Common causes of inexplicable ankle swelling: First, poor blood circulation in both lower extremities caused by standing for a long time or sitting for a long time. Secondly, inexplicable swelling of the ankles is a common cause of swelling of the feet in pregnant women in the second trimester. Third, idiopathic edema, these patients do not have a clear cause will appear leg swelling, after a night of rest, ankle swelling will appear to improve. Fourth, common pathological factors, such as kidney disease, heart disease, liver disease, etc. can lead to swollen ankles. Fifth, such as hypoproteinemia caused by malnutrition, patients will also have swollen ankles, and local lymphatic flow obstruction will also appear inexplicably swollen ankles.