Diverticular disease

Introduction

Diverticular disease encompasses a spectrum of conditions characterised by the presence of diverticula—small mucosal outpouchings that form in the colon wall. The two main clinical entities are:

• Diverticulosis – the presence of diverticula without inflammation (usually asymptomatic).
• Diverticulitis – inflammation and/or infection of one or more diverticula, leading to clinical symptoms.

Peak Incidence

• Prevalence increases with age:
  • Rare under the age of 40.
  • Affects over 50% of people >60 years.

Pathophysiology

• Diverticula form due to increased intraluminal pressure, usually in areas where blood vessels penetrate the muscular wall of the colon.
• Low dietary fibre and chronic constipation are thought to contribute.
• Diverticulitis occurs when a diverticulum becomes obstructed or microperforated, leading to inflammation and sometimes infection.

Symptoms

Diverticulosis:

• Usually asymptomatic.
• May present with vague lower abdominal discomfort, constipation, or altered bowel habits.
• Occasionally associated with painless rectal bleeding (haematochezia).

Diverticulitis:

• Left lower quadrant (LLQ) abdominal pain (right-sided pain is more common in Asian populations).
• Fever and chills.
• Nausea and vomiting.
• Altered bowel habits – diarrhoea or constipation.
• Urinary symptoms (e.g. dysuria) if inflammation is near the bladder.
• Rectal bleeding – less common.

Signs

• LLQ tenderness on palpation.
• Fever, tachycardia.
• Abdominal distension in cases of obstruction.
• Peritonism in perforation (guarding, rebound tenderness).
• Palpable mass if an abscess is present.

Diagnosis

Diverticulosis

• Bloods:
  • FBC, CRP, and U&Es often normal.
• Imaging:
  • Colonoscopy (only if indicated to rule out other causes, e.g. bleeding or altered bowel habit).
  • CT colonography or double-contrast barium enema (historically used but now largely replaced).

Diverticulitis

• Blood tests:
  • FBC: ↑ WCC
  • CRP: Raised
  • U&Es: May show dehydration or AKI
  • Hb: May be low if bleeding present
• Imaging (first-line):
  • CT abdomen/pelvis with IV contrast – confirms diagnosis and assesses complications:
    • Colonic wall thickening (>3 mm)
    • Pericolic fat stranding
    • Abscesses
    • Perforation (free air)
    • Obstruction
• Additional imaging:
  • Erect chest X-ray: may show free air under diaphragm in perforation.
  • AXR: limited utility, may show obstruction.
  • MRI or ultrasound: alternative in pregnancy or when CT is contraindicated.

Complications

• Abscess formation
• Bowel obstruction
• Fistulae (commonly colovesical or colovaginal)
• Perforation leading to peritonitis
• Haemorrhage (from eroded vessels in diverticula)
• Sepsis
• Strictures causing chronic obstruction

Management

Diverticulosis

• Focus on prevention and symptom control:
  • High-fibre diet (25–30 g/day)
  • Bulk-forming laxatives (e.g. ispaghula husk)
  • Physical activity
  • Smoking cessation
  • Weight management
  • Limit alcohol

Diverticulitis

Uncomplicated Diverticulitis:

• Conservative treatment:
  • Bowel rest (clear fluids initially → low-fibre → high-fibre as symptoms resolve)
  • Selective use of antibiotics (may not be needed in mild cases)
    • Indicated for high-risk or immunocompromised patients.
    • First-line: Oral co-amoxiclav for 5 days
  • Analgesia:
    • Paracetamol is preferred
    • Avoid NSAIDs and opioids due to risk of perforation and ileus

Complicated Diverticulitis (e.g. abscess, perforation, fistula):

• Hospital admission

• Nil by mouth

• IV fluids and IV antibiotics (e.g. ceftriaxone + metronidazole)

• CT-guided drainage of abscess if present

• Surgical intervention if:

  • Perforation with peritonitis
  • Fistulae
  • Failed conservative management
  • Obstruction