I'm not sure, but I think that might be the iliosecal valve (spell?)...connects the small and large intestine. I can't remember exactly, but I saw a holistic MD a few years ago who showed me that spot - exactly in the middle of that line between the belly button and hip bone, she told me that valve gets stuck on a lot of people and showed me how to massage it, though now I can't remember the procedure. I don't know if a colonic will go that high.