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The position of the bladderThe bladder is a balloon-shaped organ, which sits in the pelvis, in front of the uterus. Waste fluids are filtered out of the bloodstream by the kidneys, and collected in the bladder as urine. From the bladder, urine passes out of the body through a hollow tube called the urethra.

The bladder has an outer wall of muscle and connective tissue. Nerves in the wall monitor the bladder filling and signal the body to urinate. Like other organs, the bladder's inner surface is lined with epithelial cells. When a woman has interstitial cystitis (IC), these cells become irritated and inflamed. Areas of pinpoint bleeding, called glomerulations, or larger sores, called Hunner's ulcers, may appear in the lining of the bladder.

The Cause of Interstitial Cystitis

Normally, the inner wall of the bladder is coated with a substance called glycosaminoglycan (GAG). This is a mucus-like layer that protects the epithelial cells, by preventing acids and toxins in the urine from coming in contact with this layer of tissue.

The structure of the bladderThe cause of IC remains unknown; however, some researchers speculate that the protective GAG layer of the bladder may be disrupted in some way, allowing substances in the urine to irritate the underlying epithelial cells.

There are several possible causes:

  • An unidentified infection, possibly a viral infection, may disrupt the GAG layer or damage the wall directly.
  • Some substance in the urine may be causing the damage.
  • After initially responding to a bladder infection, the body's immune system may have begun to attack the bladder's tissues or the GAG layer.

Immune system cells, called mast cells, have been found in higher concentrations in the bladder walls of women with IC. These cells release histamines, which may be partly responsible for the inflammation of the bladder wall. Histamines cause similar inflammation of the nose and upper respiratory tract when a person has hay fever or other allergies. This immune response may be the cause of IC or it may be the body's attempt to protect the bladder from some other threat.

Why Does Interstitial Cystitis Cause a Person to Urinate Frequently?

As the epithelial cells of the bladder wall are damaged, they may become scarred and stiff. This makes the bladder less flexible and less able to expand. In some cases, the nerves in the bladder wall may also be irritated or damaged, prompting the urge to urinate more frequently.


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Interstitial Cystitis

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