and elephantiasis in the later stages (Schlogel et al., 2015). Lymphedema is caused by changes to the lymphatic system that prevent it from functioning correctly.
The lymphatic system usually transports lymph from the circulatory system to cells. Lymph then returns through the venous capillaries to normal circulation to blood, but a portion of this lymph, that containing proteins and cellular debris, returns through the lymphatic system to maintain a normal tissue fluid balance. In healthy people, this fluid exits the cells and is carried through the lymph system from lymph collectors, lymphatic vessels, through to the thoracic duct or right lymphatic duct, which return the fluid to the circulatory system (Schlogel et al., 2015).

In patients with lymphedema, this process is inhibited as the normal lymphatic drainage system is not working. If the lymph collectors are blocked or abnormal, or the rudimentary valves in the lymphatic vessels are not preventing backflow, the patient will see an increase in protein content in tissues, which causes the retention of water and swelling seen in lymphedema patients (Greene et al., 2015). The main alteration in lymphatic functioning in lymphedema is that the fluid is not being trained from the tissues and thus the lymph that would usually flow through the lymphatic system is not leaving the cells and tissues, thus causing a build-up of proteins and water.

References
• Greene, A. K., Slavin, S. A., & Brorson, H. akan. (2015). The Lymphedema Center and Multidisciplinary Management. In Lymphedema (pp. 51–55). Springer. Retrieved from http://link.springer.com/chapter/10.1007/978-3-319-14493-1_6
• Schlögel, M. J., Brouillard, P., Boon, L. M., & Vikkula, M. (2015). Genetic Causes of Lymphedema. In Lymphedema (pp. 19–31). Springer. Retrieved from http://link.springer.com/chapter/10.1007/978-3-319-14493-1_3
• Ure, C. (2013). [Diagnosis of lymphedema]. Wiener Medizinische Wochenschrift (1946), 163(7–8), 162–168.