Differential diagnosis of low bowel obstruction in newborn / failure to pass meconium

Approach to the differential diagnosis of low bowel obstruction in the newborn / failure to pass meconium via the appearance of enema

  • Anal atresia – enema cannot be done
  • Colonic atresia – microcolon that is shortened in length, cannot reflux terminal ileum
  • Hirschsprung disease – not a microcolon, rectosigmoid inversion with narrowing extending from rectum up to transition zone, may be unremarkable in newborn
  • Ileal atresia – microcolon without meconium pellets, cannot reflux terminal ileum
  • Meconium ileus – microcolon with meconium pellets, reflux into dilated distal ileum
  • Meconium plug – not a microcolon, caliber of left colon smaller than that of rest of colon
  • Meconium obstruction of prematurity – only seen in extreme prematurity, not a microcolon, multiple plugs of meconium in colon and small bowel