Acute Appendicitis

Acute inflammation of the appendix

Aetiology

  • Results from obstruction of the appendiceal lumen
  • Most commonly affects those in their second or third decade; it is one of the most common causes of abdominal pain in young people and children

Pathophysiology

  • Typically caused by direct luminal obstruction, usually secondary to a faecolith, lymphoid hyperplasia, impacted stool or, rarely, an appendiceal or caecal tumour
  • When obstructed, commensal bacteria in the appendix can multiply, resulting in acute inflammation
  • Reduced venous drainage and localised inflammation can result in increased pressure within the appendix, in turn can result in ischaemia
  • If left untreated, ischaemia within the appendiceal wall can result in necrosis, which in turn can cause the appendix to perforate

Anatomy of pain localisation

  • Main symptom is abdominal pain - central pain that migrates to the right iliac fossa
  • Initial pain from the appendix and its visceral peritoneum is referred to the umbilical region
  • As the appendix becomes increasingly inflamed it irritates the parietal peritoneum, causing pain to localize to the right lower quadrant
  • McBurney's point refers to the point on the lower right quadrant of the abdomen at which tenderness is maximal in cases of acute appendicitis - it corresponds to the location of the base of the appendix when it lies in the retrocaecal position

Clinical presentation

Symptoms

  • Central pain that migrates to the right iliac fossa
  • Anorexia
  • Nausea and vomiting

Signs

  • Mild fever
  • Mild tachycardia
  • Localised pain in RIF
  • Rebound tenderness and percussion pain over McBurney’s point - 1/3 of the distance from the right anterior superior iliac spine to the umbilicus
  • Guarding
  • Specific signs that may be found on examination include:
    • Rosving’s sign - RIF fossa pain on palpation of the LIF
    • Psoas sign - RIF pain with extension of the right hip
    • Obturator sign - pain felt on passive internal rotation of the flexed hip
notion image

Special cases

  • Pelvic appendix - diarrhoea, frequency of micturition
  • Post ileal appendix - rare, diarrhoea, vomiting

Investigations

  • If classical presentation diagnosis is clinical
  • In atypical and non-urgent presentations - USS

Management

  • Appendicectomy
  • IV antibiotics for those who are unable to undergo surgery