What causes acute appendicitis?

From the Guidelines

Appendicitis is primarily caused by a blockage of the appendix lumen, typically by a fecalith, lymphoid hyperplasia, or occasionally by foreign bodies, tumors, or parasites, as confirmed by the 2017 WSES guidelines for management of intra-abdominal infections 1.

Causes of Appendicitis

The blockage of the appendix lumen leads to bacterial multiplication, infection, and inflammation, resulting in a swollen appendix filled with pus, which can progress to tissue death and rupture if left untreated.

• The exact reason for the blockage is unclear, but risk factors include age, family history, and having cystic fibrosis.
• A diet low in fiber may contribute to the development of blockages by promoting harder stool formation.
• The progression from blockage to severe inflammation can happen rapidly, usually within 24-72 hours, making urgent medical attention and surgical removal of the appendix necessary to prevent life-threatening complications like peritonitis.

Pathophysiology

The natural history of appendicitis has been described in three stages: a normal appendix, uncomplicated acute appendicitis, and complicated appendicitis, according to their macroscopic and microscopic appearance and clinical relevance 1.

• The high morbidity and occasional mortality associated with acute appendicitis are related to delay in presentation by patients or delay in diagnosis by the clinician.
• Delays may result in complications like gangrene, perforation, appendiceal mass, and peritonitis, which can prolong hospital stay and increase the cost of treatment.

Clinical Presentation

The clinical presentation of appendicitis is often inconsistent, and diagnostic scoring systems, such as the Alvarado score and the appendicitis inflammatory response (AIR) score, have been developed to provide clinical probabilities of acute appendicitis 1.

• These scoring systems can contribute to diagnosis and help identify patients who require urgent medical attention.
• The development of these scores may also help reduce delays in diagnosis and treatment, ultimately improving patient outcomes.

From the Research

Causes of Acute Appendicitis

• Obstruction of the appendiceal lumen is the main cause of acute appendicitis, which can be due to various factors such as:
  • Fecaliths 2
  • Lymphoid hyperplasia 3, 4, 5, 2
  • Parasites 4
  • Tumors 3, 5, 2
  • Foreign bodies, including seeds 6, 4 and other objects 6
• External compression of the appendix can also lead to outflow obstruction and cause appendicitis, as seen in a case where a thick, adhesive band compressed the base of the appendix 3
• Other potential causes of appendicitis include caecal carcinoma 2 and blunt foreign bodies that can remain dormant for longer periods and cause appendicitis through obstruction of the appendiceal lumen 6