Ulcerative Colitis

What Is Ulcerative Colitis?

Ulcerative colitis (UC) is a chronic type of inflammatory bowel disease affecting the innermost lining of the colon (large intestine) and rectum. This condition causes inflammation, ulcers (sores), and irritation in the digestive tract, leading to abdominal pain, bloody diarrhoea, and cramping. Ulcerative colitis is marked by periods of exacerbation and remission, meaning that symptoms can flare up and then subside, often unpredictably.

Types of Ulcerative Colitis

Ulcerative colitis can be classified into several types according to the location and extent of the inflammation in the colon and rectum. These include:

Ulcerative Proctitis

This is characterised by inflammation confined to the anus or rectum. It is the mildest form of UC and typically presents with symptoms, such as rectal bleeding.

Left-Sided Colitis

This type involves inflammation that extends from the rectum up through the last section of the colon (distal colon), which includes the sigmoid and descending colon.


This type of UC affects the rectum and the lower end of the colon (sigmoid colon).


This is a severe type of UC that causes inflammation and ulcers in the entire colon.

What Are the Risk Factors for Ulcerative Colitis?

Several factors may increase the likelihood of developing ulcerative colitis, including:

Family History

Individuals with one or more first-degree relatives (parent, sibling, or child) who have the condition are more likely to develop it themselves.


While ulcerative colitis can occur at any age, it is more often diagnosed in individuals between the ages of 15 and 30 or over 60.

Immune System Malfunction

Ulcerative colitis may occur due to an abnormal immune response that causes the body's defence mechanism to mistakenly target its own digestive tract cells.

Signs and Symptoms of Ulcerative Colitis

Individuals with ulcerative colitis may exhibit a wide range of symptoms, such as:

Abdominal Pain and Cramping

The pain is usually felt in the lower abdomen and can range from mild discomfort to severe cramping.

Blood and Pus in Stool

Patients often experience stools that contain blood and pus due to infection and ulceration in the colon lining.


This is characterised by loose or watery stools often accompanied by blood or pus, which indicates that the colon is inflamed.


During severe flare-ups, some individuals may experience a fever, indicating the body's response to inflammation.

Weight Loss

The inflammation in the intestines can affect the body's ability to absorb nutrients, leading to significant weight loss.


This refers to a sensation of incomplete bowel emptying and the persistent urge to have a bowel movement.


This is characterised by a constant feeling of extreme tiredness that can result in nutritional deficiencies and anaemia.

How Is Ulcerative Colitis Diagnosed?

To diagnose ulcerative colitis, the doctor will conduct a physical examination and ask about the patient’s symptoms and family history of Inflammatory Bowel Disease (IBD). They will also perform additional tests, such as:

Blood Test

This test checks for signs of a low red blood cell count (anaemia) or infection.

Imaging Scans

Computerised tomography (CT) and magnetic resonance imaging (MRI) scans can generate images of the colon and rectum to assess the extent of inflammation.

Stool Sample

This test analyses the patient’s faecal matter to identify inflammatory markers, as well as the presence of bacteria and parasites. It also checks for white blood cells or certain proteins that may indicate ulcerative colitis.


This procedure examines the entire colon using a thin, flexible tube called a colonoscope. Tissue samples (biopsies) may also be taken during a colonoscopy to confirm the extent of inflammation, ulcers, or abnormal cells.

Flexible Sigmoidoscopy

In this procedure, the doctor employs a flexible tube to inspect the lower part of the colon, including the rectum and sigmoid colon. They may also extract a sample from the lower colon lining for laboratory analysis.

Treatments for Ulcerative Colitis

Treatment options for ulcerative colitis vary based on its severity and type. These include:


To alleviate inflammation and manage symptoms, the doctor may prescribe anti-inflammatory drugs, corticosteroids, and immune system suppressors. In some cases, biologics may be recommended to target specific proteins within the immune system.

Lifestyle and Dietary Changes

It is advisable to avoid trigger foods, such as spicy foods, alcohol, and caffeine. Instead, maintain a healthy diet rich in fruits and vegetables. In addition, regular exercise and stress management techniques may help to improve symptoms.


This is the last resort for patients with severe ulcerative colitis. The most common surgical procedure is a proctocolectomy, in which the surgeon removes all or part of the colon and rectum.

Complications of Ulcerative Colitis

Ulcerative colitis can result in various complications if not properly treated. These include:


An inflamed and damaged colon may impair nutrient absorption, leading to deficiencies in essential vitamins and minerals, weight loss, and weakened immune function.

Bowel Obstruction

This occurs when inflammation and scarring cause the intestines to become blocked, leading to severe abdominal pain, bloating, and the inability to pass stool or gas.


Chronic inflammation and prolonged use of corticosteroids can lead to decreased bone density, making individuals with UC susceptible to fractures and osteoporosis.


Persistent bleeding within the gastrointestinal tract may lead to anaemia or a low red blood cell count.


This occurs when there is a hole in the colon wall, leading to leakage of intestinal contents into the abdominal cavity.

Severe Dehydration

Chronic diarrhoea and inflamed intestinal tissues can hinder proper fluid absorption, resulting in severe dehydration.

Toxic Megacolon

Severe ulcerative colitis can cause abnormalities in the colon. When this happens, the substances inside the colon start to build up and cause the colon walls to swell or burst while toxins leak into the bloodstream.

Blood Clots

Ulcerative colitis may cause blood clots to form in the veins, arteries, and capillaries, causing life-threatening conditions such as pulmonary embolism.

Increased Risk of Colon Cancer

Individuals who have had ulcerative colitis for an extended period are at an increased risk of developing colon cancer.

Frequently Asked Questions (FAQs)

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Meet Our Specialist

Dr Kieron Lim

MBBS, University of LondonMember, Royal College of Physicians (UK)Fellow, Academy of Medicine (Gastroenterology) SingaporeFellow, Royal College of Physicians (Edinburgh)

Dr Kieron Lim is a senior consultant specialising in gastroenterology and hepatology. He has over 20 years of specialist experience providing evidence-based care for patients with all types of gastrointestinal conditions, including ulcerative colitis. Dr Lim is skilled in wide range of endoscopic procedures and medical management of complex gastrointestinal cases in order to improve the quality of life for his patients.