**Question:** How will you confirm Hirschsprung's disease:

A. Biopsy of the affected area
B. Barium enema
C. Fecal fat study
D. Colonoscopy with biopsy

**Correct Answer:** D. Colonoscopy with biopsy

**Core Concept:** Hirschsprung's disease is a congenital disease affecting infants, characterized by the absence of ganglion cells in the distal colon, leading to الإمساك and distension.

**Why the Correct Answer is Right:**
Colonoscopy with biopsy is the gold standard for diagnosing Hirschsprung's disease. During colonoscopy, the distal colon and rectum are examined for any abnormalities. If the disease is suspected, a biopsy is taken from the affected area. Histopathological examination of the biopsy sample confirms the absence of ganglion cells, which confirms the diagnosis of Hirschsprung's disease.

**Why Each Wrong Option is Incorrect:**

A. Biopsy of the affected area (option A) is partially correct, but the gold standard is a combination of colonoscopy with biopsy, as it allows for direct visualization of the affected area and confirmation through histopathology.

B. Barium enema (option B) is used to visualize the colon, but it does not provide direct evidence of ganglion cell absence, which is crucial for diagnosing Hirschsprung's disease.

C. Fecal fat study (option C) is used to assess malabsorption but does not confirm the absence of ganglion cells, which is essential for making the definitive diagnosis of Hirschsprung's disease.

**Clinical Pearl:**
Colonoscopy with biopsy is critical for the definitive diagnosis of Hirschsprung's disease since it allows for direct visualization of the affected area, confirmation through histopathology, and exclusion of other differential diagnoses.