**Core Concept**
Ileal atresia is a congenital defect characterized by an obstruction of the ileum, leading to bowel dilatation proximal to the atresia. Radiological findings play a crucial role in diagnosing this condition. In ileal atresia, the bowel proximal to the obstruction becomes dilated, while the bowel distal to the obstruction remains small.

**Why the Correct Answer is Right**
The characteristic radiological finding in ileal atresia is the **"Coil spring appearance"** on a barium enema. This occurs due to the segmental dilatation of the colon proximal to the ileal atresia, which results in a characteristic coiled or spring-like appearance on imaging. The dilated colon segments are separated by narrow, non-dilated segments, resembling a coil spring. This appearance is a result of the abnormal bowel dynamics and the obstruction caused by the ileal atresia.

**Why Each Wrong Option is Incorrect**
* **Option A:** Microcolon on Ba enema is typically seen in cases of intestinal obstruction due to other causes, such as meconium ileus, where the colon is underdeveloped and appears small.
* **Option B:** Double bubble sign is characteristic of duodenal atresia, not ileal atresia, and is seen on abdominal X-rays or ultrasound as two distinct gas-filled structures representing the stomach and duodenum proximal to the atresia.
* **Option D:** Obstruction in Ba meal is a non-specific finding that can be seen in various conditions, including ileal atresia, but is not a unique or diagnostic feature of this condition.

**Clinical Pearl / High-Yield Fact**
In cases of suspected ileal atresia, a contrast enema should be performed to evaluate the colon and identify the characteristic coil spring appearance, which is a key diagnostic feature of this condition.

**Correct Answer:** C. Coil spring appearance in Ba-Enema