## Most Common Cause of Acute Appendicitis **Key Point:** Fecalith impaction is the single most common identifiable cause of acute appendicitis, accounting for approximately 40–50% of cases where a cause is found. ### Mechanism of Obstruction Fecaliths are hard, stone-like masses of inspissated feces and mucus that lodge within the appendiceal lumen. This obstruction: 1. Increases intraluminal pressure 2. Impairs mucosal blood flow 3. Promotes bacterial overgrowth and translocation 4. Leads to inflammation, suppuration, and potential perforation ### Epidemiology & Clinical Significance | Feature | Details | |---------|----------| | **Frequency** | 40–50% of appendicitis cases with identifiable cause | | **Age group** | Peak incidence 10–30 years | | **Pathology** | Visible as hard, yellowish mass in resected specimen | | **Outcome** | Associated with higher perforation risk if diagnosis delayed | **High-Yield:** While many cases of appendicitis have no identifiable cause (idiopathic), when a cause IS found, fecalith is the most frequent culprit. This is a classic NEET PG recall question. **Clinical Pearl:** The presence of a fecalith on imaging (CT or plain film) is a strong predictor of appendicitis and supports urgent surgical intervention. ### Why Other Options Are Less Common - **Lymphoid hyperplasia:** Second most common cause (~30%), especially in children and young adults following viral illness; however, less frequent than fecalith overall. - **Carcinoid tumor:** Rare cause (<1%); typically found incidentally on histology; usually does not cause acute obstruction. - **Crohn's disease:** Uncommon cause of appendicitis; when present, usually associated with terminal ileal involvement and chronic symptoms rather than acute presentation. [cite:Sabiston Textbook of Surgery 21e Ch 50]
Sign up free to access AI-powered MCQ practice with detailed explanations and adaptive learning.