Which of the following is the most sensitive clinical sign for acute appendicitis?

Explanation

## Clinical Signs of Acute Appendicitis **Key Point:** McBurney point tenderness is the most sensitive clinical sign for acute appendicitis, present in the majority of patients with confirmed disease. ### McBurney Point Anatomy and Sensitivity The McBurney point is located at the junction of the lateral and middle thirds of a line drawn from the anterior superior iliac spine to the umbilicus. This corresponds to the typical location of the appendiceal base in most individuals. **High-Yield:** McBurney point tenderness has a sensitivity of approximately 85–90% in acute appendicitis, making it the single most reliable physical examination finding. ### Comparison of Clinical Signs | Clinical Sign | Sensitivity | Specificity | Clinical Utility | |---------------|-------------|-------------|------------------| | McBurney point tenderness | 85–90% | 60–70% | Highest sensitivity; present early | | Rebound tenderness | 60–75% | 75–85% | Indicates peritoneal irritation; late sign | | Rovsing sign | 50–60% | 80–90% | Good specificity; less sensitive | | Guarding | 40–50% | 70–75% | Late sign; indicates peritonitis | ### Clinical Pearl **Clinical Pearl:** McBurney point tenderness appears early in the course of appendicitis and may be present even before systemic signs develop. Rebound tenderness and guarding are later signs indicating peritoneal involvement and suggest possible perforation. **Mnemonic:** **MARS** — McBurney point (Sensitivity), Absolute rebound (Specificity), Rovsing (Specificity), Systemic signs (late). [cite:Harrison 21e Ch 297]