Final answer:
Lymphedema is an abnormal accumulation of fluid due to improperly draining lymph vessels, causing swelling and is directly related to the lymphatic system's function.
Step-by-step explanation:
An abnormal accumulation of fluid that occurs when a vein or lymph vessel does not drain properly is known as lymphedema. This condition is characterized by swelling due to an excessive buildup of lymph fluid, which can occur due to various reasons, including surgery, radiation therapy for cancer, infection, or genetic predisposition. Unlike other options like hemorrhoids, arthritis, and asthma, lymphedema directly involves the lymphatic system and its inability to properly transport lymph. Edema, more generally, is the accumulation of excess fluid in the tissues, which can lead to swelling and is often associated with circulatory deficits.