- Ileal atresia
- Meconium ileus
- Meconium plug syndrome
- Meconium obstruction of prematurity
- Hirschsprung disease
- Colonic atresia
- Anorectal malformation
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 in length
- 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
