Can a Colonoscopy Detect IBS? What You Need To Know

Irritable bowel syndrome (IBS) is a combination of symptoms that may include bloating, gas, abdominal cramping, as well as difficulties digesting certain foods. 

It can be challenging for your healthcare team to diagnose IBS because the symptoms overlap with many other digestive health conditions.

The similarities can make it hard to identify the root cause of your symptoms, which can delay a proper treatment plan. 

Keep reading to learn more about reliable tests for gut health disorders and if a colonoscopy can detect IBS.  

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Can a Colonoscopy Detect IBS?

During a colonoscopy, your doctor inserts a small tube with a video camera into your rectum and colon.

You’re given anesthesia before the procedure, and the test typically takes less than an hour. 

Although the camera is perfectly positioned to examine your bowels, a colonoscopy can’t detect IBS.

The condition doesn’t change the appearance or structure of your bowels, and the tissues of your intestinal wall may look the same as someone without IBS.

Even a biopsy (a tissue sample) sent to a research lab can’t detect IBS (at least for now). 

Health scientists suspect the lack of physical evidence for IBS in the bowels is because the symptoms are linked to alterations in gut-brain communication—not physical abnormalities. 

This “broken telephone” effect can cause several functional gastrointestinal symptoms, such as changing the rate of food passing through the GI tract, which can alter bowel movement frequency. 

How Does a Colonoscopy Help Diagnose IBS?

A colonoscopy isn’t used to diagnose IBS but can rule out other conditions with similar symptoms. 

Your doctor or specialist will likely want to try less invasive assessments first—like blood work and stool sample collection.

They may order a colonoscopy as a “last step” in the diagnostic process.

However, an exception might be people experiencing digestive symptoms and are at high risk for colorectal cancer.

In these cases, guidelines suggest completing a colonoscopy sooner than normal-risk people. 

Just so you know—having IBS doesn’t put you at high risk, but having inflammatory bowel disease (IBD) or a family history of colorectal cancer does.  

Preparing for a Colonoscopy

It takes a full day to prepare your bowels for a colonoscopy.

Before having the procedure, you’ll need to avoid eating solid food for twenty-four hours, take laxatives to “clean out” your bowels, and organize a ride home after the procedure. 

Bowel Prep

Bowel prep includes emptying your bowels of as much stool as possible.

This is essential so the doctor has an unobstructed view of your intestines during the colonoscopy. 

To prepare your bowels, your doctor will recommend laxatives, which may consist of one or two rounds of medication. 

The health clinic staff should provide clear instructions on when to take the laxatives for best results. 

Dietary Restrictions

To prepare for a colonoscopy, stop eating solid foods approximately twenty-four hours before your procedure. 

You'll follow a clear liquid diet to stay hydrated and have some nutrition.

You can consume liquids free of vegetables, meats, or other solid ingredients. 

Here are things you can eat: 

• Fat-free broth or stock. 
• Plain coffee or tea (no milk or cream). 
• Sports drinks (orange, lime, lemon). 
• Pulp-free fruit juice (apple or white grape. Avoid cloudy or opaque options, like orange or pineapple). 
• Water. 
• Jello (orange, lime, lemon). 

Medication Adjustments

Due to the necessary dietary changes for a colonoscopy, antihyperglycemic medications (drugs prescribed to lower high blood sugar) and insulin may need to be adjusted. 

Taking these drugs without consuming carbohydrates may cause dangerously low blood sugar levels, a condition called hypoglycemia. 

To be safe, avoid making changes on your own.

Ask your physician or prescriber to review any necessary adjustments with you. 

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During and After the Procedure

When you arrive for a colonoscopy, you’ll be given a patient gown to change into.

Once ready, clinic staff will insert an intravenous needle (IV) into a vein in your hand and start administering sedatives to put you to sleep. 

During the procedure, your doctor will insert a flexible tube with a camera into your anus and examine your rectum and colon.

The device pumps air into your bowels to help your doctor see better during the examination, and this extra air might cause flatulence and bloating once you’re awake. 

Your doctor will check for healthy pink tissues and may remove colon polyps (small tissue growth).

Although most polyps are benign, some colon cancers can begin as a polyp, and removing them is a preventative measure. 

