In interstitial cystitis or bladder pain syndrome (IC/BPS), the lining of the bladder is constantly irritated, causing pain during urination and urinary frequency. It is not certain why individuals have IC/BPS, but it is thought to be due to chronic inflammation of the bladder, possibly from defects in the inside wall of the bladder. It may also be partly an autoimmune disorder, in which the body makes substances that attack the lining of the bladder. Sometimes IC/BPS runs in families. IC/BPS occurs in men and women, but is 5 times more common in women. It may be more common than previously thought because individuals with other painful conditions of the pelvis may also have IC/BPS that has not been diagnosed. Your primary care doctor may refer you to a urologist, a doctor with specialized education in the management of problems with the urinary system, including the kidneys, the ureters, the bladder, and the urethra.