Your bladder is a hollow, muscular, balloon-shaped organ that stores urine until you're ready to empty it. In a healthy urinary system, the bladder can hold 8 to 10 ounces of urine comfortably for 2 to 5 hours, depending on how quickly it fills.

No one knows what causes interstitial cystitis. Experts suspect that it's a syndrome with more than one cause rather than a single disease. So far, two types have been identified:

• Nonulcerative. Ninety percent of people with interstitial cystitis have the nonulcerative form, in which pinpoint (petechial) hemorrhages, also known as glomerulations, may occur on the bladder wall.

• Ulcerative. The bladder of a person with ulcerative interstitial cystitis has ulcers, also known as Hunner's patches.

Some people with the condition have neither glomerulations nor ulcers.

Symptoms of interstitial cystitis resemble those of a UTI. However, urine cultures of people with interstitial cystitis usually prove to be free of bacteria. Experts have put forward a number of causal theories, including that interstitial cystitis is an autoimmune, infectious or allergic condition, but none has been proved.

Interstitial cystitis appears to be associated with other chronic conditions, such as irritable bowel syndrome, vulvodynia, fibromyalgia and endometriosis. Also, people who have repeated urinary tract infections may be more prone to interstitial cystitis.

• Endometriosis
• Fibromyalgia
• Cystitis
• Cystitis, interstitial
• Irritable bowel syndrome (IBS)
• Urinary tract infection - (UTI)
• Vulvodynia

The condition primarily affects women between the ages of 30 and 70, but men and children also may experience interstitial cystitis.