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MECONIUM ILEUS OBSTRUCTION IN NEWBORN
Category: Child Health
Abstract : Meconium ileus: Meconium ileus is the term used to describe neonatal
presentation of distal small-bowel obstruction from thickened meconium in
patients with cystic fibrosis. Meconium ileus is the earliest manifestation of
cystic fibrosis in the newborn period. Cystic fibrosis is an autosomal recessive
condition characterized by abnormalities in cellular membrane physiology and
chlorid
Meconium ileus:
Meconium ileus is the term used to describe neonatal
presentation of distal small-bowel obstruction from thickened meconium in
patients with cystic fibrosis. Meconium ileus is the earliest manifestation of
cystic fibrosis in the newborn period.
Cystic fibrosis is an autosomal recessive
condition characterized by abnormalities in cellular membrane physiology and
chloride ion transport that contribute to progressive respiratory failure,
derangements in cellular secretory patterns, and diminished mucosal motility.
Incidence of cystic fibrosis is 1 case per 3000 live births. Of newborns with
cystic fibrosis, 10-20% present with meconium ileus.
The gene for cystic
fibrosis is carried by 3.3% of whites. Identified in 1985, the cystic fibrosis
gene localized to the DF508 locus on chromosome 7 codes for a protein that acts
as a cystic fibrosis transmembrane conductance regulator (CFTCR). Abnormalities
in the CFTCR disrupt membrane function. In the GI mucosa of the newborn, this
defect manifests as poor motility. Meconium may build up and obstruct the lumen
of the distal small bowel and colon. Because meconium does not pass readily into
the distal GI tract, distal small-bowel obstruction may develop in utero. The
involved segment of bowel may dilate and even perforate. A pseudocyst may wall
off around the perforation. Prenatal ultrasonography or neonatal plain
radiography may identify a soap bubble or ground glass appearance of inspissated
meconium. Adhesions may develop from the perforation. The functional picture of
tenacious thick meconium that does not pass is termed meconium
ileus.
Segmental obstruction of the small bowel from meconium ileus can
also precipitate volvulus of the bowel upstream from the obstruction. Treatment
of meconium ileus involves evacuation of the meconium. In more than 50% of
patients, nonsurgical management relieves the obstruction successfully.
A
contrast enema may be both diagnostic and therapeutic. For the enema to evacuate
the meconium, fluid must be refluxed into the terminal ileum. Multiple enemas
may be administered. Dilute Gastrografin with N-acetylcysteine may be
administered by nasogastric tube from above to help loosen the meconium.
Hyperosmolar solutions (1% acylcysteine) may be effective in drawing more fluid
into the lumen of the bowel, thereby enhancing the ability to loosen the thick
meconium.
Hyperosmolar enemas may increase the risk of perforation. The
risk of perforation reportedly is 3-10%. Calcification on scout radiography
suggests intrauterine perforation. Do not administer therapeutic contrast enemas
in the presence of bowel perforation or compromise. A pseudocyst may develop
around a bowel perforation during development. In these patients or in those who
underwent unsuccessful initial management with enemas, postnatal laparotomy is
indicated. An enterotomy with irrigation of the bowel contents may move the
meconium through successfully. In some patients, an ostomy for diversion and
access for proximal irrigation may be necessary. Long-term outcome depends upon
management of the underlying cystic fibrosis.
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