Appendicitis

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

Definition

Appendicitis is the inflammation of the appendix, often due to obstruction of the lumen, leading to bacterial infection and potential perforation.

Aetiology

  • Luminal obstruction: commonly caused by a faecolith, lymphoid hyperplasia, or, rarely, a neoplasm.
  • Bacterial infection: overgrowth of gut bacteria such as Escherichia coli and Bacteroides fragilis.
  • Viral infections: can cause lymphoid hyperplasia leading to obstruction.

Pathophysiology

  • Obstruction of the appendix leads to mucus accumulation and increased intraluminal pressure.
  • Ischaemia and bacterial overgrowth cause inflammation and pus formation.
  • If untreated, it can progress to perforation, abscess formation, or peritonitis.

Risk factors

  • Age: most common in children and young adults (10–30 years).
  • Family history of appendicitis.
  • Low-fibre diet (linked to faecolith formation).
  • Previous gastrointestinal infections.

Signs and symptoms

  • Abdominal pain: initially periumbilical, later localising to the right iliac fossa (RIF).
  • Fever: low-grade in early stages, higher if perforation occurs.
  • Nausea and vomiting.
  • Loss of appetite (anorexia).
  • Localised tenderness: mcBurney’s point (1/3 of the way from the anterior superior iliac spine to the umbilicus).
  • Rebound tenderness: suggests peritoneal irritation.
  • Rovsing’s sign: pain in RIF when pressing on the left iliac fossa.
  • Psoas sign: pain on hip extension (suggests retrocaecal appendix).

Investigations

  • Blood tests:
    • Raised white cell count (infection).
    • Elevated CRP (inflammation).
    • Serum electrolytes (assess hydration).
  • Urinalysis: to exclude urinary tract infection.
  • Imaging:
    • Ultrasound: preferred first-line in children and pregnant women.
    • CT abdomen (gold standard): confirms diagnosis and assesses for perforation.

Management

1. Initial Resuscitation:

  • IV fluids: to maintain hydration.
  • Analgesia: paracetamol or opioids if severe.
  • IV antibiotics: broad-spectrum (e.g., co-amoxiclav or cefuroxime + metronidazole).

2. Definitive Treatment:

  • Laparoscopic appendicectomy (first-line): preferred surgical approach.
  • Open appendicectomy: if complicated perforation or abscess.

3. Conservative Management:

  • Antibiotic-only approach: considered in selected cases of uncomplicated appendicitis.
  • Drainage of abscess: if appendiceal abscess is present, percutaneous drainage may be needed.
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