MECONIUM PLUG SYNDROME

Meconium plug syndrome / Left hypoplastic colon syndrome : Colonic obstruction in the newborn child could be the result of necrotizing enterocolitis, atresia, meconium plug syndrome, duplication cyst, Hirschsprung disease or the small left colon syndrome. In meconium plug syndrome the baby expels a grey-meconium and the obstruction subsides. Meconium plug syndrome (MPS) was first described by Clatworthy in 1956 as a transient form of distal colonic or rectal obstruction in newborns caused by an inspissated, immobile meconium. The plug is white and chalky and rarely involves the small bowel.

Clinical manifestations include progressive abdominal distension, vomiting (sometimes is bilious) and failure to pass meconium during the initial two days of life. Though most cases are idiopathic, Meconium plug syndrome has been associated with prematurity, hypotonia, hypermagnesemia (reduces acetylcholine release with subsequent myoneural depression), diabetic mother, Hirschsprung’s disease and cystic fibrosis. Colonic contrast study suggests the diagnosis (filling defect) and can be therapeutic in most cases to relieve the obstruction. Gastrografin instillation is highly effective in moving the obstructing long, thick plug, even in tiny premature infants with Meconium plug syndrome. Suction rectal biopsy to exclude the diagnosis of Hirschsprung’s disease along with cystic fibrosis screening is warranted in all cases of MPS. The diagnosis of MPS is made after all the above causes are excluded. Need for surgery is extremely rare.

The left (small) hypoplastic colon syndrome (LHCS) is a very rare cause of colonic obstruction
identified in newborns with characteristic roentgenographic features resembling those of Hirschsprung's
disease. Manifesting in the first 24-48 hours of life, LHCS is a functional disturbance related to immaturity of the intrinsic innervation of the colon that is especially common in low birth weight neonates or of diabetic mothers. Intestinal perforation, sepsis, hypoglycemia and death may occur. The diagnosis is suggested in a barium enema when the caliber of the left colon is small with a transitional zone at the splenic flexure. Management consists of hypoglycemia correction, antibiotics, nasogastric decompression and observation. In most babies the obstruction clears in 48-72 hours. When the clinical diagnosis is not readily apparent a rectal biopsy and sweat chloride test should be done to differentiate LHCS from Hirschsprung disease and cystic fibrosis respectively. The narrowed left colon remains narrow in follow-up.