The causes of a venous insufficiency can be :
- inherent varices (varicose veins) or a
- condition after a thrombosis (so-called post-thrombotic syndrome)
Veins serve in the transportation of blood to the heart ; they have to carry the blood upstream. In order to prevent the pressure from being too great, the veins have, especially in the legs, a valve every 0,5 to 1 cm. These valves prevent the backflow of blood. In the case of varicose veins, these valves do not close correctly, which in turn leads to a strong pressure increase in the blood vessels located in the lower part of the legs, furthest from the heart. Through this higher pressure, more fluid from the blood vessels is filtered into the tissues. This fluid surplus is what a physician calls edema. The lymphatic system is an additional draining system of the tissues which removes not only fluids but also waste products. A simple surplus in tissue fluids can be reabsorbed by the vessels if the legs are lifted ; this might be the case if the legs are back to their thinner state in the morning. If a surplus in waste products subsists in the tissue, lifting the legs is not sufficient anymore, and they are still thick comes morning. The tissue hardens, and phlebedema becomes phlebo-lymphedema. 
Therapy:
The therapy of choice in troubles caused by varicose veins (heavy legs, prickling sensations in the legs, cramps) and/or edema are compression stockings. Knee-high stockings are more often than not sufficient. To reach their full effect, the stockings should always be worn, especially during warmer periods.
Because most afflicted people do not wear the stockings, the abnormal veins should be surgically removed in order to prevent further negative consequences. This specially applies to younger patients.
The therapy of choice in a case of phlebo-lymphedema is thus the Combined Decongestive Therapy (Manual Lymph Drainage according to Dr. Vodder, bandaging, motion therapy, as well as nutrition and skin care).