This condition, which accounts for
about 30% of cases of intestinal obstruction
among neonates, is characterized
by the inspissation of thick,
tenacious meconium in the bowel.
The most common cause is cystic fibrosis;
approximately 6% to 20% of infants
with cystic fibrosis have meconium
ileus. Hyperviscous mucus secreted
by abnormal intestinal glands,
an abnormal concentrating process
in the proximal small intestine, and a
deficiency of pancreatic enzymes
have been implicated in the pathogenesis.
The histologic hallmark is distention of the goblet
cells in the intestinal mucosa.
Infants with meconium ileus present with abdominal
distention, bilious vomiting, and failure to pass meconium.
Thickened bowel loops filled with rubbery meconium are
often visible and palpable through the abdominal wall.
Remarkable abdominal distention, abdominal tenderness,
or abdominal erythema indicates perforation.
Meconium ileus may be complicated in up to 50% of
patients by volvulus, intestinal perforation, meconium peritonitis
(A), and ischemic necrosis of the bowel that results
in stenosis or atresia.
The classic radiographic findings are:
- Distended loops of bowel.
- A soap-bubble or ground-glass appearance in the right
lower quadrant that suggests the presence of air in the
meconium (Neuhauser sign).
- A paucity of air-fluid levels on the upright view.
Calcification, free air, or multiple air-fluid levels suggest
intestinal perforation. A contrast enema typically
demonstrates a microcolon and a terminal ileum filled
with pellets of meconium (B).
Uncomplicated meconium ileus may be treated with
a diatrizoate meglumine/diatrizoate sodium enema performed
under fluoroscopic control with concomitant administration
of intravenous fluid. The hyperosmolar agent
draws fluid into the bowel lumen to facilitate passage and
expulsion of meconium. This technique is successful in
50% of uncomplicated cases.
Surgery is required for patients with complicated
meconium ileus and for those in whom nonoperative therapy
has been unsuccessful. Options include enterotomy to
evacuate the meconium, ileostomy at the proximal end of
the obstructed segment, and insertion of a T tube into the
bowel for postoperative irrigation with acetylcysteine.
Complications such as atresia, perforation, and meconium
peritonitis may necessitate bowel resection, intestinal
anastomosis, and ileostomy.