Failure to pass meconium within 48 hrs of birth in a newborn with no obvious external abnormality should lead to the suspicion of –
Anal atresia
Congenital pouch colon
Congenital aganglinosis
Meconium ileus
Read what Nelson says about Hirschsprung's disease (Congenital aganglionosis).
"Ninety-nine per cent of full-term infants pass meconium within 48hrs of birth. Hirschsprung disease should be suspected in any fill term infant with delayed passage of stool".