Ulcerative colitis (UC) causes inflammation and ulcers to develop on the colon’s lining. Doctors use colonoscopies and imaging techniques such as CT and MRI scans to diagnose UC. X-rays may also help detect differences in the colon if other modalities are unavailable.

UC is a form of inflammatory bowel disease (IBD) affecting the colon and rectum. It typically manifests in 9–20 people per 100,000 per year. Although there is no known cause, medical professionals believe genetics and environmental factors play a significant part in people developing the condition.

Medical professionals use different imaging modalities. X-rays are not the first line. However, they can be helpful in emergent situations when other modalities are not readily available or safe.

This article explores how doctors diagnose UC and its symptoms, causes, and treatment.

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Diagnostic imaging can help determine the extent and severity of the inflammation and assess any potential disease complications. This information will allow a gastroenterologist to recommend the best course
of treatment for a person’s condition.

The main diagnostic tool for UC is a colonoscopy. In addition to this, there are different imaging techniques, including:

  • colonoscopy
  • blood and stool tests
  • CT scans
  • MRI scans
  • plain radiographs

Colonoscopy and endoscopy are preferred and recommended by doctors for diagnosing and monitoring UC.

A colonoscopy uses a flexible tube with a camera to look inside a person’s rectum or colon. A person will usually receive some sedation during the procedure and must ensure their bowels are empty before the procedure.

The procedure usually takes around 30–60 minutes. During this time, the colonoscope may also inflate the large intestine with air for a better view. Gastroenterologists may also take a biopsy sample during a colonoscopy.

Another option is a virtual colonoscopy, which uses X-rays and does not view the entire colon. It takes less time and does not require an anesthetic.

Doctors recommend people with UC have regular colonoscopies due to the risk of colon cancer. At least 5% of people with UC may develop colon cancer. This risk increases with the duration and levels of disease activity.

Blood and stool tests are usually second-line studies that doctors undertake in diagnosing a person.

Blood and stool samples can show signs of UC and possible complications, such as anemia. They can also help identify infections and other associated digestive diseases.

Stool samples can also show signs of inflammation in the intestines.

Read more about the diagnosis of UC.

During a CT scan, a person lies on a bed that slowly moves through a cylinder-shaped structure while an X-ray tube rotates around the person.

CT scans use digital X-ray detectors instead of traditional film detectors to create a clearer image of a person’s internal structure and how much of a person’s colon is inflamed.

Doctors do consider radiation a risk factor for cancer. CT scans produce the largest amount of radiation compared to other types of scans.

An MRI is a noninvasive imaging procedure that uses magnetic fields and radio waves to produce a detailed image of the inside of a person’s body.

An MRI scanner is a large tube in which a person lies while a radiographer monitors the scanner. It can last for 15–90 minutes.

Other diagnostic tools such as plain radiograph and barium fluoroscopy do exist. However, they are fairly outdated in comparison to the other techniques.

Plain radiograph

Plain radiographs are a very old approach to diagnosing UC, and doctors will often not use this method unless other techniques are not available.

Medical radiography is a form of X-ray. This method records images of the body’s internal structure to assess disease activity and structural damage or differences.

Plain radiographs can show the colon wall thickening or mural thickening, often caused by inflammatory diseases such as UC. This 2018 study recommends a person undergoes an endoscopy following a CT scan that shows mural thickening as a surveillance method.

However, a plain radiograph is a fairly outdated approach to diagnosing UC and is limited compared to CT or MRI scans. Although in emergency situations this method is useful to evaluate the colon for severe inflammation and, more importantly, if there are signs that suggest colon perforation.


Compared to the images produced by CT and MRI, barium fluoroscopy has much less resolution and is much less common nowadays.

Fluoroscopy uses barium to view the gastrointestinal tract under X-ray imaging. Barium is a chalky and milky liquid that a person will drink before the procedure.

A specialist passes the X-ray beam through the body during a fluoroscopy procedure. The X-ray transmits the image to a monitor so that the radiologist cans see the inflamed area in detail.

When using this form of X-ray, symptoms can show in various ways:

  • inflammation on the surface of the bowel can appear as a granular texture
  • ulcers can appear as button-shaped mounds
  • in chronic cases, the bowel becomes featureless and becomes sorter with a lead pipe appearance
  • residual mucus can form to have worm-like appearances

UC is a long-term condition that causes inflammation and ulcers in the colon and rectum.

Medical professionals can use different imaging techniques to diagnose the condition. The most common modalities are colonoscopies, blood and stool tests, and imaging procedures such as CT and MRI scans.

In some rare cases, a doctor may use X-rays or barium fluoroscopy if the above options are unavailable. However, these techniques are fairly outdated compared to advanced diagnostic tools.