I had edema once, a few years ago. Both feet but not the ankles. I googled it and read that the answer was to raise the feet for 3 or 4 hours. As I was still in bed I made pile of laundry etc at the other end, rested my feet on it and after about 3 hours the swelling had cleared.
Google in fact said do this for several days so I did it for 2 more.
Never happened before and never happened since. Strange.
Well you asked about edema.