What is the recommended screening for a newborn with Down syndrome delivered 2 days ago?

Recommended Screening for Newborn with Down Syndrome at 2 Days of Age

The correct answer is C: Observe meconium passage within 24-48 hours, as this is the critical screening window for detecting gastrointestinal anomalies, particularly Hirschsprung disease, which occurs in 5% of Down syndrome patients and requires urgent intervention to prevent mortality from bowel obstruction. 1

Rationale for Meconium Passage Monitoring

Critical Timing Window

• Healthy full-term newborns pass meconium by 24 hours in 95-96% of cases and by 48 hours in 99.8% of cases 2
• Failure to pass meconium beyond 24 hours warrants close observation, and beyond 48 hours requires investigation for congenital gastrointestinal abnormalities 2
• This timeline is particularly critical in Down syndrome given the 5% prevalence of gastrointestinal anomalies including duodenal atresia and Hirschsprung disease 1

Why This Takes Priority Over Other Options

Option A (Serial abdominal x-rays for other atresias): While gastrointestinal anomalies occur in 5% of Down syndrome cases 1, duodenal atresia typically presents with bilious vomiting and feeding intolerance within the first 24-48 hours, not requiring serial imaging unless clinically indicated. Non-duodenal atresias are not specifically elevated in Down syndrome to warrant routine serial screening.

Option B (Serial ultrasound for pyloric stenosis): Pyloric stenosis is not a recognized association with Down syndrome and typically presents at 3-6 weeks of age, making this inappropriate screening at 2 days of life.

Option D (Fecal calprotectin for necrotizing fasciitis): This option contains a fundamental error—fecal calprotectin is not used for necrotizing fasciitis (a soft tissue infection). If this meant necrotizing enterocolitis (NEC), this condition primarily affects premature infants and is not a specific screening indication for term Down syndrome newborns.

Comprehensive Initial Evaluation Framework

Immediate Priority Assessments (First 48 Hours)

Cardiac evaluation:

• Echocardiography is the single most critical screening test, as 40% of Down syndrome infants have congenital heart disease 3, 4
• This directly impacts mortality and requires urgent identification for surgical planning

Hematologic screening:

• Complete blood count to detect transient myelodysplasia of the newborn 3
• Establishes baseline given 20-fold increased leukemia risk 1

Gastrointestinal monitoring:

• Active observation for meconium passage within 24-48 hours 2
• Monitor feeding tolerance for signs of duodenal atresia (bilious vomiting, feeding intolerance) 1

Diagnostic Confirmation

• Karyotype analysis if not completed prenatally to confirm diagnosis and identify chromosomal mechanism (free trisomy 21 in 95%, translocation, or mosaicism) 3
• This information is essential for genetic counseling regarding recurrence risk 3

Common Pitfall to Avoid

The most dangerous error is assuming that absence of obvious symptoms means absence of serious pathology. In Down syndrome, congenital heart disease may be asymptomatic initially but life-threatening, and delayed meconium passage may be the only early sign of Hirschsprung disease requiring urgent surgical intervention. Both conditions directly impact mortality if missed.