Double bubble appearance in plain X-ray is seen in :
**Core Concept**
The double bubble appearance in a plain X-ray is a radiological sign indicative of intestinal obstruction, specifically duodenal obstruction. It is characterized by two distinct air-filled structures, which are usually the stomach and the duodenum, visible above the diaphragm.
**Why the Correct Answer is Right**
The double bubble sign is caused by the accumulation of air in the stomach and the duodenum due to an obstruction, which prevents the normal flow of intestinal contents. This obstruction can be due to various causes, such as duodenal atresia, duodenal stenosis, or pyloric stenosis. The air in the stomach and duodenum creates two distinct bubbles, which are visible on the X-ray, giving it the characteristic double bubble appearance.
**Why Each Wrong Option is Incorrect**
**Option A:** This option is incorrect because the double bubble sign is specific to intestinal obstruction, and the other options listed (e.g., appendicitis, cholecystitis) do not typically present with this radiological feature.
**Option B:** This option is incorrect because the double bubble sign is not typically associated with small bowel obstructions distal to the duodenum, such as those caused by intussusception or volvulus.
**Option C:** This option is incorrect because the double bubble sign is not a characteristic finding in conditions that primarily affect the colon, such as colon cancer or diverticulitis.
**Clinical Pearl / High-Yield Fact**
The double bubble sign is a classic radiological finding in duodenal obstruction, and it is often seen in infants and children. It is essential to recognize this sign and differentiate it from other causes of abdominal distension to provide prompt and effective treatment.
**Correct Answer: D. Duodenal atresia.**