What is the most common cause of acute appendicitis?

The most common cause of acute appendicitis is fecalith obstruction. Appendicitis often occurs when the lumen of the appendix becomes blocked, which can lead to an increase in intraluminal pressure, compromised blood flow, and bacterial proliferation. Fecaliths, which are hardened fecal matter that can obstruct the opening of the appendix, are the primary culprits in this blockage. When a fecalith obstructs the appendix, it creates an environment conducive to bacterial infection, resulting in inflammation and the symptoms associated with appendicitis.

Other causes, such as viral infections, foreign bodies, or malignancies, are much less common in causing acute appendicitis. Viral infections may cause inflammation but are not typically responsible for appendiceal obstruction. Foreign bodies are rare causes, while malignancies are usually seen in older patients and account for a very small percentage of appendicitis cases. Thus, fecalith obstruction stands out as the most prevalent etiology for acute appendicitis.