VHOSPITAL.CLINIC · Differential Diagnosis
Diverticulitis vs Irritable Bowel Syndrome (IBS)
Clinical comparison — shared symptoms, key differences, distinguishing diagnostic tests, treatment pathways, and when to seek urgent evaluation.
Condition Overview
Condition A
Diverticulitis
Diverticulitis occurs when diverticula (small pouches in the colon wall) become inflamed or infected, causing left lower quadrant pain, fever, and bowel changes. Uncomplicated cases are treated with antibiotics; perforation or abscess may require surgery.
Condition B
Irritable Bowel Syndrome (IBS)
IBS is a functional gastrointestinal disorder causing recurrent abdominal pain related to defecation, with altered stool frequency or consistency. It affects up to 15% of the population; dietary changes, stress management, and symptom-specific medications help.
Shared Symptoms — Why They're Confused
Both conditions present with 4 overlapping symptoms, making clinical differentiation essential.
Key Clinical Differences
Diverticulitis
- Left lower quadrant abdominal pain
- Change in bowel habit
- Bloating and discomfort
- Symptoms may worsen after eating
Irritable Bowel Syndrome (IBS)
- Functional disorder without structural pathology
- Pain relieved by defecation
- Alternating diarrhoea and constipation
- No fever, normal inflammatory markers
Distinguishing Diagnostic Tests
| Test | Diverticulitis | Irritable Bowel Syndrome (IBS) |
|---|---|---|
| CT abdomen/pelvis | Diverticulae with pericolic fat stranding, abscess, or perforation | Normal — no structural pathology |
| CRP + WBC | Elevated — acute bacterial inflammation | Normal — no inflammation |
| Faecal calprotectin | Mildly elevated during acute episode | Normal — no mucosal inflammation |
Treatment Approaches
Diverticulitis
- •Mild: oral antibiotics (co-amoxiclav or metronidazole + ciprofloxacin)
- •Severe: IV antibiotics, nil by mouth
- •Surgery for perforation or recurrent disease
Irritable Bowel Syndrome (IBS)
- •Dietary modification (high fibre, low-FODMAP)
- •Antispasmodics
- •Probiotics
- •Psychological support
When Doctors Consider Each Diagnosis
🔵 Consider Diverticulitis when:
- →Acute LLQ pain with fever, elevated CRP, diverticulae on CT
🟢 Consider Irritable Bowel Syndrome (IBS) when:
- →Chronic LLQ pain relieved by defecation, normal CT and blood tests, stress-related pattern
Explore Each Condition in Detail
Related Clinical Pages
Diverticulitis
Irritable Bowel Syndrome (IBS)
Medical References
Content on this page is informed by evidence-based clinical sources including:
- World Health Organization (WHO)Global health guidance and disease classification
- National Health Service (NHS)UK clinical guidelines and patient information
- National Institute for Health and Care Excellence (NICE)Evidence-based clinical practice guidelines
- Centers for Disease Control and Prevention (CDC)US public health data and clinical recommendations
- PubMed – NCBIPeer-reviewed biomedical literature and clinical studies
- Cochrane LibrarySystematic reviews and meta-analyses in evidence-based medicine
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