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7 Causes of Constipation in Crohn’s Disease

Did You Know that Constipation Could Delay Getting a Diagnosis of IBD?

People usually do not associate constipation with Crohn’s Disease since diarrhea and urgency are much more common symptoms of the disease. In some cases constipation can even delay a diagnosis of Crohn’s disease or ulcerative colitis and in other cases a patient who has already been diagnosed with IBD might not realize that the constipation they are experiencing could be a sign of a serious problem.

Constipation is when a person has a bowel movement less often than what is normal (for them), or has the sensation that they were unable to evacuate the bowels completely, or straining during bowel movements. 

7 Causes of Constipation in Crohn's Disease

1. Strictures

A stricture is a narrow portion in the intestine that can make it difficult for contents in the digestive tract to pass through. 

Let's Get More In-Depth!

Scar tissue/fibrosis in the walls of the intestine can cause the intestinal lumen to become narrow. The lumen is the inside space of a tubular structure. You can think of a lumen like an enclosed water slide tube. The hollow area of the tube is what you would travel through as you go down the slide. In the intestine the hollow open area (the lumen) is what food, fluid, and air travel through. If somewhere in the lumen there is a narrow segment then whatever is traveling through it might get stuck or have difficulty passing by.

Visualize It!

It can be helpful to envision what happens with a clogged pipe when trying to understand how strictures affect the way contents move through the digestive tract. 

When a pipe has excessive mineral buildup the inside becomes narrow and your drain starts to back up or will not drain at all. This is similar to what happens when someone has a stricture. Contents in the digestive tract cannot pass through, or have difficulty passing through, which can cause constipation. These narrow areas of the intestine (strictures) can cause a lot of pain, nausea, cramping, and vomiting in addition to constipation. No one wants clogged “pipes!”

What have we learned so far?

The lumen is the open space inside of a tubular structure. The hollow, open space in the intestine is the intestinal lumen.

If the lumen becomes narrow in an area of the intestine that narrow area is called a stricture.

Strictures can make it difficult for contents in the digestive system to pass by them. Sometimes they can completely block the intestine. They can make eating painful, change bowel habits, and cause nausea and vomiting.

Even More In-Depth: What Causes Strictures in Crohn's Disease?

Crohn’s disease is an Inflammatory Bowel Disease (IBD) that involves periods of time where the disease is active and inflammation is present and periods of time where the disease is quiet/in remission. The recurring cycles of inflammation and healing characteristic of Crohn’s disease cause scar tissue to form in the intestine. This scar tissue is known as fibrosis. Fibrosis can continue even once the inflammation is under control.

Visualize It!

Inflammation is the way our body responds to an injury and almost all injuries result in the formation of scar tissue. I’m sure you’ve witnessed this yourself at some point in your life when you’ve been injured. Let’s just imagine if you will that it’s a hot summer day in June before your 6th grade year. You and your best friend decide to go swimming at the Clubhouse pool in your neighborhood. She’s riding her bike and has you on the handlebars and suddenly her towel gets caught in the wheels and you go flying forward and hit the ground and she runs over you with the bike. You know, that ol’ scenario. Very common. 

Your knees are all scraped up so she pours peroxide on them to clean them out. They are red and inflamed and hurt like a bitch but eventually the wounds heal and scar tissue replaces your once scar-free knees. The scar is composed of fibrous tissue that replaces the healthy tissue that was there before the injury.

 In this process new protein fibers are created and are composed of the same protein (collagen) as the tissue it replaces but now the fibers are reorganized/aligned differently than they were in the healthy tissue. You might notice that the skin on your knees isn’t the same as it used to be. It is now thicker, tight, and less flexible and has a different texture because of the disorganized scar tissue that has formed there.

This same process happens inside the digestive tract of someone living with Crohn’s disease because of the recurring cycles of inflammation and healing in the gut. Active disease means damaging inflammation and once healing begins the healthy tissue is replaced with disorganized scar tissue. When scar tissue builds up in the walls of the intestine it thickens and the intestinal lumen can become narrow. Just like the scraped knee the tissue in the intestine becomes thicker, less flexible, and functions differently.

Strictures in Crohn's Disease can be Inflammatory, Fibrotic, or More Commonly a Combination of Both.

Strictures in Crohn’s disease are not just fibrotic. They can also be inflammatory or more commonly a combination of both fibrotic and inflammatory. 

Constipation can be a symptom due to fibrostenosis in the intestinal lumen. 

