What is the primary method used to diagnose Hirschsprung's disease?

The primary method used to diagnose Hirschsprung's disease is through a rectal biopsy. This condition, which arises from the absence of ganglion cells in a segment of the bowel, leads to an inability to relax that segment, resulting in obstruction and constipation. By obtaining a rectal biopsy, healthcare providers can identify the absence of enteric ganglia, which confirms the diagnosis. The biopsy provides direct evidence of the underlying pathology, making it the gold standard for diagnosing Hirschsprung's disease.

Other methods such as ultrasound, X-ray with contrast, and MRI may provide supportive information regarding bowel distension or the presence of obstructions, but they do not establish the definitive diagnosis. The rectal biopsy uniquely identifies the absence of the necessary nerve cells and provides vital information about the degree and location of the affected bowel segment, which is crucial for planning appropriate treatment.