DDX of newborn with low bowel obstruction / failure to pass meconium

Approach to the DDX 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
  • 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