Chronic diarrhea, weight loss, and abdominal pain are all symptoms of ulcerative colitis, which causes ulcers to form in the large intestine or rectum.

Ulcerative colitis (UC) is an autoimmune condition that affects the digestive system. It is a form of inflammatory bowel disease, which affected about 3 million adults in the United States in 2015.

While experts are not entirely sure what causes UC, they know that it involves the immune system mistaking healthy cells for unhealthy ones.

A doctor uses a colonoscopy to examine the inside of the colon, which is also called the large intestine. This helps them diagnose UC, check the severity, and see how well treatment is working. Because people with UC have an increased risk of colorectal cancer, doctors also use this test to screen for cancer regularly.

In this article, learn more about the purpose of a colonoscopy, how often someone with UC needs one, and how to prepare for it.

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A colonoscopy is a test that can help a doctor diagnose UC, including how severe it is and how much of the colon is affected. The doctor also uses it to screen for colorectal cancer.

To examine the inside of the large intestine and rectum, a doctor uses a colonoscope — a thin, flexible tube with a small camera and a light.

During the test, the doctor looks for signs of inflammation, ulcers, and any other abnormalities. They also check for precancerous growths called polyps.

A colonoscopy is a minor procedure, but many people find it useful to know what to expect.

Before the procedure

A person needs to drink preparation beverages to clear out their colon, and they also need to fast. The doctor will provide specific instructions ahead of time.

During the procedure

First, the person receives a sedative to help them relax and reduce discomfort. Then, they lie on one side and the doctor inserts the colonoscope through their anus and into their rectum and colon.

On a monitor, the doctor examines the images that the scope sends back. They can also use the colonoscope to remove any polyps and take a biopsy. This involves removing a small piece of tissue and sending it to a lab, which tests the sample for cancer and other abnormalities.

After the procedure

It can take 1–2 hours for the sedative to wear off, and the person should not drive home.

Also, they may experience cramping, bloating, and general abdominal discomfort, although this should resolve by the next day.

There are three reasons that a person with UC needs a colonoscopy. The first is to diagnose the condition, the second is to check how well treatments are working, and the third is to screen for colorectal cancer.


If a person has symptoms of UC, a doctor may recommend a colonoscopy to diagnose the condition.

During a colonoscopy, doctors can identify characteristic areas of damage, swelling, inflammation, and sores in the intestine. They can also determine the severity of UC and see how much of the colon is affected.

Learn more about how doctors diagnose UC.


After diagnosing UC, the doctor prescribes treatment, usually medication. The aim is to reduce inflammation and heal the colon.

There is no cure for UC. It is essential to manage the condition and support overall health, and regular colonoscopies are part of this process.

Doctors use this test to monitor the inflammation and condition of the intestinal lining and to see how well the current treatment plan is working and whether it needs adjusting.


Healthcare professionals use colonoscopies to screen people with UC for colorectal cancer. Even people whose UC is in remission have a higher risk of colorectal cancer than people without UC.

Because people with UC have an increased risk of colorectal cancer, they should have regular colonoscopies.

The Crohn’s and Colitis Foundation recommend that people who have had UC symptoms for at least 8 years get a colonoscopy every 1–2 years. But a person’s doctor will provide the most appropriate guidance.

Even if a person’s UC is under control, colonoscopies are still crucial. They can identify precancerous cells and cancer early, when treatment is easier. Colorectal cancer is very treatable when caught early.

Learn more about colorectal cancer.

A colonoscopy requires some preparation, and the doctor will provide specific instructions for each person in the weeks leading up to the procedure.

The preparation may involve:

  • limiting the intake of raw fruits, vegetables, nuts, and other foods that leave residue in the stool
  • consuming only clear liquids 24 hours before the colonoscopy
  • drinking a liquid solution that clears out the colon — usually half in the evening before the colonoscopy and the other half 4–6 hours beforehand
  • wearing loose, comfortable clothing and staying near a bathroom

Anyone who has questions about how to prepare should ask a healthcare professional.

Other methods can help doctors diagnose UC. They may order the following tests:

  • Laboratory tests of blood and stool samples: Doctors look for blood biomarkers of inflammation, including C-reactive protein and the erythrocyte sedimentation rate. They also look for biomarkers of inflammation in stool.
  • Diagnostic imaging: A colonoscopy cannot send images of the entire colon, so doctors use radiology to check hard-to-access areas. Radiology tests may include X-rays, CT scans, and contrast studies.
  • Upper endoscopy: An endoscopy involves sending a small camera attached to a scope through the mouth and down into the small intestine. A person can also swallow a pill-sized camera that records images as it travels through the intestinal tract.

UC is a chronic condition and currently has no cure. This means that people with UC need to manage it throughout their lives.

The severity of UC varies from person to person. A doctor prescribes medication to manage a person’s symptoms and help support the quality of life. They may also recommend other strategies, such as dietary changes.

Having a UC diagnosis may feel overwhelming, but many approaches to treatment can lessen the impact of the condition. Be sure to discuss the range of options, as well as any concerns or changes with the doctor.

Learn more about treatments for UC.

A colonoscopy is an examination of the inside of the rectum and large intestine. Doctors use this procedure to help them diagnose UC, a form of inflammatory bowel disease.

A person with UC needs regular colonoscopies so that the doctor can tell whether the treatment plan is effective. Also, people with UC have an increased risk of colorectal cancer, and doctors use colonoscopies to screen for cancerous cells.

The Crohn’s and Colitis Foundation recommend that people who have had UC symptoms for at least 8 years get a colonoscopy every 1–2 years. But a doctor will recommend a tailored schedule for each person.