Appendicitis

Question 1

Appendicitis Epidemiology

Answer 1

• 6% of population, M>F

* 80% between 5-35 yrs of age

Question 2

Appendicitis Pathogenesis

Answer 2

luminal obstruction

• > bacterial overgrowth
• > inflammation/swelling
• > increased pressure
• > localized ischemia
• > gangrene/perforation
• > localized abscess (walled off by omentum) or peritonitis
• etiology:
  
  • children or young adult:
    
    • hyperplasia of lymphoid follicles, initiated by infection
  • adult:
    
    • fibrosis/stricture, fecolith, obstructing neoplasm
  • other causes:
    
    • parasites, foreign body

Question 3

Appendicitis Clinical Features

Answer 3

• most reliable feature is progression of signs and symptoms
• low grade fever (38°C), rises if perforation
• abdominal pain then anorexia, nausea and vomiting
• classic pattern: pain initially periumbilical; constant, dull, poorly localized, then well localised pain over McBurney’s point
  * due to progression of disease from visceral irritation (causing referred pain from structures of the embryonic midgut, including the appendix) to irritation of parietal structures
  * McBurney’s sign
• signs:
  * inferior appendix:
  * McBurney’s sign (see above), Rovsing’s sign (palpation pressure to left abdomen causes McBurney’s point tenderness)
  * retrocecal appendix:
  * psoas sign (pain on flexion of hip against resistance or passive hyperextension of hip)
  * pelvic appendix:
  * obturator sign (flexion then external or internal rotation about right hip causes pain)
  
  • complications:
    
    • perforation (especially if>24 h duration)
    • abscess, phlegmon

Question 4

Appendicitis Investigations

Answer 4

• labs:
  * mild leukocytosis with left shift (may have normal WBC counts)
  * higher leukocyte count with perforation
  * Beta-hCG to rule out ectopic pregnancy
  * urinalysis
• imaging:
  * upright CXR, AXR:
  * usually nonspecific - free air if perforated (rarely), calcified fecalith, loss of psoas shadow, RLQ ileum,
  * ultrasound:
  * may visualize appendix, but also helps rule out gynecological causes - overall accuracy 90-94%, can rule in but CANNOT rule out appendicitis (if >6 mm, SENS/SPEC/NPV/PPV 98%)
  * CT scan:
  * thick wall, appendicolith, inflammatory changes- overall accuracy 94-100%, optimal investigation

Question 5

Appendicitis Treatment

Answer 5

• hydrate, correct electrolyte abnormalities
• surgery (gold standard, 20% mortality with perforation especially in elderly) + antibiotic coverage
• if localized abscess (palpable mass or large phlegmon on imaging and often pain >4-5 d), consider radiologic drainage + antibiotics x 14 d ± interval appendectomy in 6 wks (controversial)
• appendectomy:
  * laparoscopic vs. open
  * complications: spillage of bowel contents, pelvic abscess, enterocutaneous fistula
  * perioperative antibiotics:
  * ampicillin +gentamicin+ metronidazole (antibiotics x 24 h only if non-perforated)
  * other choices: 2nd/3rd generation cephalosporin for aerobic gut organisms
  • colonoscopy in the elderly

Question 6

Appendicitis Prognosis

Answer 6

• morbidity/mortality 0.6% if uncomplicated, 5% if perforated