Investigation of choice in hirschsprug's disease is -
Rectal manometry
Rectal examination
Rectal biopsy
Ba enema
Definitive diagnosis is made by rectal biopsy. The histopathology of Hirschprung's disease is the absence of ganglion cells in the nerve plexus, presence of hypertrophied nerve bundles and increased acetykholinesterase-positive nerve fibres.