Appendicitis is inflammation of the appendix.  It is the most common cause of acute abdomen in the UK, and the most common childhood surgical emergency.


Factors associated with a higher incidence of appendicitis include:

  • Female sex
  • Ages 10-30 years: in infancy the appendix lumen is wide and well drained, and in old age the lumen has almost disappeared. Therefore appendicitis is rare in these age groups.
  • Higher socioeconomic class
  • Low fibre diet




    Acute appendicitis is caused by infection of the appendix wall following obstruction of the lumen. The obstruction may be due to a faecolith (a hard lump of faeces that may form when transit time is prolonged), lymphadenitis, intestinal worms or a stricture from previous inflammation.  The subsequent infection results in an increased intraluminal pressure due to a build up of mucus, which in turn results in occlusion of small vessels and necrosis of the wall.  This weakens the structure of the wall and can ultimately lead to a ruptured appendix. Consequently this may cause generalised peritonitis, which is associated with a higher mortality rate, or a localised appendix abscess, in which the inflamed appendix is covered in omentum and walled off from the rest of the abdominal cavity.

    Chronic, or ‘rumbling’ appendicitis is simple inflammation in the absence of infection, and as such is not a surgical emergency (although it can be very painful for the patient).  However, the appendix is often removed on an elective basis. This is because the chronic inflammation can result in adhesions or strictures within the lumen, leading to an attack of acute appendicitis.


    Clinical picture

    Signs and symptoms of acute appendicitis

    If a patient has a retrocaecal or pelvic appendix the clinical picture may be different.

    Retrocaecal appendix: pain is often not as severe as in classical appendicitis. Pain may not be felt in the RIF even upon deep palpation.  Rectal examination will show tenderness in the rectovesical pouch, and psoas and obturator tests will be positive.

    Pelvic appendix: may cause diarrhoea and increased frequency of micturation due to contact with the rectum and bladder.  Psoas and obturator tests will also be positive.


    Appendicitis in children, the elderly or pregnancy may present differently, with less specific signs and symptoms.  As such, misdiagnosis, perforation and other complications are more common.


    Differential Diagnosis


    Gastrointestinal conditions:

    • Mesenteric adenitis: pain is localised above and medial to McBurney’s point, and occurs following a respiratory tract infection.  Most common in children.
    • Food poisoning: associated diarrhoea.
    • Diverticulitis: most commonly presents with left sided pain, but right sided diverticula are possible.
    • Crohn’s disease: usually patients will have a prolonged history of vague abdominal and systemic symptoms.  Bloody diarrhoea, weight loss/growth failure, involvement of the mouth or anus, or presence of other stigmata of autoimmune disease (e.g. uveitis, skin involvement) would suggest Crohn’s disease.
    • Perforated ulcer: either epigastric pain or sudden non-localised peritonitis without prior pain in the RIF.
    • Meckel’s diverticulum: usually only becomes symptomatic in those under two years of age, but can present with all the features of acute appendicitis.


    Biliary conditions:

    • Cholecystitis: pain usually higher in the right upper quadrant, although there may be tenderness in the RIF.


    Urological conditions:

    • Cystitis: this diagnosis is complicated by involvement of the bladder in retrocaecal appendicitis.
    • Renal colic: pain often comes in waves due to peristalsis of the ureter, and extends from loin to groin.
    • Testicular torsion: may present with periumbilical pain and vomiting.


    Gynaecological conditions:

    • Salpingitis/pelvic inflammatory disease: pain usually more generalised and cervical excitation is present.
    • Ectopic pregnancy: positive pregnancy test!
    • A history of dysmenorrhoea and irregular menstruation would indicate a variety of gynaecological conditions such as torsion or rupture of an ovarian cyst, endometriosis or ovulation pain (Mittelschmerz).


    As mentioned above, a certain subset of patients will present with more vague symptoms, and therefore there will be more differential diagnosis to be considered.




    Appendicitis is usually a clinical diagnosis following a history and examination. A raised neutrophil count supports the diagnosis.  The use of investigations in suspected acute appendicitis is controversial. Abdominal CT reduces the rates of negative appendectomy, but may delay intervention and lead to deterioration in the patient’s condition.

    REMEMBER: a pregnancy test is crucial for abdominal pain in all women of child-bearing age.

    REMEMBER: examination of the testes in all boys with abdominal pain is mandatory to rule out torsion and maldescent.

    The Alvarado scoring system was developed to assist in the difficult diagnosis of appendicitis:

    • Migration of pain:         1pt
    • Nausea/vomiting:         1pt
    • Anorexia:                    1pt
    • RIF tenderness:           2pt
    • Rebound pain:             1pt
    • Temperature >37.3°C   1pt
    • WCC > 10x109/L         2pt
    • Neutrophil count >75% 1pt


    Total score

    • </= 4 - appendicitis unlikely
    • 5-6  - patient should be observed
    • =/> 7  - emergency operation


    A common mnemonic used to remember the scoring system is MANTRELS:

    Migration to the RIF



    Tenderness in the RIF

    Rebound tenderness

    Elevated temperature


    Shift of leukocytes to the left (i.e. neutrophilia)




      Acute appendicitis is treated by emergency appendectomy.  However, if an appendix mass has formed, conservative management is appropriate until it has resolved.  Appendectomy is then performed.  If a mass fails to resolve it may form an appendix abscess, which is seen clinically by a marked deterioration in the patient’s condition.  This will require drainage and surgical intervention.


      Preoperative preparation

      Patient must be kept nil by mouth.  They will require pain relief, and anti-emetic medication.  Hydration status must be assessed and fluids prescribed.

      Preoperative antibiotics are crucial and reduce the risk of peritonitis, appendix abscess and wound infection.  Typically 1-3 doses of metronidazole 500mg and cefuroxime 1.5g every 8hrs is given 1hour before surgery.  A prolonged course of 7-10 days will be required in those with rupture.



      Laparoscopic appendectomy is widely used as it reduces scarring and wound infections. There are a number of other advantages such as reduced postoperative pain, the length of hospital stay, and a low risk of adhesions from surgery itself.  If the appendix is not inflamed, then evaluation of other abdominal structures can be easily performed.  However, if the appendix is necrotic or ruptured then it may be necessary to convert the lapararoscopic procedure to an open appendectomy.  The location of the resulting scar, which you will still see on many patients, is shown below.


      Common abdominal scars

      Postoperative care

      Clear fluids are introduced the day after surgery, and a regular diet soon after.  The patient must be encouraged to mobilise early, and pain must be managed according to the patient’s needs.



      • Paralytic ileus: treat with analgesia, antibiotics and gastric aspiration.  Usually resolves after a few days.
      • Local wound infection.
      • Pelvic abscess: particularly following removal of ruptured gangrenous appendix.





      The majority of patients recover quickly. Following a laparoscopic appendectomy time to full activity is 1-2 weeks, and 2-3 weeks following an open operation.


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