Meconium plug syndrome refers to a functional colonic obstruction in a newborn due to an obstructing meconium plug. It is usually transient and affects the left colon with meconium plugging the bowel distal to this segment. It is also known as small left colon syndrome or functional immaturity of the colon.
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Epidemiology
Associations
may have a higher prevalence with maternal diabetes 2
higher prevalence in infants of mothers who received magnesium sulphate for pre-eclampsia
Hirschsprung disease in ~15% 3
may be associated with cystic fibrosis 3
Radiographic features
Plain radiograph
May show multiple dilated bowel loops which are a non-specific finding. There may be a caliber change around the splenic flexure.
Fluoroscopy
Contrast enema
Contrast enema may demonstrate a small caliber left colon with multiple filling defects within due to retained meconium. The rectum is usually normal in size, unlike Hirschsprung disease. The use of high-osmolar ionic contrast media for enema in a neonate or infant is controversial due to the risks associated with fluid shift 4. The enema can be both diagnostic as well as therapeutic and is usually accompanied by the passage of meconium during or after the procedure.
Treatment and prognosis
Usually resolves with time. Initial non-surgical management includes rectal stimulation and contrast enema 3.
Differential diagnosis
On a plain radiograph consider most other causes of bowel obstruction. On a contrast enema consider:
meconium ileus (usually does not spare the right colon, which is also small caliber)
long segment Hirschsprung disease (often has a reversed rectosigmoid ratio)
ileal atresia (on contrast enema)