In a term neonate delivered by lower‑segment cesarean section with meconium‑stained amniotic fluid who was initially stable but now has feeding intolerance and vomiting after each feed, what are the differential diagnoses and what diagnostic and management steps should be taken?

Differential Diagnoses and Management for Neonate with Meconium-Stained Liquor and Feeding Intolerance

This neonate requires urgent evaluation for intestinal obstruction, with bilious vomiting being the most critical red flag necessitating immediate imaging to rule out malrotation with volvulus. 1

Differential Diagnoses

High-Priority Surgical Emergencies

• Malrotation with volvulus: Bilious vomiting in a neonate is malrotation with volvulus until proven otherwise 1
• Intestinal atresia/stenosis: Small bowel or colonic obstruction presenting with feeding intolerance 1
• Meconium ileus: Distal intestinal obstruction from inspissated meconium 2
• Hirschsprung disease: Functional obstruction from absent ganglion cells 2

Medical Causes

• Meconium aspiration syndrome (MAS): Present in approximately 5% of neonates with meconium-stained amniotic fluid, can cause systemic inflammation affecting gut motility 3, 4
• Sepsis/necrotizing enterocolitis: Intraamniotic infection/inflammation is associated with meconium-stained fluid and increases risk of neonatal sepsis 4
• Gastroesophageal reflux: Most common cause of non-bilious vomiting in early weeks, but less likely with complete feeding intolerance 1
• Formula intolerance: Consider if pattern suggests intolerance rather than obstruction 1

Neurologic Causes

• Spinal dysraphism/tethered cord: Can impair bowel peristalsis and cause delayed passage of stool 2

Diagnostic Approach

Immediate Assessment (Within Minutes)

• Determine vomitus character: Bilious (green) versus non-bilious is the single most critical distinction 1
• Assess abdominal examination: Look for distension, tenderness, visible loops, absent bowel sounds 1
• Check for passage of meconium: Delayed passage beyond 24-48 hours suggests obstruction 2
• Vital signs and hydration status: Assess for signs of dehydration or sepsis 1

Physical Examination Specifics

• Abdominal palpation: Feel for pyloric olive (typically 2-8 weeks, less likely in immediate newborn period), masses, or distension 5
• Lower back inspection: Examine for dimples, hair tufts, or skin discoloration suggesting spinal dysraphism 2
• Anorectal examination: Confirm patent anus and assess rectal tone 2

Imaging Studies (Urgent)

If bilious vomiting present:

• Plain abdominal radiograph (supine and cross-table lateral): First-line imaging to assess bowel gas pattern, dilated loops, air-fluid levels, or absence of distal gas 2
• Upper GI contrast study: Gold standard for malrotation—must be performed emergently if bilious vomiting present 1

If non-bilious vomiting with distension:

• Plain abdominal radiograph: Assess for obstruction pattern 2
• Contrast enema: Differentiates structural causes (atresia, Hirschsprung) from functional causes (meconium plug); microcolon suggests proximal obstruction or Hirschsprung 2

Laboratory Studies

• Complete blood count with differential: Assess for sepsis 4
• Blood culture: Given association of meconium-stained fluid with intraamniotic infection 4
• Electrolytes: Assess for dehydration and metabolic derangements from vomiting 1
• C-reactive protein: Evaluate for inflammation/infection 4

Management Algorithm

Immediate Stabilization

1. NPO (nothing by mouth): Stop all feeds immediately 1
2. IV access and fluid resuscitation: Administer maintenance fluids plus replacement of losses 1
3. Nasogastric tube placement: Decompress stomach, monitor output character and volume 1
4. Monitor vital signs continuously: Watch for deterioration suggesting volvulus or sepsis 1

Urgent Surgical Consultation

Obtain immediate surgical consultation if:

• Bilious vomiting present (malrotation with volvulus is time-sensitive emergency) 1
• Abdominal distension with tenderness 1
• Abnormal radiograph showing obstruction pattern 2

Antibiotic Consideration

• Start empiric antibiotics: Given the association between meconium-stained amniotic fluid and intraamniotic infection/inflammation, consider ampicillin and gentamicin pending cultures 4

Respiratory Monitoring

• Assess for MAS: Although initially stable, 5% of neonates with meconium-stained fluid develop MAS, which can present with delayed respiratory distress 3, 4
• Monitor oxygen saturation: Use pulse oximetry to detect evolving respiratory compromise 6

Critical Pitfalls to Avoid

Do Not Delay Imaging for Bilious Vomiting

Any bilious vomiting requires immediate upper GI series to exclude malrotation with volvulus—delays can result in bowel necrosis and death 1. This is a surgical emergency, not a "wait and see" situation.

Do Not Assume Simple Reflux

While gastroesophageal reflux is common, complete feeding intolerance with vomiting after each feed in a neonate warrants obstruction workup first 1. Reflux typically allows some feeds to be tolerated.

Do Not Overlook Sepsis

The association between meconium-stained amniotic fluid and intraamniotic infection means these neonates have higher risk of sepsis and should be evaluated accordingly 4.

Do Not Miss Spinal Dysraphism

Failure to examine the lower back for cutaneous markers can miss neurologic causes of bowel dysfunction 2.

Disposition

• Bilious vomiting or abnormal imaging: Immediate surgical intervention 1
• Non-bilious vomiting with normal initial imaging: Close observation with serial examinations, continued NPO status, and consideration of contrast enema to evaluate for Hirschsprung or meconium plug 2
• All cases: Admit for observation, IV fluids, and serial assessments until diagnosis established and feeding tolerance demonstrated 1