**Question:** When the rectum is inflated with air through a rectal tube, pain and tenderness occur in the right iliac fossa in case of appendicitis. This is known as-

A. Rebound tenderness
B. Proteus mirabilis infection
C. Gas in the cecum
D. Stomach distension

**Correct Answer:** A. Rebound tenderness

**Core Concept:** Appendicitis is an inflammation of the appendix, a vermiform tubular structure located at the cecum, the terminal part of the large intestine. This condition can present with right lower quadrant abdominal pain, fever, and rebound tenderness.

**Why the Correct Answer is Right:** When a rectal tube is used to inflate the rectum with air, it can cause local pain and tenderness due to the pressure applied to the surrounding structures. In the context of appendicitis, this can lead to the identification of rebound tenderness, a significant physical finding indicating inflammation and potential obstruction of the appendix.

**Why Each Wrong Option is Incorrect:**

**Option B (Proteus mirabilis infection):** Proteus mirabilis is a bacterium commonly found in the gastrointestinal tract. While infection can lead to abdominal pain, it is not specifically associated with right lower quadrant tenderness or rebound tenderness.

**Option C (Gas in the cecum):** Gas in the cecum, although causing right lower quadrant pain, is not typically associated with rebound tenderness. Rebound tenderness is a clinical sign specific to appendicitis.

**Option D (Stomach distension):** Stomach distension is unrelated to right lower quadrant tenderness or rebound tenderness, which are specific to appendicitis.

**Clinical Pearl:** Rebound tenderness is a critical clinical sign in the assessment of patients with suspected appendicitis. It helps differentiate appendicitis from other causes of right lower quadrant pain and guides further diagnostic and therapeutic decisions, such as imaging studies and surgical intervention when necessary.