How is the diagnosis of Hirschsprung disease confirmed via imaging?

• A. CT scan
• B. Abdominal X-ray showing megacolon
• C. Ultrasound
• D. Magnetic resonance imaging (MRI)

Answer: (B)

The diagnosis of Hirschsprung disease is often confirmed by imaging findings that highlight the characteristic features of this condition. In particular, an abdominal X-ray can show signs of megacolon, which is a hallmark of Hirschsprung disease. This results from a lack of ganglion cells in the distal colon, leading to functional obstruction. The proximal bowel becomes distended while the affected distal segment remains narrow, often leading to significant dilation of the proximal bowel, which can be visualized on X-rays.

Megacolon seen on the X-ray is a crucial diagnostic clue, and it helps differentiate Hirschsprung disease from other causes of bowel obstruction. This imaging modality is particularly useful because it is straightforward, non-invasive, and quick, allowing for an efficient assessment of bowel distension.

Other imaging modalities such as CT scans and MRIs are not routinely used for diagnosing Hirschsprung disease, as they are more complex and may not provide the specific information needed to confirm the diagnosis. Ultrasound can be helpful in certain cases for evaluating bowel structure but does not provide the same clarity about prolonged distension and megacolon associated with Hirschsprung disease as does an abdominal X-ray. This is why an abdominal X-ray showing megacolon is considered a key