BenBurch
Gatekeeper of The Left
Hmm well the proximity of the two are very close but the bladder has ureters entering it whereas the stump of the colon would not have ureters. I vote for a fistula between the stump of the colon and the bladder as the most likely explanation although who knows since they say that this type of problem has been previously documented.
He might have sutured them together causing a fistula.