First and easiest things to do if you are retaining fluid are to drink extra water, which will help your body clear the extra sodium in your tissues, and then cut back on the sodium in your diet to keep the fluid from building back up. If it does, you should get checked by your doctor to make sure your kidneys are working correctly.
First, if you are retaining fluid, your Dr needs to know about it because there are a couple of reasons what could be wrong. You could have DVT (deep vein thrombosis), and possibly heart problems. You need to limit your intake of fluids, your Dr will probably put you on a diuretic. If you have ted hose or support hose wear those it will help. Elevate your lower extrema ties, watch it closely to see if it continues to swell up more, if so go to the er.