After the Procedure

After your colonoscopy as anesthesia wears off, clinical staff will monitor you closely for 30-60 minutes until you’re fully alert.

You can’t drive or leave the clinic alone; a caregiver or friend must take you home. 

You may continue having loose stools for a few hours after the procedure, especially after reintroducing foods into your diet.

This is a side effect of the laxatives, and you can eat bland foods (bananas, rice, boiled chicken, toast, and apples) until your stomach settles. 

When to Seek Care 

A colonoscopy is generally safe, but complications can occur.

If you experience any of the symptoms below, you should seek medical care immediately: 

• Bloody stools that don’t improve.
• Continuous bleeding from the anus. 
• Severe abdominal pain.  
• Fever. 
• Dizziness. 
• Weakness. 

Are there Other Diagnostic Tests for IBS?

Right now, there isn’t a test to diagnose IBS.

However, your doctor may order tests to rule out other possible conditions.

This is a process of elimination, which is still valuable because IBS symptoms overlap with other severe digestive disorders. 

Aside from a colonoscopy, some additional diagnostic tests your physician may order to assess your gut health include: 

• Blood tests to assess for nutrient deficiencies, inflammatory markers, and other signs of possible bowel disease. 
• Stool sample tests are sent to a lab and assessed for infections and signs of disease. 
• Hydrogen breath tests to assess for small intestinal bacterial overgrowth (SIBO). 
• Upper gastrointestinal endoscopy (a tube with a camera inserted through the mouth) with a biopsy sample to rule out celiac disease. 

As well as completing tests, your doctor should review your symptoms with you at length.

The details could reveal something critical that may affect your treatment plan, such as opting to introduce medications. 

While expressing your concerns, include details about changes to your stool consistency, bowel movement frequency, and any pain before or after defecating. 

Have IBS symptoms? Take the IBS quiz understand whether or not you have IBS.

Conditions that Mimic IBS

Typical symptoms of IBS may include pain in your abdomen, changes to your bowel movements (diarrhea or constipation—sometimes both), bloating, and whitish mucus in stool. 

Unfortunately, these symptoms are relatively generic and may mimic other digestive conditions—making it harder to diagnose the root cause of the symptoms. 

Other conditions that mimic IBS include:

• Celiac disease.
• Lactose intolerance.
• Small intestinal bacterial overgrowth (although you can have both IBS and SIBO).
• Food allergies. 
• Irritable bowel diseases such as ulcerative colitis.  

Bouts of stress can worsen gut health symptoms (even if you don’t have IBS). 

If you notice your stress levels have increased, it could affect your digestive health.

Diet changes may help, but seeking mental health support could relieve the symptoms long-term (and teach you how to handle future bouts of stress). 

Have IBS symptoms? Take the IBS quiz understand whether or not you have IBS.

Importance of Proper Diagnosis

Receiving a proper diagnosis is critical to developing an effective treatment plan.

With one, you might be able to treat symptoms that could otherwise be unpredictable. 

Possible ways to manage IBS symptoms are: 

• Receive comprehensive nutrition counseling from an IBS dietitian. 
• Try the low FODMAP approach. 
• Try a probiotic supplement created for IBS management. 
• Complete exercise regularly, such as walking, jogging, swimming, or dancing. 
• Relieve pain by taking peppermint oil or antispasmodic medication (prescription required). 
• Decrease stress levels through yoga, meditation, or mental health counseling. 

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Takeaway

There’s no denying it—a colonoscopy can feel invasive.

Still, it provides valuable insight into your digestive health and can identify possible tumors, cancers, and swollen tissues. 

However, a colonoscopy can’t diagnose IBS.

To get a diagnosis, your doctor may discuss your symptoms with you in-depth and then suggest tests to rule out other possible digestive disorders. 

By working with your IBS provider, you can create a treatment plan that targets your symptoms and helps you feel better. 

How a Dietitian Can Help

An IBS dietitian can help you manage IBS symptoms through diet and lifestyle changes.

You may not know what to expect if you’ve never met with a dietitian before. Here are questions to ask: 

• Can I test for IBS at home?
• Should I try an anti-inflammatory diet for IBS?
• How can I relieve IBS pain instantly?
• What’s the best probiotic for IBS? 

Find a dietitian who accepts insurance through Nourish to understand the link between nutrition and IBS management.