<prompt> The diagnosis of congenital megacolon is confirmed byClinical featuresBarium enemaRectal biopsyRecto-sigmoidoscopy  <response>: -Biopsy from all three zones to study the ganglions and hyperophic nerve terminals in spasmodic segment. Staing from 2 cm above the dentate line, a full thickness rectal biopsy is ideal. Barium enema is done to look for the extent of disease and three zones. Foleys catheter should not be used while doing barium enema in case of Hirschsprungs disease Anorectal manometry--shows the absence of rectoanal reflex in Hirschsprungs disease, which is diagnostic. Acetylcholine esterase staining shows hyperophied nerve bundles. ref:SRB ;s manual of surgery,ed 3,pg no-819 