<prompt> True about Hirschsprug;s diseaseAganglionic segment is contracted not dilatedDescending colon is most common siteBarium enema is diagnosticBarium enema shows calcification  <response>: Hirschsprung;s disease : congenital absence of ganglion cells in the submucosal and myentric plexus of distal intestine Rectal biopsy is goldstandard in diagnosing disease. in barium enema,the narrow aganglionic bowel with dilated proximal bowel is seen Symptoms:failure to pass meconium in first 48 hours of life,vomiting,constipation,poor feeding,abdominal distension Ref : ESSENTIAL PEDIATRICS,O.P.GHAI,PG NO:256, 7th edition 