A few years ago my dad had one to look for a small intestine problem which was too far away from either end to run in a scope. It might be a matter of powering it for long enough to get through the large intestines. It's tough to swallow a D cell battery to power it for 24 hours.
They are much smaller now and not a problem to swallow. I was offered the opportunity for that procedure about a year ago, but I declined because it appeared the problem I had that put me in the hospital improved, and was not out of sight where only a camera would find it. So far so good. - Tom