<prompt> The diagnosis of congenital megacolon is confirmed by -Clinical featuresBarium enemaRectal biopsyRecto-sigmoidoscopy  <response>: C Rectal biopsy 122 - Bailey and Love 26thDiagnosis of Hirschsprungs disease Cong. MegacolonDigital examination: On digital examination rectum is empty Rapid expulsion of faeces often follows examination Contracted rectal wall can sometimes be appreciated by examining finger.Anorectal manometry:measure the pressure when balloon is distended in rectum. Normal individual - Reflex decline in internal sphincteric pressure. Hirschsrungs disease - Pressure fails to drop, paradoxical rise in pressure with rectal distention.Radiography Barium enema: demonstrates presence of transition zone which lies between normal dilated proximal colon and a smaller caliber obstructed distal colon.Rectal biopsy:It is the definitive diagnostic procedure in hirschsprungs disease, it demonstrates. Hypertrophied nerve bundles Absence of ganglion cells Commonest cause colonic obstruction in neonates. Chronic constipation ? not large stool. Males, starting in first few weeks of life. Loud borboygri because of intestinal obstruction. Fecal soiling is not a feature.Causes of Acquired Megacolon: Chagas disease caused by protozoan - Trypanoma-cruzi. Secondary to medications anticholinergics Neurological disorders Paraplegia, poliomyelitis motor neuron disease, multiple sclerosis Rectal cancer Defective migration of neural crest cells results. Albinism Cong, megacolon Melanoma Oropharyngeal teratoma Elephant man Neurocristopathies. 