Acute appendicitis

  • Acute abdominal pain is defined as previously undiagnosed pain of <72 hours duration
  • Accounts for about 2% of hospital admissions
  • In only 50% of patients is the preoperative diagnosis correct
  • Right iliac fossa pain accounts for about half of all cases of acute abdominal pain

Causes of right iliac fossa pain

  • Appendicitis
  • Urinary tract infection
  • Non-specific abdominal pain
  • Pelvic inflammatory disease
  • Renal colic
  • Ectopic pregnancy
  • Constipation

Causes of right iliac fossa mass

  • Appendix mass
  • Crohn's disease
  • Caecal carcinoma
  • Mucocele of the gallbladder
  • Psoas abscess
  • Pelvic kidney
  • Ovarian cyst


  • About 10% of the population will develop acute appendicitis
  • The incidence is falling

Risk of appendicitis with age

  • 70,000 appendicectomies are performed each year in the UK
  • Appendicitis is more common in men
  • Appendicectomy is performed more often in women
  • At 10-20% appendicectomies a normal appendix is removed
  • The risk of perforation is:
    • Less than 10 years old = 50%
    • 10-50 years old = 10%
    • Over 50 years old = 30%
  • A women is more likely to have a 'normal' appendix removed

Clinical features of appendicitis

  • Central abdominal pain moving to right iliac fossa
  • Nausea, vomiting, anorexia
  • Low-grade pyrexia
  • Localised tenderness in right iliac fossa
  • Right iliac fossa peritonism
  • Percussion tenderness is a kinder sign of peritonism than rebound
  • Rovsing's sign = pain in right iliac fossa on palpation of the left iliac fossa


  • Appendicitis is essentially a clinical diagnosis
  • The following may be useful:
  • Urinalysis may exclude urinary tract infection
  • Pregnancy test to exclude ectopic pregnancy
  • Abdominal x-ray is of little value
  • A normal white cell count does not exclude appendicitis
  • Ultrasound may be helpful in the assessment of an appendix mass or abscess
  • Ultrasound adds little to the clinical diagnosis of acute appendicitis
  • Scoring systems and computer-aided diagnosis my be helpful
  • Meta-analysis suggest the following to be useful predictors of appendicitis in patients with abdominal pain
    • Raised inflammatory markers
    • Clinical signs of peritoneal irritation
    • Migration of abdominal pain

Ultrasound appearances of acute appendicitis

Picture provided by Fahid Abu-Zant, Neblus Speciality Hospital, Neblus, Palestine


  • In cases of diagnostic doubt a period of 'active observation' is useful
  • Active observation reduces negative appendicectomy rate without increased risk of perforation
  • Intravenous fluids and analgesia should be given
  • Opiate analgesia does not mask the signs of peritonism
  • Antibiotics should not be given until a decision to operate has been made
  • Diagnostic laparoscopy should be considered particularly in young women
  • Whether a 'normal' appendix should be removed following laparoscopy is unclear


  • Early appendicectomy for non-perforated appendicitis was first performed in 1880s
  • Open appendicectomy is usually performed via a Lanz incision and muscle splitting approach
  • No evidence that burying the stump reduces the infection rate
  • Consider a midline incision in elderly patients
  • If normal appendix removed need to look for:
    • Meckel's diverticulum
    • Acute salpingitis
    • Crohn's disease

Acute appendicitis

  • Laparoscopic appendicectomy may be associated with:
    • reduced hospital stay
    • rapid return to normal activity
  • Overall benefits of laparoscopic approach not as great as for cholecystectomy

laparoscopic appendicectomy

Appendix mass

  • Usually presents with a several day history
  • Inflammation localised to the right iliac fossa by the omentum
  • Patient is usually pyrexial with a palpable mass
  • Initial treatment should be conservative
  • Fluids, analgesia and antibiotics
  • Observe the patient and mass
  • Continue conservative whilst there is clinical improvement

Position of the appendix

Appendix abscess

  • Results from localised perforation
  • Abscess should be surgically or percutaneously drained
  • Appendicectomy at initial operation can be difficult
  • Need for appendicectomy after abscess drainage is unclear

Picture provided by Dr Florencia Castro,  Hospital Juan de San Martin, Buenos Aires, Argentina


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Last updated: 09 November 2010

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