Summary

Acute colitis is sudden inflammation of the colon (large intestine), which can be caused by infections (bacteria, viruses, parasites), inflammatory bowel disease (IBD) flare-ups, ischemia (reduced blood flow), medications, or other causes. Think of your colon as a long tube that processes waste—when it becomes inflamed, it can't function properly, leading to diarrhea (often bloody), abdominal pain, and sometimes fever. This condition is common, with infectious causes being the most frequent, especially in certain settings (hospitals, travel, food poisoning). The severity ranges from mild (self-limiting diarrhea) to severe (toxic megacolon, perforation, sepsis). The key to management is identifying the cause (infection, IBD, ischemia), providing supportive care (fluids, electrolytes), treating infections if present (antibiotics for bacterial causes), managing IBD flares if applicable, and monitoring for complications. Most infectious cases resolve completely, but IBD-related colitis may require ongoing management.

Key Facts

• Definition: Acute inflammation of the colonic mucosa
• Incidence: Common (millions of cases/year), especially infectious
• Mortality: Low (<1%) unless complications (toxic megacolon, perforation)
• Peak age: All ages, but varies by cause
• Critical feature: Diarrhea (often bloody), abdominal pain
• Key investigation: Stool culture, endoscopy, imaging
• First-line treatment: Supportive care, identify and treat cause

Clinical Pearls

"Infectious colitis is most common" — Bacterial infections (C. difficile, E. coli, Salmonella, Campylobacter) are the most common cause of acute colitis. Always consider infection first, especially if recent antibiotics or travel.

"C. difficile is a major cause" — Clostridium difficile colitis is common, especially after antibiotics. It can be severe and needs specific treatment (vancomycin or fidaxomicin).

"IBD can present acutely" — Inflammatory bowel disease (Crohn's, ulcerative colitis) can flare acutely, causing colitis. History of IBD or risk factors should raise suspicion.

"Ischemic colitis is important in elderly" — Reduced blood flow to the colon (ischemia) can cause colitis, especially in older patients with vascular disease. This can be serious and needs prompt recognition.

Why This Matters Clinically

Acute colitis is common and usually mild, but can cause significant symptoms and sometimes serious complications (toxic megacolon, perforation, sepsis). Early recognition and treatment (supportive care, identifying and treating the cause) can prevent complications and provide rapid relief. Most infectious cases resolve completely, but IBD-related colitis may require ongoing management. This is a condition that primary care and emergency clinicians see frequently and can manage effectively with appropriate investigation and treatment.

Structured Approach: ABCDE

A - Airway

• Assessment: Usually patent
• Action: Secure if compromised

B - Breathing

• Look: Usually normal
• Listen: Usually normal
• Measure: SpO2 (usually normal)
• Action: Support if needed

C - Circulation

• Look: May be dehydrated (pale, dry)
• Feel: Pulse (may be high), BP (may be low)
• Listen: Heart sounds (usually normal)
• Measure: BP (may be low), HR (may be high)
• Action: IV fluids if dehydrated

D - Disability

• Assessment: Usually normal (may be unwell if severe)
• Action: Assess if severe

E - Exposure

• Look: Abdominal examination
• Feel: Tenderness, distension
• Action: Complete examination

Specific Examination Findings

Abdominal Examination:

• Inspection: May be distended (if toxic megacolon)
• Palpation:
  • Tenderness: Common (colonic)
  • Guarding/rigidity: If perforation
  • Distension: If toxic megacolon
• Percussion: Usually normal (may be tympanitic if distended)
• Auscultation: Hyperactive bowel sounds (common)

Signs of Dehydration:

• Dry mouth: Dehydration
• Reduced skin turgor: Dehydration
• Tachycardia: Dehydration, sepsis
• Hypotension: Dehydration, sepsis

Special Tests

Natural History (Without Treatment)

Untreated Acute Colitis:

• Infectious: Most resolve spontaneously (weeks)
• C. difficile: May persist or worsen without treatment
• IBD: May become chronic
• Ischemic: May progress to complications

Outcomes with Treatment

Factors Affecting Outcomes:

Good Prognosis:

• Early treatment: Better outcomes
• Mild cases: Usually resolve completely
• Cause identified and treated: Complete recovery
• No complications: Good outcomes

Poor Prognosis:

• Toxic megacolon: Serious, needs urgent treatment
• Perforation: Serious, needs surgery
• Severe cases: May have complications
• Chronic IBD: Ongoing management needed

Prognostic Factors

Key Guidelines

1. NICE Guidelines (2019) — Inflammatory bowel disease. National Institute for Health and Care Excellence

Key Recommendations:

• Steroids for IBD flares
• 5-ASA for maintenance
• Evidence Level: 1A

2. IDSA Guidelines (2017) — C. difficile infection. Infectious Diseases Society of America

Key Recommendations:

• Vancomycin or fidaxomicin first-line
• Metronidazole only for mild cases
• Evidence Level: 1A

Landmark Trials

Multiple studies on C. difficile treatment, IBD management.

Evidence Strength

What is Acute Colitis?

Acute colitis is sudden inflammation of your colon (large intestine). The most common causes are infections (bacteria, viruses), inflammatory bowel disease (IBD) flare-ups, or reduced blood flow (ischemia). Think of your colon as a long tube that processes waste—when it becomes inflamed, it can't function properly, causing diarrhea (often bloody), abdominal pain, and sometimes fever.

In simple terms: Your colon becomes inflamed, causing diarrhea and abdominal pain. Most cases are mild and get better quickly with treatment, but some can be more serious.

Why does it matter?

Most cases of acute colitis are mild and resolve completely with treatment. However, some can cause serious complications (like toxic megacolon or perforation) if not treated. The good news? With proper treatment (supportive care and treating the cause), most people recover completely within days to weeks.

Think of it like this: It's like your colon getting irritated and inflamed—with the right care, it usually heals quickly.

How is it treated?

1. Supportive Care (Most Important):

• Fluids: You may need IV fluids if dehydrated, or oral rehydration if mild
• Rest: Rest helps your body heal
• Diet: You may need to avoid certain foods initially

2. Treating the Cause:

• If it's infection: You may need antibiotics (depending on the type)
• If it's C. difficile: You'll need specific medicines (vancomycin or fidaxomicin)
• If it's IBD: You'll need steroids and other medicines
• If it's other causes: Treat as appropriate

3. Monitoring:

• Watch for complications: Your doctor will monitor you
• Follow-up: You may need follow-up to ensure recovery

The goal: Support your body while it heals, treat the cause, and prevent complications.

What to expect

Recovery:

• Most cases: Start feeling better within days
• Diarrhea: Usually improves within days to weeks
• Full recovery: Most people are back to normal within 1-2 weeks

After Treatment:

• Lifestyle: You may need to avoid certain foods initially
• Medications: You may need to take medicines for a few days to weeks
• Follow-up: Usually not needed unless symptoms persist

Recovery Time:

• Mild cases: Usually recover within days to weeks
• Moderate cases: Usually recover within weeks
• Severe cases: May take longer, may need hospital care

When to seek help

See your doctor if:

• You have persistent diarrhea or abdominal pain
• You have bloody diarrhea
• You have fever
• You have symptoms that concern you

Call 999 (or your emergency number) immediately if:

• You have severe abdominal pain
• You have signs of severe dehydration (dizziness, very dry mouth)
• You feel very unwell
• You have a very distended abdomen

Remember: If you have persistent diarrhea, especially if it's bloody or you have severe pain, see your doctor. Most cases are easily treated, but some can be more serious and need prompt attention.