How Crohn’s Disease Changes Your Intestines

By Dr. Peter Higgins

Most people associate Crohn’s Disease with the symptoms that accompany it – pain, cramping, diarrhea, appetite loss, so on and so forth. What people don’t often realize is that the inflammation characteristic of Crohn’s Disease can cause irreversible damage to the intestines over time. The bowel wall is thickened during inflammation, due to the many white blood cells and water (swelling) that enter the bowel wall during a flare. As the bowel heals after a flare, scar tissue, or fibrosis, is left behind.

Scar tissue, strictures and adhesions

In the majority of Crohn’s patients, scar tissue develops within the intestinal walls as part of the healing of Crohn’s-related inflammation. Over time, this scar tissue buildup can cause narrowing of the gastrointestinal (GI) passage, which subsequently slows the movement of food and stool throughout the GI tract. The segment of GI tract that becomes narrowed is called a stricture.

The stricture results from a thickened intestinal wall. It can be from inflammation and edema (initially) or it can be from accumulated scar tissue. It is hard to tell the difference on a CT scan or MRI.

Strictures (if narrow enough) can cause intense pain and vomiting, and if they progress (i.e. the narrowing worsens), the intestine can actually become fully blocked. When a blockage occurs, medical intervention – which may include surgery – is necessary.

And although the prospect of surgery is unpleasant (to say the least), it may be more common than you think. In fact, an estimated 70% of Crohn’s Disease patients require some sort of surgical procedure to treat scar tissue buildup over the course of their disease.

While it may be prevalent, intestinal surgery comes with its own set of complications. Adhesions – or bands of scar tissue – may develop after an operation on (or trauma to) the GI tract. Adhesions run from the point of surgery to another part of the intestine (or another organ). For some people, these adhesions will be subtle, painless and self-correcting; for others they may twist or pull on the intestines, resulting in an obstructed GI passage. If this occurs, an additional surgery to treat the adhesive obstruction may be required.

We know that the Crohn’s Disease course varies from individual to individual, but often times its progression evolves from inflammatory, to stricturing, to (worst case scenario) penetrating disease.

Abscesses and fistulas

Penetration is another aspect of Crohn’s Disease that warrants further discussion. Because the inflammation associated with Crohn’s affects all layers of the intestinal wall, the wall may in turn become weak and susceptible to a wide range of structural issues. This intestinal weakness combined with scar tissue buildup (with subsequent narrowing of the GI tract and buildup of upstream pressure) may result in the formation of fistulas and abscesses.

Abscesses and fistulas occur when the inflammation penetrates through all layers of the digestive tract.

A narrow stricture results in high pressure upstream, and associated inflammation makes the intestinal wall weak. The combination of high pressure and a weakened wall allows the intestinal contents to penetrate the wall and relieve the built up pressure. When this penetration occurs, it often leaves behind a little passage or tunnel – this is called a fistula. In Crohn’s Disease, fistulas may develop between a section of intestine and an outer organ (like the skin), an inner organ (like the bladder) or another part of the intestine.

Typically, fistulas occur where there are areas of high intestinal pressure combined with a weakened wall. High pressure occurs in strictures (and just upstream of strictures), or just upstream of the anal sphincter. Most patients with IBD develop really strong sphincters, because they have a lot of practice at holding in bowel movements. Given this tendency, many Crohn’s Disease patients develop fistulas in and around the anus.

Among a variety of symptoms, anal fistulas can cause irritation of the skin around the anus, leakage of fluid or pus, and occasionally a leak of fecal matter. Treatment typically involves a combination of medication and surgery; the approach varies depending on severity of symptoms, fistula location and number/complexity of fistula tracts. Talk to your doctor immediately if you suspect you might have a fistula – earlier intervention is always preferred.

Abscesses are little pockets of infected fluid and pus that develop when the contents of the bowel leak through the intestinal wall but are walled off by your immune system before they can cause more harm. They can cause pain and discomfort, and while some drain on their own, many require medical intervention to drain the infected fluid.

But it all starts with inflammation

It can be upsetting and overwhelming to think about the numerous ways in which Crohn’s Disease can compromise your digestive system and threaten your health. But by understanding how the disease progresses and recognizing the signs and symptoms of its related ailments, you can stay on top of your condition and exercise more control over your life.

Suggested: Learn about the different treatments for Crohn's disease.

Remember – inflammation is the precursor for many Crohn’s-related complications. And although inflammation doesn’t always cause symptoms, it can silently wreak havoc on your intestines. Be vigilant about seeing your gastroenterologist and ensure that he or she is assessing your inflammation levels and modifying your treatments accordingly. You’ll be glad you did.

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