Colitis

Colitis is the medical term used to describe inflammation of the colon, also known as the large intestine. In Singapore, colitis is seen across a wide range of patients — from acute cases triggered by infection to chronic conditions involving the immune system. The colon plays an essential role in absorbing water, forming stool and maintaining the balance of bacteria within the gut. When its lining becomes inflamed, these functions are disrupted, leading to changes in bowel habits and abdominal discomfort.

Inflammation may develop suddenly or progress gradually over time. In some cases, it is short-lived and resolves with supportive care. In others, it is part of a long-term condition that requires ongoing medical management. The severity can range from mild irritation to extensive inflammation that causes bleeding and significant symptoms

What are the different types of colitis?

Colitis is not a single disease but a broad term that includes several different conditions. These vary in cause, duration and treatment approach. Some forms are temporary and resolve with supportive care, while others require ongoing medical management to control inflammation and prevent complications.

What causes colitis?

Colitis develops when the lining of the colon becomes inflamed. The underlying cause varies depending on the type of colitis and whether the inflammation is acute or chronic. In some cases, the trigger is temporary and resolves with treatment. In others, the condition reflects an ongoing immune or vascular problem that requires long-term management.

• Autoimmune conditions — in ulcerative colitis and Crohn’s disease, the immune system mistakenly attacks the bowel lining, leading to persistent inflammation.
• Infections — bacterial, viral or parasitic infections, often from contaminated food or water, can cause sudden inflammation of the colon.
• Reduced blood supply — ischaemic colitis develops when blood flow to part of the colon is restricted due to narrowed vessels, clots or low blood pressure.
• Medications — certain drugs, including some antibiotics and anti-inflammatory medicines, may irritate or disrupt the colon lining.
• Radiation therapy — radiation to the abdomen or pelvis can damage colon tissue and result in inflammation.
• Microscopic immune reactions — in microscopic colitis, inflammation is visible only under a microscope and may be linked to immune factors or medication exposure.

What are the common symptoms of colitis?

Symptoms of colitis vary depending on the cause and severity of inflammation, but most relate to changes in bowel habits and abdominal discomfort. Some symptoms develop suddenly, while others persist or recur over time.

• Persistent diarrhoea — frequent loose or watery stools due to inflammation affecting normal fluid absorption.
• Blood in the stool — visible or microscopic bleeding caused by irritation or ulceration of the colon lining.
• Abdominal pain or cramping — discomfort resulting from inflammation and increased bowel activity.
• Urgency to pass stool — a sudden and difficult-to-control need to open the bowels.
• Tenesmus — a persistent sensation of incomplete emptying after a bowel movement.
• Mucus in stool — excess mucus production from an inflamed intestinal lining.
• Fatigue — ongoing tiredness linked to inflammation, poor nutrient absorption or blood loss.
• Unintended weight loss — reduced appetite and chronic inflammation affecting nutritional status.
• Fever — raised body temperature, more common in infectious or severe inflammatory cases.

How is colitis different from irritable bowel syndrome (IBS)?

Colitis and irritable bowel syndrome (IBS) can share similar symptoms, such as abdominal discomfort and changes in bowel habits, but they are fundamentally different conditions in terms of cause, investigation findings and long-term implications.

Who is at risk of colitis in Singapore?

Colitis can affect individuals of all ages, but certain groups have a higher likelihood of developing specific types of the condition. Risk factors vary depending on whether the inflammation is infectious, inflammatory, vascular or medication-related.

• Individuals with a family history of inflammatory bowel disease — a genetic predisposition increases the risk of developing conditions such as ulcerative colitis or Crohn’s disease.
• Young adults and middle-aged individuals — inflammatory bowel disease commonly presents between adolescence and early adulthood, although it can occur at any age.
• Older adults — ischaemic colitis is more frequent in older individuals, particularly those with cardiovascular disease or circulation problems.
• People with weakened immune systems — those undergoing chemotherapy, long-term steroid therapy or living with chronic illness may be more susceptible to infectious colitis.
• Travellers or individuals exposed to contaminated food or water — this increases the risk of infectious colitis.

Can colitis lead to complications?

Yes, colitis can lead to complications, particularly if inflammation is severe, prolonged or not adequately controlled. The risk varies depending on the type of colitis and how early treatment is started.

