**Question:** Investigation for small intestine includes all except:

A. Abdominal X-ray
B. Colonoscopy
C. CT scan
D. Barium meal

**Core Concept:**
The small intestine is a crucial part of the digestive system, where most nutrient absorption occurs. In clinical practice, various investigations are used to diagnose conditions affecting the small intestine. These investigations should be specific to target the small intestine and not involve procedures that are predominantly used for other parts of the gastrointestinal tract or body in general.

**Why the Correct Answer is Right:**
The correct answer is **A. Abdominal X-ray**. An abdominal X-ray is a general radiological examination of the abdomen, including the small intestine, and is not specific to the small intestine. Thus, it is an inappropriate investigation for diagnosing small intestine-related issues.

**Why Each Wrong Option is Incorrect:**

**B. Colonoscopy:** A colonoscopy is a procedure used to examine the colon, rectum, and sometimes the beginning of the small intestine (ileum). It is not suitable for investigating the majority of the small intestine.

**C. CT scan:** A computed tomography (CT) scan is a cross-sectional imaging technique used to visualize various organs and structures, including the abdomen and pelvis. While it may occasionally provide information about the small intestine, it is not a dedicated investigation for small intestine disorders.

**D. Barium meal:** A barium meal is a diagnostic procedure involving the ingestion of a barium-based contrast medium to visualize the gastrointestinal tract on X-ray. This investigation is primarily used for the large intestine (colon) and small bowel imaging, but it is not suitable for investigating the stomach and upper gastrointestinal tract.

**Clinical Pearl:**
Investigating small intestine disorders requires specific procedures, such as small bowel imaging techniques like enteroclysis or enterography with barium or CT contrast medium. These procedures aim to visualize the small intestine and are more appropriate for diagnosing small intestine-related issues compared to the options provided.