Ulcerative colitis is a long-term condition that affects the large intestine. It causes the lining of the colon to swell, which leads to open sores and ulcers. Ulcerative colitis is a type of inflammatory bowel disease (IBD).

Diagnostic tests for ulcerative colitis can include blood tests, stool tests, and colonoscopies. Doctors may begin by asking the person questions about their family history and symptoms.

This article explains how doctors diagnose ulcerative colitis and what a person can expect during this process. It also includes firsthand stories from Daisy Warner, who received a diagnosis of ulcerative colitis in 2012 and is now in remission.

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To diagnose ulcerative colitis, doctors ask several questions and carry out a range of tests. The sections below look at some of these tests in more detail.

Family and medical history

The doctor may ask a person about the following subjects.

SubjectsPossible questions
SymptomsWhat are they?
When do they happen?
How long have you had them?
How long do they typically last?
Family historyHas anyone in your family ever had IBD or another health condition?
MedicationsAre you currently taking any medications?
If so, what are they?
LifestyleDo you smoke?
Do you drink any alcohol?
If so, how much?

Some typical symptoms of ulcerative colitis may include:

Learn more about ulcerative colitis symptoms here.

Daisy’s story: Symptoms and medical history

“I was 16 years old when I first noticed symptoms that I later found out were due to ulcerative colitis. The first symptom I noticed was severe fatigue, but I put this down to the exams I was taking at the time. I was also noticing abdominal pain [and] more frequent bowel movements, and I was also passing blood. I noticed mucus in my stools and was experiencing frequent bouts of diarrhea.

At first, doctors thought that my symptoms were happening because of hemorrhoids, a stomach bug, parasite, or possibly a small tear. As my exams finished and my stress levels decreased, my symptoms became less noticeable too. However, they still persisted, and I was admitted to the hospital when I began to lose weight after not being able to eat [or] drink.

When the doctors asked my mother and me about my family history, we explained that bowel cancer had affected some family members in the past. The doctors then ordered some blood and stool tests to investigate further.”

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Physical examination

A physical examination can involve:

  • checking the person’s blood pressure, temperature, and heart rate
  • listening to the person’s stomach with a stethoscope
  • checking for tenderness or lumps by pressing on the person’s stomach

Sometimes, the doctor may also carry out a digital rectal examination. This means gently inserting a lubricated finger into the rectum to check for signs of ulcerative colitis.

Blood tests

During a blood test, a healthcare professional uses a needle to remove a small amount of blood from the person’s arm. They then send this sample to a laboratory, where a scientist looks for signs of ulcerative colitis, including evidence of infection, anemia, or inflammation.

Daisy’s story: Blood tests

“My symptoms worsened as I went through various tests to work out their cause. One of the first tests was a blood test, which doctors ordered when they believed my symptoms were happening due to a parasite. When the results came back, the doctors told me I had clear signs of inflammation.

I began taking some medications to ease my symptoms, and after these blood test results came back, the doctors referred me for further tests.”

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Stool tests

To perform a stool test, a doctor or nurse gives the person a container and asks them to deposit a small amount of stool into it. A scientist then analyzes the stool for signs of ulcerative colitis.

Endoscopy and colonoscopy

An endoscope is a long, flexible tube with a tiny camera and a light on the end. When a doctor uses this tool to look inside the large intestine, the procedure is known as colonoscopy.

A healthcare professional usually asks the person to prepare their bowel for this procedure. For example, they may recommend that they follow a clear liquid diet for 1–3 days beforehand. Alternatively, they may prescribe a combination of laxatives. This will cause diarrhea to ensure that the bowel is clear before the procedure.

Colonoscopy takes 30–60 minutes. The healthcare professional usually administers sedatives or pain medications and asks the person to lie on their side. They then insert the tube through the anus, into the rectum, and then into the colon.

Learn how to prepare for a colonoscopy here.


Doctors may also use the endoscope to take a biopsy during this procedure. This means removing parts of the colon lining and checking them under a microscope for signs of ulcerative colitis.

Daisy’s story: Colonoscopy

“After my blood test, doctors referred me for a colonoscopy and biopsy. I was very nervous for this procedure, but I would urge people not to put it off, as it can be so helpful for making a diagnosis.

The results from my own colonoscopy came back inconclusive because my ulcerative colitis seemed to affect a slightly different part of the bowel. However, based on what the doctors saw during this test, along with my blood test results and symptoms, I finally received a diagnosis of severe left sided ulcerative colitis about 2–3 months after my symptoms began.”

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There is currently no cure for ulcerative colitis. Doctors usually recommend a combination of treatments to help reduce the inflammation and ease the symptoms. It is important to remember that treatment can vary from person to person.

The sections below look at some treatment options in more detail.


Some medications that can help treat ulcerative colitis include:

Lifestyle changes

According to the National Institute of Diabetes and Digestive and Kidney Diseases, people with ulcerative colitis should try to eat a healthy, well-balanced diet. Some foods can make ulcerative colitis worse, but these foods can vary from person to person.

