Acute appendicitis

Acute appendicitis is the most common abdominal surgical emergency in the world, with around 50 000 and 300 000 acute appendicectomies performed annually in the UK and in the US respectively. 1 2However, its incidence is falling for unknown reasons. 3 4 This clinical update provides information on how patients may present and what investigations and treatments are available. Who is affected?Acute appendicitis can affect people of any age but is most common between the ages of 10 and 20 years. 4 5It is more common in males, although females are twice as likely to undergo an appendicectomy. 6 7The lifetime risk of acute appendicitis is 8.6% in males and 6.9% in females; the lifetime appendicectomy rate is 12% in males and 23% in females. 6 7Perforation is found in 13-20% of patients with acute appendicitis. 8 9 What causes appendicitis?The aetiology remains uncertain, 7-10 but possible causes include luminal obstruction blocking the escape of mucosal secretions and leading to an increase in pressure, causing engorgement and stasis that can lead to necrosis and eventually perforation. 7 90][11][12] There is no known genetic cause of acute appendicitis, but increased risk has been observed in twin studies and in those with a positive family history. 13 14 How do patients present with acute appendicitis?0][21] The differential diagnoses are broadest in pre-menopausal women, as symptoms of acute appendicitis can be similar to the pain some women experience during normal menstruation, dysmenorrhoea, or ovulation and pathology such as ovarian torsion, ectopic pregnancy, and pelvic inflammatory disease. 15Diagnosis is harder if communication is limited-for example, where there is a language barrier or in patients who are very young, have dementia, a mental health diagnosis or a learning difficulty. 20In these patients, a collateral history of becoming withdrawn, less active, or having a reduced oral intake will raise the index of suspicion.