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Acute Appendicitis

  • The appendix is a blind ended tube connected to the caecum, located in right lower quadrant

Anatomy

  • The appendix is located at the terminal end of the caecum, where the three taeniae join
  • It is about 5-10 cm in size
  • Supplied by the appendiceal artery
    • Abdominal aorta → superior mesenteric a. → ileocolic a. →appendiceal artery
  • Positions of the appendix can be – retrocaecal, pre-ileal, post-ileal, pelvic, subcaecal, paracaecal

Epidemiology/Etiology

  • Most common in males and Caucasians
  • Low fibre diet
  • Family history
  • Viral infection causes mucosal edema and inflammation – eventually gets infected by bacteria and causes appendicitis
  • Most common organisms – E.coli, enterococci, streptococci, bacteroides
  • Pseudoappendicitis – acute ileus following Yersinia infection can mimic acute appendicitis
  • Obstructive appendicitis is due to obstruction of the appendix lumen, can be as a result of
    • Blockage – faecoliths, stricture, foreign bodies, roundworms
    • Adhesions and kinking – carcinoma caecum

Pathogenesis

Acute non-obstructive appendicitis (Features – redness, edema, haemorrhage)

  • Acute inflammation of mucous membrane with secondary infection without obstruction
  • Can lead to resolution, ulceration, fibrosis, recurrent appendicitis, gangrene, peritonitis

Acute obstructive peritonitis (Features – blackish, edema, gangrenous)

  • Mucus and inflammatory fluid collects inside lumen – leads to increased intraluminal pressure, which results in
    • Blockage of lymphatic and venous drainage – causing mucosal ulceration and ischemia
    • Thrombosis of appendicular artery – causing ischemic necrosis of full thickness of wall of appendix
      • This leads to gangrene of appendix and subsequent perforation
      • Perforation leads to bacterial spread through submucosa and muscularis propria
  • After perforation, the suppuration and pus forms an appendicular abscess
    • The abscess is localised by the greater omentum and dilated ileum
  • If the abscess spreads it can cause peritonitis

Recurrent appendicitis

  • Repeated attacks of non-obstructive appendicitis leads to fibrosis and adhesions

Subacute appendicitis – milder form of acute appendicitis

Stump appendicitis – retained long stump of appendix after laparoscopic appendectomy

Clinical features

  • Murphy’s triad – pain, vomiting, temperature
    • Periumbilical pain that moves to right iliac fossa, exacerbation of pain with coughing
    • Vomiting – due to reflex pylorospasm
  • Constipation
  • Fever, tachycardia
  • Urinary frequency – inflamed appendix causes bladder irritation
  • Perforation – intense diffuse abdominal pain, fever, tachycardia

Signs

  • McBurney’s point – tenderness and rebound tenderness
  •  Sherren’s triangle – area of tenderness found characteristically found in acute appendicitis
    • The triangle boundaries are the umbilicus, the anterior superior iliac spine and the pubic symphysis
  • Dunphy’s sign – pain on coughing
  • Rovsing’s sign – pain in right iliac fossa when palpating left iliac fossa
  • Obturator’s sign (pelvic appendicitis) – pain on internal rotation of hip
  • Iliopsoas sign (retrocaecal appendicitis) – pain on extension of right hip
  • Sitkovskiy’s sign – when patient turns onto left hand side there is pain on the right hand side

Differential diagnosis

  • Perforated duodenal ulcer – fluid trickles down right paracolic gutter and mimics appendicitis
    • Upper abdominal pain and gas under diaphragm differentiate the conditions
  • Acute cholecystitis – pain in upper right quadrant, fever, jaundice,
    • US and LFTs to differentiate
  • Acute pancreatitis – epigastric pain radiating to back, raised amylase and lipase
  • Acute bacterial enterocolitis – pain in abdomen, diarrhoea, toxaemia, dehydration
  • Crohn’s disease
  • Meckel’s diverticulitis
  • ISS – more common in <2 year olds whereas appendicitis is rare <2 year olds

Investigations

  • Ultra sound – classifies the appendicitis into
    • Catarrhal – clear layer structure of appendiceal wall and mucosal edema
    • Phlegmonous – ill-defined layer structure of appendiceal wall, moderate enlargement of appendix
    • Gangrenous – unidentifiable layer structure of appendiceal wall and marked enlargement to form a mass
  • Laparoscopy
  • Contrast CT – shows dilated appendix and lumen, thickened wall, non-filling of lumen by contrast, presence of mass/abscess
  • X-ray
  • ↑WCC and CRP

Treatment

  • Surgical approaches for appendectomy
    • Gridiron incision – incision is perpendicular to the right spinoumbilical line at the McBurney’s point
    • Lanz crease incision – cosmetically better
    • Laparoscopic approach
  • IV antibiotics – metronidazole, cefuroxime

Complications

  • Perforation
  • Appendix mass – inflamed appendix becomes covered by omentum
  • Appendix abscess – when appendix mass fails to resolve but enlarges and requires surgical drainage and ABs
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