Many people with ulcerative colitis find that it helps to keep a food diary so that they can identify which foods affect their symptoms and subsequently avoid them.

Learn about foods to eat and avoid with ulcerative colitis here.


If medications and lifestyle changes do not work, doctors may suggest surgery. The two main types of surgery for ulcerative colitis are:

  • Ileoanal reservoir surgery: Surgeons remove the colon and the rectum, then use the end of the small intestine to make a pouch. They then attach the pouch to the anus. After the operation, stool collects in the pouch and passes through the anus.
  • Ileostomy: Surgeons remove the colon and the rectum, then attach the end of the small intestine to an opening in the abdomen. Doctors call this opening a stoma. After the operation, stool passes through the stoma into an ostomy pouch, which is a bag that the person wears on the outside of the body.

Learn more about treatment options for ulcerative colitis here.

Daisy’s story: Treatment first steps

“Once I had received a diagnosis, doctors suggested [that] I try enemas and taking medications such as oral steroids. These can be very effective for ulcerative colitis, but, at first, I did not notice much of a change in my symptoms. However, as I understood the condition better, I realized the most powerful treatment was actually to combine the medication with lifestyle changes.

I researched different diets to try and kept a food diary to understand which foods caused my symptoms to worsen. I found information on the specific carbohydrate diet and gradually removed gluten and dairy from my diet as I identified them as trigger foods.

I did find that some dietary changes improved symptoms at first and then worsened them over time. This is why it was very important that I followed diets strictly and worked with doctors to understand the best course of treatment for me.”

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The specific carbohydrate diet involves cutting out foods that contain disaccharides and most polysaccharides, such as grains, milk products, and most sugars. A person can include foods that contain monosaccharides, such as fruits, nuts, non-starchy vegetables, meat, and fish.

Step therapy

Health insurance companies sometimes use a protocol called step therapy for people with a diagnosis of ulcerative colitis. This aims to provide people with cheaper alternatives to medications that a doctor has recommended before trying more expensive options if these more affordable drugs do not work.

In a 2016 survey involving 2,600 people with IBD, 40% of them had undergone step therapy. Of these, 59% stated that they were unable to start their recommended treatment plan within 3 months because of this.

Knowing about step therapy is crucial to understanding how to reform it. The Crohn’s and Colitis Foundation suggests that people work closely with their healthcare team and insurance company to navigate appeals to this process.

A person can also join the Crohn’s and Colitis Foundation Advocacy Network to support transparent appeals and clear timelines.

Clinical trials

A doctor may mention clinical trials when discussing treatment options for ulcerative colitis. Clinical trials can involve taking part in a study that looks at the effect of certain treatment options that might not be widely available.

One such option for ulcerative colitis is a fecal transplant. Learn more about fecal transplants for ulcerative colitis here.

A doctor should inform the person of any risks involved to help them decide whether or not to take part.

Learn more about clinical trials for ulcerative colitis here.

The diagnostic process for ulcerative colitis can be a challenging experience. However, there are several tips that may make this process easier.

Daisy’s story: Tips for others

  • Stay informed: “Online resources from reputable sources can help a person understand ulcerative colitis better. It can help them prepare for test[s] and appointments and may give them ideas of important questions to ask a doctor.”
  • Be open: “Maintaining an honest and open line of communication with a doctor can speed up the diagnostic process. Do not dismiss the idea of lifestyle changes, which can make an enormous difference to symptoms, but be sure to follow the treatment advice [that] doctors have given. Equally, make sure to tell a doctor in detail if a treatment does not seem to be working.”
  • Feel empowered: “People should remember that their health condition does not define them. Some people find discussing bowel habits and colonoscopies embarrassing, and I definitely relate to that. However, it is important to remember that these are natural bodily processes and tests, and being open and honest can make a huge difference in managing symptoms successfully. It is important to make an invisible condition visible in this way.”
  • Stay mindful: “Stress has always been a trigger for my symptoms, and the diagnosis process alone can be stressful. Try to make mindful activities [— such as yoga, meditation, or some physical exercise —] part of the daily routine. This can help people learn to manage symptoms even after a flare-up has passed.”
  • Seek support: “Several great support groups exist for people with ulcerative colitis. It can be helpful to know [that] you are not alone and to learn more about current research and topics within this community.”
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Find a support group through the Crohn’s and Colitis Foundation here.

Ulcerative colitis is a long-term condition that affects the large intestine. A fault in the immune system causes it.

Doctors carry out several tests to diagnose ulcerative colitis. These might include blood and stool tests, physical examinations, and endoscopies.

There is currently no cure for ulcerative colitis, but people can try dietary changes, lifestyle changes, and certain medications to manage their symptoms. That said, some people may need an operation to remove their colon and rectum.

The process of seeking and receiving a diagnosis of ulcerative colitis can be challenging. It may help to listen to how other people have overcome the challenges of living with the condition.