What causes appendicitis (inflammation of the appendix)?

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From the Guidelines

Appendicitis is primarily caused by a blockage of the appendix, which leads to infection, and this blockage is often due to hardened fecal matter, enlarged lymphoid follicles, or other foreign bodies, as supported by recent guidelines 1. The exact cause of appendicitis can vary, but it typically involves an obstruction of the appendix opening, allowing bacteria to multiply and cause infection.

Common Causes of Blockage

  • Hardened fecal matter
  • Enlarged lymphoid follicles
  • Intestinal worms
  • Trauma to the abdomen
  • Rarely, tumors Once the appendix is blocked, bacteria normally present in the intestines rapidly multiply, causing inflammation, swelling, and pus formation, which can lead to increased pressure, reduced blood flow, and potential tissue death if left untreated 1.

Importance of Prompt Medical Attention

Prompt medical attention is crucial, as a ruptured appendix can cause life-threatening peritonitis.

Symptoms to Watch For

If you experience persistent abdominal pain that begins around your navel and shifts to your lower right abdomen, along with nausea, vomiting, and fever, seek immediate medical care, as these symptoms can indicate appendicitis, and timely intervention is essential to prevent complications, as emphasized in the 2020 update of the WSES Jerusalem guidelines 1.

From the Research

Causes of Appendicitis

The causes of appendicitis, which is the inflammation of the appendix, can be attributed to various factors. Some of the main causes include:

  • Luminal obstruction of the vermiform appendix, leading to ischemia of the appendix wall and subsequent translocation of bacteria across the compromised mucosa, resulting in transmural inflammation 2
  • Hyperplasia of lymphoid tissue in the mucosa, often secondary to infection and inflammation with gradual symptom onset 2
  • Foreign body ingestion, which can cause obstruction of the appendiceal lumen, leading to appendicitis 3, 4
  • Parasitic infiltration, fibrous bands, and carcinoid syndrome, which are rarer causes of obstruction 2
  • External compression of the appendix, leading to outflow obstruction, as seen in a case where a thick, adhesive band compressed the base of the appendix 5

Rare Causes of Appendicitis

Some rare causes of appendicitis include:

  • Ingestion of seeds, which can cause diagnostic challenges and may be mistaken for parasites 6
  • Ingestion of other foreign bodies, such as needles, drill bits, or organic matter, which can remain silent within the appendix for many years without an inflammatory response 3
  • Accidental ingestion of unusual foreign bodies, such as a condom fragment, which can initiate an inflammatory process 4

Mechanism of Appendicitis

The exact mechanism of appendicitis has yet to be fully elucidated, but it is believed that different forms of luminal obstruction of the vermiform appendix lead to ischemia of the appendix wall and subsequent translocation of bacteria across the compromised mucosa, leading to transmural inflammation 2

References

Guideline

Guideline Directed Topic Overview

Dr.Oracle Medical Advisory Board & Editors, 2025

Research

A bizarre foreign body in the appendix: A case report.

World journal of gastrointestinal surgery, 2013

Research

Ischemic appendicitis due to pelvic adhesions: a case report.

Journal of surgical case reports, 2020

Research

A "fruitful" cause of acute appendicitis.

La Tunisie medicale, 2023

Professional Medical Disclaimer

This information is intended for healthcare professionals. Any medical decision-making should rely on clinical judgment and independently verified information. The content provided herein does not replace professional discretion and should be considered supplementary to established clinical guidelines. Healthcare providers should verify all information against primary literature and current practice standards before application in patient care. Dr.Oracle assumes no liability for clinical decisions based on this content.

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