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Difficulty: HardPediatric Gastrointestinal Disorders

A 22-day-old full-term male neonate is evaluated in the neonatal intensive care unit for abdominal distension and vomiting. The emesis is dark green. The infant was born via uncomplicated vaginal delivery to a 2828-year-old primigravid woman. The prenatal course was unremarkable. The infant has not passed meconium since birth. His temperature is 37.1∘37.1^\circ C (98.8∘98.8^\circ F), heart rate is 145145/min, respiratory rate is 4242/min, and blood pressure is 65/4065/40 mmHg. Physical examination reveals a markedly distended and firm abdomen. Bowel sounds are absent, and there is no erythema of the abdominal wall. An anteroposterior abdominal radiograph demonstrates multiple dilated loops of small bowel with a distinct lack of air-fluid levels. A bubbly, granular appearance is noted in the right lower quadrant. There is no free air under the diaphragm.

Which of the following is the most appropriate next step in management?

  1. Administration of a water-soluble contrast enemaAnswer
  2. B
    Quantitative sweat chloride testing
  3. C
    Immediate exploratory laparotomy
  4. D
    Suction rectal biopsy
  5. E
    Upper gastrointestinal contrast series

Answer

Administration of a water-soluble contrast enema
The correct answer is the administration of a water-soluble contrast enema. The infant's presentation and pathognomonic radiograph showing a bubbly 'ground-glass' appearance (Neuhauser sign) with an absence of air-fluid levels indicate meconium ileus. A hyperosmolar contrast enema (such as Gastrografin) is both a diagnostic tool that visualizes a microcolon and a therapeutic procedure that draws fluid into the lumen to dissolve the meconium obstruction.

Step-by-Step Solution

1
Analyze the clinical presentation.
The infant has delayed passage of meconium, bilious emesis, and abdominal distension, which are classic signs of a neonatal lower gastrointestinal obstruction.
Identifying the level of obstruction narrows the differential diagnosis to conditions like meconium ileus, Hirschsprung disease, or ileal atresia.
2
Interpret the radiographic findings.
The abdominal X-ray shows dilated small bowel without air-fluid levels and a bubbly right lower quadrant (Neuhauser sign).
Viscid, inspissated meconium does not separate cleanly from swallowed air, preventing the formation of distinct air-fluid levels. The bubbly appearance represents trapped air mixed with thick meconium, heavily pointing to meconium ileus.
3
Determine the appropriate intervention based on the diagnosis.
A hyperosmolar water-soluble contrast enema is selected as the next step.
Unless complicated by perforation or peritonitis, meconium ileus is initially managed non-operatively. The hyperosmolar enema draws fluid into the bowel lumen, breaking down the meconium mass and relieving the obstruction.

Key Concept

Meconium ileus typically presents with a 'ground-glass' appearance on abdominal X-ray without air-fluid levels, and uncomplicated cases should be initially managed with a therapeutic water-soluble contrast enema.
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Topics

Pediatric Gastrointestinal Disorders

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