Diverticular Disease

Definition | Aetiology | Pathophysiology | Risk Factors | Signs and Symptoms | Investigations | Management | Referral

Definition

Diverticular disease refers to the presence of diverticula (small mucosal outpouchings) in the colon, which may be asymptomatic or cause symptoms. When inflammation occurs, it is termed diverticulitis.

Aetiology

  • Increased intraluminal pressure: causes herniation of the colonic mucosa through weak points in the bowel wall.
  • Low-fibre diet: leads to harder stools and increased pressure on the colonic wall.
  • Aging-related changes: weakening of the colonic wall with age.

Pathophysiology

  • High colonic pressures result in the formation of diverticula, usually in the sigmoid colon.
  • Faecal stasis within diverticula may cause bacterial overgrowth and inflammation, leading to diverticulitis.
  • Complications such as abscesses, perforation, or fistula formation can occur.

Risk factors

  • Age >50 years.
  • Low-fibre diet.
  • Chronic constipation.
  • Obesity.
  • Smoking.
  • NSAID or corticosteroid use (increased risk of perforation).

Signs and symptoms

Diverticulosis (asymptomatic):

  • Usually detected incidentally on colonoscopy or imaging.

Diverticular disease (symptomatic but without inflammation):

  • Intermittent lower abdominal pain (often left-sided).
  • Bloating and altered bowel habits (diarrhoea or constipation).

Diverticulitis (inflamed diverticula):

  • Acute onset of persistent left lower quadrant pain.
  • Fever and systemic signs of infection.
  • Nausea and vomiting.
  • Change in bowel habits.
  • Rectal bleeding (if complications like fistula or perforation occur).

Investigations

  • Clinical Examination:
    • Perform an abdominal examination to assess for tenderness on palpation, mass, and LLQ guarding.
    • In women, perform a pelvic examination to check for gynaecological causes.
    • Digital rectal examination (DRE) to assess for rectal masses, tenderness, or occult blood.
  • Blood tests:
    • Raised white cell count and CRP (suggests infection).
    • Check renal function before contrast imaging.
  • CT abdomen with contrast (gold standard): identifies inflammation, abscesses, or perforation.
  • Colonoscopy: contraindicated in acute diverticulitis due to risk of perforation but used for long-term evaluation.
  • Abdominal X-ray: may show signs of obstruction or free air if perforation is present.
  • Faecal Immunochemical Test (FIT): used to rule out other causes such as colorectal malignancy.
  • Urinalysis: helps exclude urinary tract infections or other renal causes of pain.

Management

1. Diverticulosis (Asymptomatic):

  • High-fibre diet and adequate hydration to prevent complications.
  • Routine follow-up with primary care.

2. Uncomplicated Diverticular Disease:

  • Increase dietary fibre intake.
  • Simple analgesia (paracetamol; avoid NSAIDs to reduce perforation risk).
  • Antispasmodics (e.g., mebeverine) for symptom relief.

3. Acute Diverticulitis:

  • Oral antibiotics: if mild and managed in the community:
    • Prescribe co-amoxiclav 500/125 mg three times daily for 5 days.
    • If penicillin allergy or co-amoxiclav is unsuitable:
      • Cefalexin (500 mg twice or three times daily for 5 days [up to 1 to 1.5 g three or four times daily for severe infection]) plus metronidazole (400 mg three times daily for 5 days), or
      • Trimethoprim (200 mg twice daily for 5 days) plus metronidazole (400 mg three times daily for 5 days).
  • IV antibiotics: if admitted with moderate-to-severe symptoms.
  • Nil by mouth and IV fluids: if admitted for bowel rest.
  • Pain management: paracetamol and opioids if necessary.

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

  • CT-guided drainage: for abscesses.
  • Emergency surgery: if perforation or obstruction occurs (e.g., Hartmann’s procedure).

Referral

  • Routine gastroenterology referral: if ongoing symptoms or need for long-term colonoscopic surveillance.
  • Urgent surgical referral: if peritonitis, perforation, or obstruction is suspected.
GastroenterologymypanotesDiverticular Disease