Passing gas (air) in the urine, a rare symptom, usually indicates an abnormal opening (fistula) between the urinary tract and the intestine, which normally contains gas. A fistula may be a complication of diverticulitis, other types of intestinal inflammation, an abscess, or cancer. A fistula between the bladder and the vagina may also cause gas to escape into the urine. Rarely, certain bacteria in the urine may produce gas.
Doctors do a pelvic examination in affected women. To diagnose fistulas, doctors may insert a flexible viewing tube into the bladder (cystoscopy) or colon (sigmoidoscopy), or both. Sometimes imaging tests, such as computed tomography (CT), magnetic resonance imaging (MRI), or ultrasonography, are done.
Fistulas are usually repaired surgically.
(See also Overview of Urinary Tract Symptoms.)