To diagnose vesicointestinal fistula, your doctor will take your history of passing feaces and gas through the urethra and do a physical examination. S/he may order tests, eg ultrasound, MRI, CT, injecting visible dye into the bladder and observing the dye in stool, endoscopy(examining the intestines through a tube fitted with a camera), cystoscopy(examining the bladder through a tube fitted with a camera).
Attribution: Avallain