What is the gold standard for diagnosing Hirschsprung's disease?

The gold standard for diagnosing Hirschsprung's disease is a punch biopsy of the rectal mucosa. This procedure is crucial because it allows for the examination of nerve fibers in the bowel wall. In Hirschsprung's disease, there is an absence of ganglion cells (aganglionosis) in a segment of the colon, typically affecting the rectum and extending proximally. The punch biopsy provides direct tissue sampling, which can confirm the absence of these nerve cells, thus confirming the diagnosis.

While colonoscopy may be used as part of the diagnostic workup, it does not provide the definitive histological evidence needed to diagnose the disease. CT scans and ultrasounds can aid in the evaluation of intestinal obstructions and abnormalities but do not directly diagnose Hirschsprung's disease through histopathology.