Acute appendicitis


  • The diagnosis of appendicitis is basically clinical.
  • The inflammation normally develops over 1–2 days.
  • If the inflammation has developed rapidly the CRP might not have had time to become elevated.
  • Computed tomography (CT) is used to confirm diagnosis in unclear cases.
  • The removal of an inflamed appendix remains the cornerstone of treatment.


  • Appendicitis is most common between the ages of 10 and 30 years, but it is encountered in all age groups. The incidence of acute appendicitis is declining.
  • The aetiology is usually a narrowing/obstruction of the appendiceal lumen.
  • Correct diagnosis is of particular importance in children and the elderly.
  • Appendicectomy is one of the most common surgical emergencies carried out.

Signs and symptoms

  • The classic history consists of upper abdominal pain followed by right lower quadrant (RLQ) pain at the McBurney’s point (picture (McBurney's point and the position of the appendix)).
  • The patient is febrile, often nauseous, vomiting and clearly looks unwell.
  • The physical examination will reveal RLQ tenderness to palpation.
    • Rebound tenderness and pain on percussion
    • If the peritoneum becomes irritated the abdominal wall muscles feel tense (guarding) on palpation.
  • If the appendix ruptures (bursts) the course of the disease will be complicated either by a periappendicular abscess contained by the surrounding tissues or by peritonitis.
  • Only localised inflammation is present in the peritoneum in the early stages, but if the body is unable to contain the inflammation generalised peritonitis will develop.
    • Generalised peritonitis is characterised by more prominent guarding, diminished bowel sounds and worsening general condition.
  • The location of the appendix may vary (picture (McBurney's point and the position of the appendix)).
    • In children, containing the infection is less successful than on average and hence peritonitis develops more easily.
    • In pregnant women, as pregnancy advances, the growing uterus pushes the caecum, and hence also the appendix, upwards, and consequently the pain of appendiceal inflammation moves upwards and laterally.
    • In elderly persons, the clinical picture may be insidious due to weak immune response.
    • A patient with retrocaecal appendicitis presents with pain that is higher and more towards the back than in classic appendicitis. The pain is due to the irritation of the psoas muscle, which lies behind the caecum.
    • Inflammation of an appendix that lies more within the pelvis produces somatic pain lower than the McBurney’s point in the upper pelvic region. The pain can be elicited by contracting the obturator muscle (flexion and internal rotation of the right hip).


  • The diagnosis of typical appendicitis is made on the basis of clinical presentation and the elevation of inflammatory parameters (CRP and white blood cell count). High CRP concentration suggests a complicated disease.
    • The concentrations of the inflammatory parameters have not always had time to increase if appendicitis developed rapidly.
    • Persistent gastroenteritis may lead to the swelling of the appendix, and in such cases the development of appendicitis may be delayed, i.e. a few days after the diarrhoeal disease.
    • When the diagnosis is uncertain, appendicitis can be relatively reliably diagnosed with abdominal CT.
      • A swollen appendix, fluid collection signifying a rupture of the appendix or an already developed abscess may be detected.
  • The probability of acute appendicitis can be estimated by a scoring system 3 . If the probability is low, discharge from hospital without further investigations is safe.
  • Differential diagnosis: see table T1.
Table 1. Differential diagnosis of appendicitis
Differential diagnosis Clinical signs
Gastroenteritis (mesenteric lymphadenitis) Symptoms of intestinal infection, ”innocent” appendix
Urinary tract infection Pyuria and bacteriuria
Right-sided urinary tract stone Microscopic haematuria and colicky pain
Gynaecological infections Abnormal discharge and pain during gynaecological examination
Ectopic pregnancy Positive pregnancy test, often decreased haemoglobin and a positive Kehr’s sign
Ovarian causes Rupture of an ovarian cyst usually causes mild symptoms, torsion produces more severe pain
Diverticulitis with perforation If the sigmoid colon is long, pain in mid/right lower abdomen
Cholecystitis A low-lying gallbladder in an elderly patient


  • Acute appendicitis is primarily treated surgically.
    • If CT scan reveals an appendiceal fecalith or fluid accumulation around the appendix, surgical treatment is usually warranted.
  • Laparoscopic appendicectomy is gaining in popularity [Evidence Level: A]; it is of particular benefit for young female patients.
    • Differential diagnosis in women is made easier with the aid of laparoscopy.
  • Surgery is performed under prophylactic antibiotic cover, usually metronidazole 1 g intravenously .
  • An uncomplicated, CT-confirmed appendicitis may in a hospital setting be treated by antimicrobial medication with a sufficiently broad spectrum (e.g. piperacillin–tazobactam 4 g 3 times daily).
  • If the symptoms of appendicitis are only mild, antibiotics alone may suffice as treatment.
  • The key points in the treatment of peritonitis are the exploration and lavage of the peritoneum, antimicrobial therapy to target pathogens isolated through bacteriological sampling and general supportive measures.
  • Treatment is mostly conservative if a periappendicular abscess has already developed. Operative (laparoscopic) treatment is possible as judged by the surgeon.
    • In these cases, a broad-spectrum antimicrobial agent active against Gram-negative aerobic and anaerobic bacteria is chosen.
    • If indicated, the abscess may be drained with ultrasound/CT guidance.
    • Appendicectomy after successful conservative treatment (interval appendicectomy) is carried out only after consideration. Healing of the appendix should be confirmed with ultrasonography, for example.


1. Ilves I, Paajanen HE, Herzig KH et al. Changing incidence of acute appendicitis and nonspecific abdominal pain between 1987 and 2007 in Finland. World J Surg 2011;35(4):731-8.  [PMID:21327601]
2. Salminen P, Paajanen H, Rautio T et al. Antibiotic Therapy vs Appendectomy for Treatment of Uncomplicated Acute Appendicitis: The APPAC Randomized Clinical Trial. JAMA 2015;313(23):2340-8.  [PMID:26080338]
3. Sammalkorpi HE, Mentula P, Leppäniemi A. A new adult appendicitis score improves diagnostic accuracy of acute appendicitis--a prospective study. BMC Gastroenterol 2014;14():114.  [PMID:24970111]
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