Radiologic feature suggestive of Achalasia cardia is-
**Core Concept**
Achalasia cardia is a motility disorder of the esophagus characterized by the failure of the lower esophageal sphincter (LES) to relax, leading to difficulty swallowing and regurgitation of food. The primary pathophysiological mechanism involves impaired esophageal peristalsis and abnormal relaxation of the LES.
**Why the Correct Answer is Right**
The characteristic radiologic feature of achalasia cardia is the "bird's beak" appearance on barium swallow studies. This occurs due to the failure of the LES to relax, resulting in a narrow tapering of the distal esophagus. The "bird's beak" appearance is a result of the combination of impaired peristalsis and the inability of the LES to relax, causing the distal esophagus to become compressed and taper towards the stomach.
**Why Each Wrong Option is Incorrect**
**Option A:** A "rat tail" appearance is more characteristic of esophageal carcinoma, which causes a more pronounced narrowing of the esophagus.
**Option B:** A "sigmoid" esophagus is seen in diffuse esophageal spasm, a condition characterized by abnormal peristalsis and not by the failure of the LES to relax.
**Option C:** A "corkscrew" esophagus is seen in esophageal scleroderma, which causes fibrosis and narrowing of the esophagus, but not by the failure of the LES to relax.
**Clinical Pearl / High-Yield Fact**
Achalasia cardia is often associated with a "bird's beak" appearance on barium swallow studies, which is a classic radiologic feature that should prompt further investigation and diagnosis.
**Correct Answer:** C.