• Severe dehydration — ongoing diarrhoea can lead to significant fluid and electrolyte loss, especially in acute or infectious cases.
• Anaemia — chronic blood loss from an inflamed colon may reduce haemoglobin levels, causing fatigue and weakness.
• Toxic megacolon — a rare but serious complication where the colon becomes severely dilated and inflamed, requiring urgent medical attention.
• Bowel perforation — severe inflammation can weaken the bowel wall, leading to a tear and potentially life-threatening infection.
• Strictures or narrowing — long-standing inflammation, particularly in Crohn’s disease, may cause scar tissue that narrows the bowel.
• Increased risk of colorectal cancer — patients with long-term inflammatory bowel disease, especially ulcerative colitis, have a higher risk and require regular surveillance colonoscopy.

How is colitis diagnosed?

In Singapore, diagnosing colitis involves identifying both the presence of inflammation and its underlying cause. A detailed medical history and physical examination are the first steps, followed by targeted investigations to confirm the diagnosis and determine the specific type.

• Blood tests — these assess signs of inflammation, infection, anaemia or nutritional deficiencies. Raised inflammatory markers may suggest active disease.
• Stool tests — used to detect bacterial, viral or parasitic infections and to measure inflammatory markers such as faecal calprotectin, which can help distinguish inflammatory conditions from functional disorders.
• Colonoscopy — a key diagnostic procedure that allows direct visualisation of the colon lining. Areas of redness, ulceration or bleeding can be identified, and tissue samples can be taken.
• Biopsy — small samples of colon tissue examined under a microscope help confirm inflammation and differentiate between types of colitis, including microscopic colitis.
• Imaging studies — CT scans or MRI may be recommended in certain cases to assess complications or evaluate areas beyond the reach of endoscopy.

What are the treatment options for colitis in Singapore?

Treatment for colitis depends on the underlying cause, severity of inflammation, and whether the condition is acute or chronic. The main goals are to control inflammation, relieve symptoms, prevent complications and maintain long-term remission where applicable.

• Supportive care — in mild or infectious cases, treatment may focus on adequate hydration, rest and correction of electrolyte imbalance while the bowel heals.
• Antibiotics — prescribed when a specific bacterial infection is identified as the cause of inflammation.
• Anti-inflammatory medications — drugs such as aminosalicylates are commonly used in inflammatory bowel disease to reduce inflammation in the colon lining.
• Corticosteroids — used for short-term control of moderate to severe flare-ups to rapidly suppress inflammation.
• Immunomodulators — these medications adjust immune system activity and are used in patients with ongoing or steroid-dependent disease.
• Biologic therapies — targeted treatments that act on specific components of the immune response, often recommended for moderate to severe inflammatory bowel disease that does not respond to standard therapy.
• Anti-diarrhoeal or symptom-based treatment — in selected cases, medications may be used to manage diarrhoea or abdominal discomfort once serious inflammation has been excluded.
• Surgical intervention — surgery may be necessary in severe cases, complications such as perforation or toxic megacolon or when medical treatment fails to control symptoms.

Management is often individualised, particularly in chronic inflammatory conditions, and regular follow-up is important to monitor response to treatment and adjust therapy as needed.

Summary 

Colitis refers to inflammation of the colon and can arise from a range of causes, including autoimmune conditions such as ulcerative colitis and Crohn’s disease, infections, reduced blood supply, medication effects or radiation exposure. Symptoms commonly include persistent diarrhoea, abdominal pain, urgency, rectal bleeding and fatigue, though severity varies depending on the underlying type. 

Accurate diagnosis through blood tests, stool analysis, colonoscopy and biopsy is essential to distinguish inflammatory causes from functional disorders such as irritable bowel syndrome and to guide appropriate treatment. Management may involve supportive care, anti-inflammatory medication, immune-modulating therapy or in more severe cases, surgical intervention. Early assessment plays a key role in preventing complications and maintaining long-term bowel health. 

If you are experiencing ongoing bowel symptoms or rectal bleeding, schedule a consultation with Dr Aaron Poh at Alpine Surgical Practice for a comprehensive evaluation and personalised treatment plan.

Frequently Asked Questions (FAQs)