What is the recommended initial screening for a 2-day-old newborn with Down syndrome to assess for potential gastrointestinal complications?

Recommended Screening for 2-Day-Old Newborn with Down Syndrome

The correct answer is C: Observe meconium passage within 24-48 hours, as this is the most critical initial screening to detect Hirschsprung disease and other gastrointestinal obstructions that occur at significantly higher rates in Down syndrome newborns.

Rationale for Meconium Passage Monitoring

Newborns with Down syndrome have substantially elevated risk for gastrointestinal anomalies that present with delayed meconium passage:

• Hirschsprung disease occurs in 2.76% of infants with Down syndrome (compared to 0.02% in the general population), making it approximately 138 times more common 1
• Duodenal atresia/stenosis affects 3.9% of Down syndrome newborns, which would typically present with bilious vomiting rather than delayed meconium passage 1
• Anorectal malformations occur in 1.16% of this population 1
• Failure to pass meconium within 24-48 hours is a red flag for intestinal obstruction, particularly Hirschsprung disease 2, 3

Why the Other Options Are Incorrect

Serial Abdominal X-rays for Non-Duodenal Atresia (Option A)

• Not indicated as routine screening in an asymptomatic 2-day-old infant 2
• Abdominal imaging is only appropriate when clinical signs of obstruction develop (bilious vomiting, abdominal distension, failure to pass meconium) 4, 2
• Unnecessary radiation exposure without clinical indication 5

Serial Ultrasound for Pyloric Stenosis (Option B)

• Pyloric stenosis presents at 2-8 weeks of age, not at 2 days 6, 5
• The incidence in Down syndrome is only 0.3%, making it an inappropriate screening target in the immediate newborn period 1
• Ultrasound is diagnostic when symptoms develop (projectile non-bilious vomiting, palpable "olive"), not a screening tool 5

Fecal Calprotectin for Necrotizing Fasciitis (Option D)

• This option contains a fundamental error: fecal calprotectin is used for inflammatory bowel disease screening, not necrotizing fasciitis 1
• Neither test is appropriate routine screening for a 2-day-old newborn with Down syndrome
• Necrotizing enterocolitis (likely the intended condition) is not specifically associated with Down syndrome and would present with clinical signs first 3

Clinical Implementation

Practical monitoring approach:

• Document time of first meconium passage - should occur within 24-48 hours of birth 2, 3
• If meconium passage is delayed beyond 48 hours, obtain abdominal X-ray to evaluate for obstruction 2, 3
• Monitor for other signs of obstruction: bilious vomiting, abdominal distension, feeding intolerance 4, 3
• Neonates with unrecognized intestinal obstruction deteriorate rapidly, making early detection critical 2, 3

Additional Considerations for Down Syndrome Newborns

While not part of the immediate 2-day screening question, be aware that:

• Congenital heart disease affects 40% and requires echocardiography screening 7
• Gastrointestinal anomalies overall affect approximately 5% of Down syndrome infants 7, 1
• Early surgical consultation is warranted if any signs of obstruction develop 3