How is inflammatory bowel disease diagnosed?

Reviewed by: HU Medical Review Board | Last Reviewed: December 2017.

Inflammatory bowel disease (IBD) can cause a variety of symptoms, and the symptoms vary by individual. In cases of Crohn’s disease (CD), the inflammation inside of the digestive tract can cause symptoms spanning the mouth to the anus, and some patients have inflammation that occurs outside of the digestive tract, which can cause other symptoms affecting other areas and functions of the body. In cases of ulcerative colitis (UC), the inflammation can affect some or all of the large intestine. In addition to digestive symptoms, people with UC may also experience symptoms affecting other parts of the body. Symptoms of IBD may come and go as the disease goes through periods of flares and periods of remission.1,2

Common symptoms of IBD are:1-3

If a patient is experiencing symptoms that might be caused by IBD, then a healthcare provider will take steps to find out if the symptoms are actually being caused by IBD or if they are the result of some other condition or cause. The following conditions can cause symptoms that are similar to the symptoms of IBD:2

  • Stomach flu (gastroenteritis)
  • Traveller’s diarrhea
  • Celiac disease
  • Gallbladder disease
  • Pancreatitis
  • Lactose intolerance
  • Stomach ulcers
  • Irritable bowel syndrome
  • Colorectal cancer

There is no single test that can be used to diagnose IBD directly. This means that the process of finding out if a patient’s symptoms are being caused by IBD involves several steps, many of which are focused on ruling out other causes for the symptoms. Typically, the process of diagnosing IBD will include:2,3

  • Taking the patient’s medical history
  • Performing a physical examination
  • Laboratory testing of the patient’s blood and stool
  • Diagnostic procedures called “endoscopy”
  • Diagnostic imaging and scanning

What happens when the healthcare provider takes a medical history?

A first step in diagnosing IBD is taking the patient’s medical history.3,4 The healthcare provider will ask questions about the patient’s symptoms, such as:

  • What kinds of symptoms the patient has been having
  • Where in the body the symptoms are located
  • When the symptoms started
  • How severe the symptoms are
  • What tends to make the symptoms better or worse
  • Whether there is a pattern to the symptoms, such as the frequency and consistency of bowel movements
  • How the symptoms affect the patient’s life, such as causing absences from school or work

The healthcare provider will learn about the patient’s health history and find out if there are any other members of the patient’s family who have IBD. People who have an immediate family member with IBD are more likely to develop IBD themselves; however, most people with IBD do not have a family member with the disease.

Because many of the symptoms of IBD can also have various other kinds of causes, the healthcare provider may also ask questions about whether the patient:

  • Has travelled recently
  • Has taken antibiotics or other medications recently
  • Has any food intolerances
  • Is a current or former smoker

What happens during the physical examination for inflammatory bowel disease?

During the physical examination, the healthcare provider checks the patient’s heart rate, blood pressure, temperature and body weight.3,5 The provider also examines and listens to the patient’s abdomen to check for tenderness and swelling.

Many people with IBD have symptoms in the rectum or anus that are caused by perianal disease. To check for signs of perianal disease, the healthcare provider will usually perform a rectal examination. Symptoms of perianal disease include:

  • Areas of inflammation and collected pus (an abscess)
  • Tunnels that have developed around the anus (a fistula)
  • Tear or split around the anal canal (an anal fissure)
  • Narrow skin growths (skin tags)
  • Narrowing of the digestive tract (a stricture)
  • Hemorrhoids

What types of laboratory tests can be used to help diagnose inflammatory bowel disease?

After the taking the patient’s medical history and performing the physical examination, the healthcare provider may ask the patient to provide small samples of blood and stool for further testing.3,4,6 These tests can be used to help detect whether there is inflammation or infection present in a person’s body that may be caused by IBD. They can also be used to help find out if the inflammation or infection is the result of some cause other than IBD.

What kinds of procedures are used to help diagnose inflammatory bowel disease?

Healthcare providers may recommend further diagnostic procedures based on the results of the patient’s medical history, physical examination, and laboratory tests.2-4 Although a patient’s symptoms and the results of laboratory tests can aid in the diagnosis of IBD, diagnostic procedures are needed to detect more specific signs of the disease inside a patient’s digestive tract.

Endoscopy procedures allow a healthcare provider to look inside a patient’s digestive tract using a tiny camera and light that are attached to a very thin, flexible tube inserted into the body. The most common type of endoscopic procedure used to diagnose IBD is colonoscopy.

Diagnostic imaging and scanning use technology to capture an image or some other kind of representation of the inside of a person’s body. For people who may have IBD, these techniques can be used to analyze parts of the body outside of the digestive tract, as well as parts of the digestive tract that cannot usually be reached by endoscopy procedures.

How do doctors determine if it's Crohn's disease or ulcerative colitis?

While the symptoms of CD and UC are similar, the two diseases have different ways of affecting the digestive tract. In Crohn's disease, the inflammation may occur at any point along the digestive tract, from the mouth to the anus. In ulcerative colitis, the inflammation occurs in the large intestine, and the disease may affect portions of the large intestine or the entire length of the large intestine. The inflammation in UC only affects the innermost layer of the intestine, where the inflammation caused by CD can penetrate the entire thickness of the intestinal wall.1

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