**Question:** A 4-year-old boy presents with a history of constipation since the age of 6 months. His stools, produced every 3 to 4 days, are described as large and hard. His growth velocity is normal. Physical examination is normal; rectal examination reveals a large ampulla, poor sphincter tone but present anal wink, and stool in the rectal vault. The plain film of his abdomen is shown. Which of the following is the most appropriate next step in the management of this child?

A. Medical therapy (e.g., laxatives)
B. Surgery (e.g., posterior sagittal anorectoplasty)
C. Dietary modifications
D. Nutritional assessment

**Correct Answer:** B. Surgery (e.g., posterior sagittal anorectoplasty)

**Core Concept:** Hirschsprung disease is a congenital disorder characterized by the absence of ganglion cells in the distal colon, leading to impaired colonic motility and constipation.

**Why the Correct Answer is Right:**

In this case, the child presents with constipation since the age of 6 months, characterized by the presence of large, hard stools, poor sphincter tone, and the presence of stool in the rectal vault on rectal examination. The child's growth velocity is normal, which suggests that the constipation is not due to nutritional deficiency. The plain film of the abdomen shows no abnormalities, ruling out other causes like intestinal obstruction.

Given these clinical findings, the most appropriate next step in the management of this child is to consider surgery (option B) as the child likely has Hirschsprung disease, a congenital disorder characterized by the absence of ganglion cells in the distal colon. This results in impaired colonic motility and constipation. Surgery, specifically posterior sagittal anorectoplasty, is needed to address the obstruction caused by the aganglionic segment and restore bowel continuity.

**Why Each Wrong Option is Incorrect:**

A. Medical therapy (option A) with laxatives may provide temporary relief but does not address the underlying structural abnormality causing the constipation in this case. Medical therapy alone would not resolve the aganglionic segment and its impact on colonic motility.

C. Dietary modifications (option C) may help improve bowel habits but do not treat the underlying structural abnormality caused by the aganglionic segment. Addressing dietary modifications without surgical intervention would not resolve the impaired colonic motility in this case.

D. Nutritional assessment (option D) is essential in evaluating patients with constipation for malnutrition, electrolyte imbalance, or other nutritional causes. In this case, the child's growth velocity is normal, suggesting that nutritional assessment is not the primary concern.

**Clinical Pearls:**

1. Hirschsprung disease is a common cause of constipation in infants and children.
2. Surgery, like posterior sagittal anorectoplasty, is the definitive treatment for Hirschsprung disease, as it addresses the obstructed segment and restores bowel continuity.