**Question:** For hiatus hernia, investigation of choice is

A. Barium swallow
B. Upper gastrointestinal endoscopy
C. Ultrasound
D. Computed tomography (CT) scan

**Correct Answer:** A. Barium swallow

**Core Concept:** Hiatus hernia is a gastrointestinal disorder characterized by the upward displacement of the stomach through the diaphragmatic hiatus into the chest cavity.

**Why the Correct Answer is Right:** A barium swallow is the investigation of choice for diagnosing hiatus hernia because it visualizes the gastrointestinal tract and allows for the identification of the herniated stomach. Barium, a chalky substance, coats the gastrointestinal tract, making it visible on X-ray. When a patient with suspected hiatus hernia undergoes a barium swallow, the presence of the herniated stomach can be easily detected as a "double-contrast" or "contrast pooling" sign.

**Why Each Wrong Option is Incorrect:**

**Option B (Upper gastrointestinal endoscopy):** Though endoscopy can visualize the esophagus, stomach, and part of the duodenum, it cannot directly visualize the diaphragmatic hiatus. Hiatus hernia is not directly visible using endoscopy.

**Option C (Ultrasound):** Ultrasound is not the ideal investigation for diagnosing hiatus hernia due to its limited visualization of the gastrointestinal tract and lack of sensitivity in detecting small or sliding hernias. Hiatus hernia can be missed during ultrasound examination.

**Option D (Computed tomography scan):** While CT scan can provide detailed images of the anatomy, it is typically more expensive, time-consuming, and exposes the patient to ionizing radiation. Barium swallow is a simpler and safer alternative that is more commonly available and cost-effective.

**Core Concept (Hiatus hernia):** Hiatus hernia is a common gastrointestinal disorder involving the upward displacement of the stomach through the diaphragmatic hiatus into the chest cavity.

**Why the Correct Answer (Barium swallow) is Right:** Barium swallow serves as the preferred investigation due to its ease of access, cost-effectiveness, and ability to visualize the gastrointestinal tract, including the diaphragmatic hiatus, making it suitable for detecting the herniated stomach and confirming the diagnosis of hiatus hernia.

**Clinical Pearls:** Hiatus hernia is commonly associated with symptoms like heartburn, regurgitation, and chest pain. Diagnosis involves the identification of the "double-contrast" or "contrast pooling" sign on X-ray images obtained after the administration of barium. This sign is indicative of the herniation of the stomach into the chest due to the abnormal opening of the esophagus at the diaphragm.

**Why Each Wrong Option is Incorrect:**

**Option B (Upper gastrointestinal endoscopy):** Although endoscopy can visualize the esophagus and stomach, it cannot directly visualize the diaphragmatic hiatus. Endoscopy primarily evaluates the mucosal abnormalities