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Tests for Crohn’s Disease & Colonoscopy

Tests for Crohn’s Disease & Colonoscopy?noresize

Crohn’s Disease affects the entire digestive system, but most often presents in the ileum, the end of the small intestine. The rest of the small intestine, large intestine, and colon may also be affected by this inflammatory bowel disease.

Crohn’s symptoms include stomach pain, diarrhea, and bloody stool. While these symptoms, among others, indicate you may have Crohn’s, there is no single test to diagnose Crohn’s disease. Instead, your doctor will likely use a variety of blood tests, stool tests, imaging tests, colonoscopy, and/or tissue biopsies to identify if Crohn’s is present.

Initial Exam

The first step in diagnosing Crohn’s is gathering your history and completing a physical examination. Your doctor will discuss your symptoms, your health history, and your family’s medical history. Some symptoms your doctor will likely ask about include:

  • Stomach pain or cramping
  • Diarrhea
  • Bloody stool
  • Urgent bowel movements
  • Fatigue
  • Fever
  • Lack of appetite
  • Sores in your mouth or around your anus
  • Weight loss

After your doctor has more information, she will order tests to help rule out other medical conditions that have similar symptoms to diagnose Crohn’s Disease.

Lab Tests

Your doctor will likely recommend a blood test as part of the diagnostic process. This test will show if you have any infection or inflammatory markers in your blood. Elevated white blood cells or platelets point to infection or inflammation, which may be related to Crohn’s Disease or another inflammatory condition.

A blood test will also identify anemia, or low red blood cells, which may also be related to Crohn’s or another condition. While a blood test alone cannot diagnose Crohn’s, it can point your doctor in the right direction.

Your doctor may also order a stool test. A stool test will identify any blood in your stool, which may indicate Crohn’s Disease. A stool test will also identify any disease-causing organisms in your stool, which would point to a different gastrointestinal problem such as a bacterial or parasitic infection, not Crohn’s Disease.

Imaging Tests

X-rays, MRI scans, CT scans, and upper gastrointestinal series tests all allow your doctor to identify inflammation or damage from the outside. If Crohn’s disease is suspected, your doctor will likely order one, or multiple, of these tests to look at your small intestine.

  • X-rays show narrowing or widening of the intestines, as well as any perforations or blockages present. These images are useful for ruling out complications related to Crohn’s Disease.
  • MRI scans use radio waves and magnets to create an image of the body and help your doctor identify inflammation or narrowing within the digestive tract.
  • CT scans are cross-sectional X-rays, which help identify blockages, abscesses, infection, or fistulas. CT scans also check for potential complications and help rule out conditions other than Crohn’s that present similar symptoms.
  • Upper gastrointestinal series tests are used to create a complete picture of your small intestine, stomach, and large intestine. Doctors use imaging series tests to identify any abnormalities in the gastrointestinal system that may signal Crohn’s Disease.


Colonoscopies are the most important tool for diagnosing Crohn’s Disease. A colonoscopy uses an endoscope, a thin, flexible tube with a camera at the end to examine the colon. Endoscopes are also used in other procedures to examine different parts of the upper and lower gastrointestinal tract. A colonoscopy examines the entire colon, a sigmoidoscopy specifically examines the end of the colon, and an upper endoscopy examines the esophagus, stomach, and beginning of the small intestine.

Doctors use colonoscopies to identify damage in the colon, including inflammation, ulcers, or bleeding. One example of potential damage is a granuloma, a small grouping of cells that indicate Crohn’s Disease in the colon.

As a less invasive option, your doctor may order a capsule endoscopy. This test requires swallowing a small capsule with a camera inside. The camera creates images of the inside of your digestive tract, which your doctor will use to look for Crohn’s signs. While a capsule endoscopy is less invasive, it does not allow your doctor to collect tissue samples during the test in the way a traditional colonoscopy does.

Tissue Biopsy

During a colonoscopy, your doctor may collect small digestive tissue samples. This process is known as a biopsy and helps identify inflamed areas or abnormal cells in the colon. After removal, the tissue is sent to a lab to be analyzed for inflammation or other potential problems linked to Crohn’s.

Diagnosing Crohn’s

Your doctor will use the results from a combination of the tests above to conclude whether you have Crohn’s disease. Although there is no single test for this condition, using various tests paints a clear picture of your digestive condition and allows your doctor to make a diagnosis.

After an accurate diagnosis is made you and your doctor will work together to develop a treatment plan.

Our team of nutritionists and dietitians are here to help you navigate the nutrition aspects of Crohn’s disease and help prevent future flares.

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