Summary

Acute diverticulitis is inflammation and/or infection of colonic diverticula. It is a common complication of diverticular disease, affecting predominantly the sigmoid colon in Western populations. Presentation includes left lower quadrant pain, fever, and altered bowel habit. Diagnosis is confirmed by CT abdomen/pelvis, which also stages complications using the Hinchey classification. Most cases are uncomplicated and managed conservatively with antibiotics (or even observation in mild cases). Complicated disease (abscess, perforation, fistula, obstruction) requires more intensive management including drainage or surgery.

Key Facts

• Definition: Inflammation/infection of colonic diverticula
• Location: Sigmoid colon (95% in Western populations); right-sided more common in Asia
• Prevalence: 25% of patients with diverticulosis will have diverticulitis
• Classic Presentation: LLQ pain, fever, raised inflammatory markers
• Investigation: CT abdomen/pelvis (gold standard)
• Classification: Hinchey staging (complications)

Clinical Pearls

"Left-Sided Appendicitis": Classic teaching describes diverticulitis as "left-sided appendicitis" — LLQ pain, fever, raised WCC. However, right-sided diverticulitis occurs (especially in Asian populations) and can mimic appendicitis.

Antibiotics Not Always Needed: Recent evidence (AVOD, DIABOLO trials) suggests uncomplicated diverticulitis often resolves without antibiotics. Observation with fluids and analgesia is reasonable for mild cases.

Colonoscopy After Recovery: Follow-up colonoscopy is recommended 6-8 weeks after an episode of diverticulitis to exclude underlying malignancy (which can mimic diverticulitis).

Why This Matters Clinically

Diverticulitis is common in emergency and primary care. Recognising uncomplicated from complicated disease guides management — most patients recover with conservative treatment, but complicated cases require urgent intervention to prevent sepsis and death.

Structured Approach

General:

• Vital signs (fever, tachycardia, hypotension = concern)
• Hydration status

Abdominal Examination:

• Inspect: Distension, scars
• Palpate: LLQ tenderness, mass, peritonism
• Percussion: Tympany (ileus), dullness (mass/abscess)
• Auscultation: Bowel sounds (may be reduced if ileus)
• DRE: Tenderness, mass, blood (rule out other pathology)

Key Findings

Natural History

Most patients with acute diverticulitis recover fully with conservative treatment. ~20-30% will have a recurrent episode. After one complicated episode, the risk of complications with further episodes increases.

Outcomes

Prognostic Factors

Good Prognosis:

• Uncomplicated disease
• Younger age
• No immunosuppression

Poorer Prognosis:

• Faecal peritonitis (Hinchey IV)
• Immunocompromised
• Delayed presentation
• Multiple comorbidities

Key Guidelines

1. AGA Clinical Practice Update (2021) — Supports selective antibiotic use; recommends colonoscopy after first episode.

2. WSES Guidelines (World Society of Emergency Surgery) — Comprehensive guidance on complicated diverticulitis.

Landmark Trials

AVOD Trial (2012) — Antibiotics in uncomplicated diverticulitis

• RCT comparing antibiotics vs observation
• Key finding: No difference in outcomes for uncomplicated disease
• Clinical Impact: Antibiotics not always necessary

DIABOLO Trial (2017) — Similar findings

• Observational treatment non-inferior to antibiotics for uncomplicated diverticulitis
• Clinical Impact: Reinforced conservative approach

LADIES Trial / SCANDIV (2015-2019) — Laparoscopic lavage vs resection for Hinchey III

• Mixed results; lavage has higher reoperation rate
• Clinical Impact: Lavage remains controversial; resection often preferred

Evidence Strength

What is Diverticulitis?

Diverticula are small pouches that can form in the wall of your large bowel (colon), particularly in the lower left part. Many people have these pouches (diverticulosis) without any problems. Diverticulitis happens when one or more of these pouches becomes inflamed or infected.

Why does it matter?

Most cases of diverticulitis are mild and get better with rest and sometimes antibiotics. However, it can become serious if the pouch bursts (perforates) or forms an abscess. Recognising the symptoms early and getting treatment prevents complications.

What are the symptoms?

• Pain in the lower left abdomen (usually constant, lasting days)
• Fever
• Change in bowel habit (constipation or diarrhoea)
• Feeling unwell, nauseous
• Bloating

How is it treated?

1. Mild cases: You may be able to recover at home with rest, fluids, a soft diet, and sometimes antibiotics.

2. Moderate cases: You may need hospital admission for IV fluids and antibiotics.

3. Complicated cases (abscess, perforation): May need drainage of an abscess or surgery.

4. Elective surgery: Sometimes recommended if you have repeated attacks or complications.

What to expect

• Most people recover within 1-2 weeks
• A camera test (colonoscopy) is usually recommended 6-8 weeks later to check the bowel
• Eating more fibre after recovery may help prevent future episodes
• Some people have repeated attacks; surgery may be discussed

When to seek help

See a doctor urgently if:

• Pain is severe or spreading
• You have a high fever
• You cannot keep fluids down
• You have blood in your stool
• You feel faint or very unwell