Chronic Venous Insufficiency: This condition is a common cause of bilateral lower extremity edema, especially in individuals with a history of prolonged standing, obesity, or previous venous thrombosis. The edema is typically more pronounced in the ankles and legs.

Heart Failure: Edema in bilateral lower extremities can be a sign of right-sided heart failure, where the heart is unable to pump blood effectively, leading to fluid buildup in the body.
Nephrotic Syndrome: A condition characterized by excessive loss of protein in the urine, leading to hypoalbuminemia, which causes fluid to leak out of blood vessels and into the interstitial space, resulting in edema.
Liver Cirrhosis: Cirrhosis can lead to hypoalbuminemia and portal hypertension, both of which can cause edema in the lower extremities.
Hypothyroidism: Although less common, hypothyroidism can cause edema due to the accumulation of mucopolysaccharides in the skin and other tissues.

Deep Vein Thrombosis (DVT): A potentially life-threatening condition that requires immediate medical attention. DVT can cause unilateral or bilateral edema, and it's crucial to rule out this diagnosis to prevent pulmonary embolism.
Lymphoma or Other Malignancies: Certain cancers can cause edema by obstructing lymphatic or venous return. Although less common, these diagnoses are critical not to miss due to their significant implications for treatment and prognosis.
Pulmonary Embolism: While pulmonary embolism itself does not directly cause edema, it can be associated with DVT, and the edema might be a presenting symptom of a larger thromboembolic event.

Lipedema: A rare condition characterized by the abnormal growth of fat cells in the legs, leading to swelling and edema.
Fabry Disease: A genetic disorder that can cause edema among other systemic symptoms due to the accumulation of a particular type of fat in the body's cells.
Milroy Disease: A rare, inherited condition that affects the lymphatic system, leading to chronic swelling (lymphedema) of the legs.