When you have Interstitial Cystitis

The bladder stores urine (your body's liquid waste) until it's passed out of the body. What happens in the bladder to cause Interstitial Cystitis is not clear, but some changes have been observed. The protective lining that keeps urine away from the bladder walls may become thinner. The walls may stiffen and harden so the bladder can't expand to hold urine.
During certain tests, pinpoints of bleeding (glomerulations) may be seen on the bladder wall. Rarely, a crater (called a Hunner's Ulcer) may also be found.