## **Core Concept**
MacEwen's sign, also known as the "MacEwen sign" or "splenic percussion sign," is a clinical examination technique used to assess for **spleen enlargement** or **splenomegaly**. It involves percussion of the left upper quadrant of the abdomen to evaluate the presence and size of the spleen.

## **Why the Correct Answer is Right**
The correct answer, **D. Splenomegaly**, is right because MacEwen's sign is specifically used to detect **splenomegaly**. When the spleen is enlarged, it can be felt or percussed during a physical examination. The test involves the patient lying down, and the examiner performing percussion over the splenic area. A **splenic notch** can sometimes be felt or percussed, which is indicative of an enlarged spleen.

## **Why Each Wrong Option is Incorrect**
- **Option A:** This option is incorrect because MacEwen's sign is not primarily associated with **liver enlargement**. While liver enlargement (hepatomegaly) can cause similar symptoms or findings in the abdomen, MacEwen's sign specifically targets the spleen.
- **Option B:** This option is incorrect as there is no widely recognized association of MacEwen's sign with **ascites**. Ascitic fluid accumulation in the abdomen might alter percussion notes but does not directly relate to the assessment of spleen size.
- **Option C:** This option is incorrect because MacEwen's sign does not assess **intestinal obstruction**. Intestinal obstruction would present with different clinical features such as abdominal pain, vomiting, and constipation or diarrhea.

## **Clinical Pearl / High-Yield Fact**
A key clinical pearl is that a **positive MacEwen's sign** suggests **splenomegaly**, which can be due to various causes including infections (e.g., malaria), liver diseases (e.g., cirrhosis), hematological disorders (e.g., leukemia), and others. It's essential to follow up a positive finding with further diagnostic tests.

## **Correct Answer: D. Splenomegaly**