What is the investigation of choice for Hirschsprung's disease?

The investigation of choice for Hirschsprung's disease is a rectal biopsy. This condition is characterized by the absence of ganglion cells in the rectum and proximal colon, leading to a lack of peristalsis and resulting in intestinal obstruction. A rectal biopsy effectively confirms the diagnosis by allowing for histological examination of the tissue. The absence of ganglion cells, specifically the myenteric and submucosal plexuses, indicates Hirschsprung's disease.

While X-ray imaging can be used to assess for bowel obstruction, it does not provide the definitive diagnosis needed for this disease. A CT scan of the abdomen may help visualize the bowel but also cannot confirm the absence of ganglion cells. Endoscopic examination can be useful in evaluating the intestinal lining but does not provide the tissue sample necessary to diagnose Hirschsprung's disease definitively. Thus, the rectal biopsy remains the gold standard in diagnosing this condition.