What is the most appropriate next step for a newborn with abdominal distention, tenderness upon palpation, absent bowel sounds, and no meconium passage for 48 hours?

Most Appropriate Next Step: Immediate Pediatric Surgical Referral

The most appropriate next step is B - Refer to pediatric surgery immediately, as this newborn presents with peritoneal signs (tenderness and absent bowel sounds) indicating a potential surgical emergency that requires urgent evaluation before any diagnostic imaging studies. 1

Clinical Reasoning

Why Immediate Surgical Consultation Takes Priority

The combination of clinical findings in this case mandates urgent surgical evaluation:

• Absent bowel sounds with abdominal tenderness suggests peritonitis or bowel compromise, which represents a surgical emergency requiring immediate intervention before diagnostic studies 1
• Delayed meconium passage beyond 48 hours with abdominal distention is typical for distal bowel obstruction, which may require urgent surgical intervention 1
• 20% of neonates with bilious vomiting in the first 72 hours have midgut volvulus requiring urgent surgery, and the clinical presentation cannot exclude this life-threatening diagnosis 1

Critical Pitfall to Avoid

Never delay surgical consultation for imaging studies in a neonate with peritoneal signs (tenderness and absent bowel sounds), as this can lead to significant morbidity and mortality. 1 The physical examination findings of tenderness and absent bowel sounds indicate potential bowel ischemia or perforation, which are surgical emergencies that cannot wait for diagnostic confirmation.

Why Not the Other Options?

Barium Enema Study (Option A)

While contrast enema is the diagnostic imaging procedure of choice for suspected distal obstruction and can demonstrate microcolon in cases of distal atresia or meconium plug syndrome 2, 1, imaging should not precede surgical consultation when peritoneal signs are present 1. The contrast enema would be appropriate after surgical evaluation and stabilization, not as the immediate next step.

Rectal Suction Biopsy (Option C)

Rectal suction biopsy is indicated for diagnosing Hirschsprung disease when this is the suspected diagnosis 2. However, this diagnostic procedure should not be performed before surgical evaluation in a neonate with acute peritoneal signs, as the clinical presentation suggests a more urgent surgical emergency requiring immediate intervention 1.

Appropriate Management Sequence

Once surgical consultation is obtained, the following should occur:

• Immediate resuscitation with NPO status, nasogastric tube decompression, and intravenous fluid resuscitation to correct dehydration and electrolyte abnormalities 1
• Blood gas and lactate levels assessment to evaluate for bowel ischemia 1
• Broad-spectrum antibiotics if peritonitis or necrotizing enterocolitis is suspected 1
• Plain abdominal radiographs as the first imaging study to demonstrate dilated bowel loops, air-fluid levels, and presence or absence of distal gas 1
• Contrast enema after stabilization if distal obstruction is confirmed and the patient is stable enough for the procedure 2, 1

Differential Diagnosis Considerations

The clinical presentation is consistent with several surgical emergencies:

• Intestinal atresia (ileal, jejunal, or colonic) - presents with failure to pass meconium, abdominal distention, and bilious vomiting 3, 4
• Midgut volvulus - can present identically and requires urgent surgery to prevent bowel necrosis 1, 5
• Hirschsprung disease - congenital megacolon is a leading cause of abdominal distention in full-term newborns (33.8% of cases) 6
• Meconium plug syndrome or meconium ileus - though these may respond to therapeutic enema, peritoneal signs mandate surgical evaluation first 2

The presence of peritoneal signs (tenderness and absent bowel sounds) elevates the urgency beyond diagnostic considerations and mandates immediate surgical involvement. 1