Have air bubbles coming out of uretha been tested for fistula do not have what else can cause these bubbles?

Still maybe fistula: A fistula between the bladder and the intestines can be open intermittently, therefore tests such as cystogram, barium enema, and even cystoscopy and colonoscopy may not see the fistula. Best to the repeat the tests if the symptoms continue, may even consider surgery without definitive diagnosis if the problem is bad enough. Hope this helps!

GI evaluation: In the absence of a a severe bladder infection- passing air bubbles in the urine suggests a communication between the bowel lumen and the urinary tract and needs to be further evaluated until the cause is identified. Have a Gastroenterologist evaluate this with colonoscopy and other tests. Urologist would perform cystoscopy and imaging studies of the urinary tract with administration of a dye.