When I had my abdominal fistula the color would change all the time, to be honest it depended on what I ate. If I ate something with seeds in it, then seeds would litterally come out of it, or something with lettuce, parsley or spices (sorry for the TMI). I had periods of heavy drainage, and light drainage. My surgeon called it "waxing over"...basically ment that it would get clogged up and have very little drainage to none for a few days, then the clog would break
open and I would have heavy drainage.
What I found worked best for me was packing the fistula with gauze, placing 3 thick squares of gauze over that, taping it up...then I found these clear plastic medical sheet stickers, you stick them on and peel back the top layer and a thin plastic cover would stay on.