Diverticular disease and Acute Diverticulitis ✅

Related Subjects:Acute Cholecystitis |Acute Appendicitis |Chronic Peritonitis |Abdominal Aortic Aneurysm |Ectopic Pregnancy |Acute Cholangitis |Acute Abdominal Pain |Penetrating Abdominal Trauma |Acute Pancreatitis |Diverticular disease and Acute Diverticulitis

📖 About

• 👵 Commonest in the elderly (steep rise after age 60)
• Approx 10–15% of people with diverticulosis develop symptoms).
• ⚠️ Higher risk if immunosuppressed patients, steroids, significant comorbidities.
• 📈 Lifetime risk of developing acute diverticulitis in those with diverticulosis ≈ 4–25% (Western populations).

🧬 Aetiology & Pathophysiology

• Predominantly affects the sigmoid colon (narrowest lumen, highest intraluminal pressures).
• Diverticula = herniation of mucosa/submucosa through points of weakness (vasa recta penetration sites).
• High intraluminal pressure + low-fibre diet → outpouchings → diverticula formation.
• Contributing factors: Western low-fibre/high-fat diet 🍔, altered gut microbiome, colonic motility abnormalities, ageing-related connective tissue weakness.

⚠️ Risk Factors

• Ageing → reduced colonic wall strength.
• Obesity, sedentary lifestyle, smoking 🚬.
• Low-fibre, high-fat/red meat diet.
• Genetic predisposition (familial clustering).
• Immunosuppression or NSAID/steroid use (increases complication risk).

📂 Types (NICE NG147 Terminology)

• Diverticulosis → diverticula present, asymptomatic.
• Diverticular disease → diverticulosis + mild symptoms (e.g. intermittent pain, bowel changes) without inflammation.
• Acute diverticulitis → inflammation/infection of diverticula (uncomplicated or complicated).

🩺 Clinical Features

• Most diverticulosis is asymptomatic (“silent”).
• Diverticular disease: intermittent LLQ pain, bloating, constipation/diarrhoea.
• Acute diverticulitis: constant severe LLQ pain 🔥, fever, nausea/vomiting 🤢, localised tenderness/peritonism, bowel changes.
• Right-sided more common in Asian populations.
• Rectal bleeding (usually painless, bright red) can occur with diverticular bleeding 💉 (separate from diverticulitis).

🚨 Complications (Complicated Acute Diverticulitis)

• Pericolic or distant abscess.
• Fistulae (e.g. colovesical → pneumaturia/faecuria; colovaginal).
• Perforation → purulent/faecal peritonitis (life-threatening).
• Stricture → large bowel obstruction.
• Mass/inflammation mimicking colorectal cancer 🎭 → need to exclude malignancy post-resolution.

🔎 Investigations

• Bloods: ↑WCC, ↑CRP (helps assess severity; CRP >140 mg/L may indicate higher risk).
• Imaging:
  • CT abdomen/pelvis = gold standard for suspected acute diverticulitis (confirms diagnosis, stages complications, Hinchey classification).
  • AXR/CXR if perforation suspected (free air under diaphragm).
  • USS → alternative for abscess detection in some cases.
• Endoscopy: Avoid in acute phase (perforation risk). → Colonoscopy or CT colonography 6–8 weeks after resolution (or sooner if cancer suspected) to exclude malignancy if not recently performed.

📊 Hinchey Classification (Commonly Used CT Staging – Compatible with NG147)

🛠️ Management (NICE NG147 Compliant)

• Diverticulosis & Diverticular Disease (non-inflammatory):
  • No antibiotics.
  • Advise: high-fibre diet (gradual increase), adequate fluids 💧, regular exercise, weight loss if obese, stop smoking.
  • Symptom control: paracetamol for pain, bulk-forming laxatives (e.g. ispaghula) for constipation/diarrhoea. Avoid NSAIDs/opioids if possible.
• Acute Uncomplicated Diverticulitis (systemically well, no significant comorbidities/immunosuppression):
  • Consider no antibiotics (selective use only; no benefit shown in mild cases).
  • Outpatient management if stable: simple analgesia (paracetamol), fluids, rest, clear liquids advancing to low-residue then high-fibre as tolerated.
  • Advise re-presentation if worsening (fever, severe pain, inability to tolerate oral intake).
• Acute Diverticulitis Requiring Antibiotics (systemically unwell, immunosuppressed, significant comorbidities):
  • Oral first-line: Co-amoxiclav 500/125 mg TDS for 5 days.
  • Alternatives (penicillin allergy): Cefalexin + metronidazole, or trimethoprim + metronidazole (per NG147 Table).
  • IV antibiotics if hospitalised (e.g. co-amoxiclav IV or combinations per NG147).
• Complicated Acute Diverticulitis:
  • Hospital admission, IV fluids, IV antibiotics, bowel rest/NBM initially.
  • Abscess <3 cm: often conservative + antibiotics; >3 cm: percutaneous drainage.
  • Perforation/peritonitis: emergency surgery (e.g. Hartmann’s procedure in unstable patients).
  • Fistula/stricture: elective resection after resolution.
• Surgery:
  • Emergency: for generalised peritonitis, uncontrolled sepsis 💀.
  • Elective: individualised after recurrent episodes or complications (laparoscopic preferred if feasible; discuss risks/benefits).
• Recurrent Acute Diverticulitis: No routine antibiotics, aminosalicylates, or probiotics to prevent recurrence (no evidence of benefit).

📚 References (Current as of March 2026)

• NICE NG147 – Diverticular disease: diagnosis and management (2019, current)
• NICE Visual Summary: Antimicrobial prescribing in diverticular disease
• ACPGBI/BSG guidelines (complementary for surgical aspects).

Cases - Diverticular Disease (Updated Examples)

• Case 1 - Asymptomatic Diverticulosis: 60-year-old with incidental diverticula on colonoscopy. Management: High-fibre diet, lifestyle advice, reassurance; no antibiotics or further routine intervention.
• Case 2 - Symptomatic Diverticular Disease: Intermittent LLQ pain, no inflammation. Management: Dietary modification, bulk laxatives, paracetamol; no antibiotics.
• Case 3 - Acute Uncomplicated Diverticulitis: 55-year-old, LLQ pain, mild fever, stable. CT: uncomplicated. Systemically well. Management: Outpatient, no antibiotics, paracetamol, fluids/diet advice; review if no improvement in 48–72 hours.
• Case 4 - Complicated Diverticulitis: 70-year-old, fever, peritonism, CT: 5 cm abscess. Management: Admit, IV antibiotics, percutaneous drainage if >3 cm, surgery if fails.

Teaching Commentary 🥼

Diverticular disease spectrum (NG147): asymptomatic diverticulosis → symptomatic diverticular disease → acute diverticulitis (uncomplicated vs complicated). Key shift: selective antibiotics for acute uncomplicated cases in well patients (no routine use). CT for diagnosis/staging. Focus on lifestyle (high-fibre, fluids, exercise, no smoking). Provide clear information: when to seek help (worsening pain, fever, vomiting, inability to eat). Post-episode colonoscopy if needed to exclude cancer. Surgery individualised for recurrent/complicated disease.