Diagnosis of Ulcerative Colitis

How do doctors diagnose ulcerative colitis?

To diagnose ulcerative colitis, doctors review medical and family history, perform a physical exam, and order medical tests. Doctors order tests to

  • confirm the diagnosis of ulcerative colitis
  • find out how severe ulcerative colitis is and how much of the large intestine is affected
  • rule out other health problems—such as infections, irritable bowel syndrome, or Crohn's disease—that may cause symptoms similar to those of ulcerative colitis

Medical and family history

To help diagnose ulcerative colitis, your doctor will ask about your symptoms, your medical history, and any medicines you take. Your doctor will also ask about lifestyle factors, such as smoking, and about your family medical history.

Doctor talking with a patient.
Your doctor will ask about your symptoms, medical history, and family medical history.

Physical exam

During a physical exam, your doctor may

  • check your blood pressure, heart rate, and temperature—if you have ulcerative colitis, doctors may use these measures, along with information about your symptoms and test results, to find out how severe the disease is
  • use a stethoscope to listen to sounds within your abdomen
  • press on your abdomen to feel for tenderness or masses

The physical exam may also include a digital rectal exam to check for blood in your stool.

What tests do doctors use to diagnose ulcerative colitis?

Doctors may use blood tests, stool tests, and endoscopy of the large intestine to diagnose ulcerative colitis.

Blood tests

A health care professional will take a blood sample from you and send the sample to a lab. Doctors use blood tests to check for signs of ulcerative colitis and complications, such as anemia. Blood tests can also show signs of infection or other digestive diseases.

Stool tests

A health care professional will give you a container for catching and storing the stool. You will receive instructions on where to send or take the container for analysis. Doctors may use stool tests to check for conditions other than ulcerative colitis, such as infections that could be causing your symptoms. Doctors may also use stool tests to check for signs of inflammation in the intestines.

Endoscopy of the large intestine

Doctors order endoscopy of the large intestine with biopsies to diagnose ulcerative colitis and rule out other digestive conditions. Doctors also use endoscopy to find out how severe ulcerative colitis is and how much of the large intestine is affected.

During an endoscopy, doctors use an endoscope—a long, flexible, narrow tube with a light and a tiny camera on one end—to view the lining of the large intestine. Doctors obtain biopsies by passing an instrument through the endoscope to take small pieces of tissue from the lining of your rectum and colon. A pathologist will examine the tissue under a microscope.

Two types of endoscopy used to diagnose ulcerative colitis are

Last Reviewed September 2020
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This content is provided as a service of the National Institute of Diabetes and Digestive and Kidney Diseases (NIDDK), part of the National Institutes of Health. NIDDK translates and disseminates research findings to increase knowledge and understanding about health and disease among patients, health professionals, and the public. Content produced by NIDDK is carefully reviewed by NIDDK scientists and other experts.