2. Fear

You probably didn’t expect fear to be listed as a cause of constipation in Crohn’s disease. If a person with Crohn’s has anal fissures, perianal abscesses or a fistula they may fear using the bathroom because these things can cause very severe pain. Many patients understandably try to avoid using the bathroom for as long as possible to not have to experience that pain. The longer a person is able to avoid using the bathroom the harder the stool can become which can make it difficult to pass; resulting in constipation.

3. Adhesions

After a person with Crohn’s Disease has a colorectal surgery (E.g. bowel resection or colectomy) adhesions are likely to form.

Adhesions are bands of scar tissue that join structures together with glue-like bonds that can prevent the bowel from functioning properly. They begin at the point of surgery and can run to other organs, other parts of the intestine, or form in the lining of the abdominal cavity. 

Sometimes adhesions will strangle the bowel reducing it’s diameter which could lead to constipation. Other causes of constipation due to adhesions are if the adhesions cause the intestine to become fixed to another organ and it gets twisted. This twisting of the intestine creates an obstruction.  Adhesions that bind loops of bowel together can also cause constipation. 

4. Medications

Certain medications used to manage Crohn’s Disease can cause constipation. For example narcotics used to treat pain or iron supplements used to treat iron deficiency anemia. 

5. Post Operative Ileus

A post operative ileus is very common after abdominal surgery and usually resolves on it’s own within a few hours to a few days. The digestive tract is a long continuous tube that starts at the mouth and ends at the anus. Inbetween you’ll find the esophagus, stomach, small intestine, and large intestine.

Wave-like contractions in the digestive system that propel contents through it is called peristalsis.

Food, fluid, and air moves through the digestive system by a process called peristalsisPeristalsis involves alternating contraction and relaxation of the muscles in the digestive tract to propel contents forward and through it. Sometimes after abdominal surgery peristalsis stops working like it normally does, either slowing down 

the rate contents travels through the digestive system or completely stopping it. 

When this happens it’s called a post operative ileus or paralytic ileus. You’ll often hear doctors and their patients talking about waiting for the bowels to “wake up” after surgery before they can attempt eating. If not for peristalsis the food that we eat and the liquids that we drink would just sit there and pool and eventually back up. With an ileus the bowels behave just like they would if a physical blockage like a tumor was blocking the lumen of the intestine but there is no physical blockage present. It’s the abnormal peristalsis that causes the digestive tract to look and behave like a physical obstruction is present. Symptoms of a post operative ileus include abdominal distention, nausea, pain, vomiting, and constipation.  

6. Inflammation

Are you surprised to see inflammation listed as a cause of constipation? Normally we picture the exact opposite of constipation when we think about active disease in the digestive tract.

Inflammation located in the rectum is called proctitis. The rectum is an amazing part of the digestive system that is highly intelligent – it’s even capable to tell the difference between gas and stool (when working properly). The rectum’s primary job is to hold waste until you have a bowel movement. 

People with proctitis often experience urgency and frequent trips to the bathroom so many of them do not realize that they are constipated. Someone might think they are having bowel movements several times a day because of the urgency they feel that has them running to and from the bathroom all day long. In reality they’re just passing blood and mucous and only pass stool every few days. Proctitis can cause constipation with spasms, a sensation that you haven’t completely emptied the bowels, and straining. The rectum does not stretch when inflammation is present which leads to spasms and urgency. 

gif of flame burning

7. Hernia

illustration shows pinched loop of intestine buldging out of abdominal cavity

A portion of the bowel may protrude through the abdominal wall; this is known as a hernia. If the loop of bowel that protrudes through the abdominal wall is tightly pinched, the kink in the bowel could make it difficult for stool to move through and cause constipation. 

It's Important to Talk to your Doctor

It’s important to talk to your gastrointerologist if you have constipation. Some of these causes of constipation in Crohn’s Disease can be fixed easily. For example if you are taking oral iron supplements for iron deficiency anemia switching to IV iron infusions could work better for you. Other causes of constipation in Crohn’s Disease indicate a serious problem that needs to be addressed. 


Test your understanding by taking the quiz. Try to do it without looking up the answers!

Causes of Constipation in Crohn’s Disease

Dedicated to Jessica

The story I shared in this post about my friend running me over with her bike (haha) is a true story. My friend Jess was my very best friend growing up. She was diagnosed with Crohn's disease years after I was and passed away after complications from a colorectal surgery.
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