Chapter 134: Digestive System Disorders

Differential diagnosis of emesis, jaundice, abdominal distention · Feeding intolerance · Surgical vs medical causes · Sepsis · Inborn errors of metabolism
🩺 Key concept: Bilious vomiting in a term newborn = surgical emergency (malrotation with volvulus) until proven otherwise.

🩺 Neonatal Digestive Disorders: Core Concepts

🤢 Emesis (vomiting)
Bilious = obstruction (volvulus, duodenal atresia) until proven. Non-bilious: GER, pyloric stenosis, overfeeding, IEM, sepsis.
🟡 Jaundice
Direct hyperbilirubinemia (>2 mg/dL or 20% of total) → cholestasis (biliary atresia, GALD, hepatitis, sepsis, TPN).
💨 Abdominal distention
NEC, obstruction, meconium plug, ileus, sepsis, ascites, hypokalemia, hyponatremia.
🍼 Feeding intolerance
Prematurity (immature motility), NEC, sepsis, metabolic (galactosemia), anatomic (atresia, Hirschsprung).
⚕️ Diagnostic approach
Anemia, thrombocytopenia, acidosis, hypoglycemia suggest systemic illness. X-ray, US, contrast studies for obstruction.
📋 Table 134.1 Differential
Emesis: volvulus, pyloric stenosis, Hirschsprung, IEM, CAH, ↑ICP. Abdominal distention: NEC, sepsis, hypokalemia, ascites.
⚠️ Life-threatening causes: Midgut volvulus (bilious emesis), NEC (pneumatosis, perforation), adrenal insufficiency, inborn errors of metabolism (hyperammonemia).

🔍 Approach to common GI symptoms in the newborn

1
Bilious emesis – Assume surgical emergency (malrotation/volvulus) until upper GI series rules out obstruction. Also consider duodenal atresia, jejunal atresia, meconium ileus.
2
Non-bilious vomiting – GER (common), overfeeding, pyloric stenosis (projectile, 3-6 wk), sepsis, IEM (hyperammonemia, acidosis), adrenal insufficiency, ↑ICP.
3
Abdominal distention – X-ray: obstruction (air-fluid levels), NEC (pneumatosis, portal air), meconium plug. Lab: CBC, CRP, electrolytes (hypokalemia, hyponatremia).
4
Feeding intolerance + lethargy – Sepsis, NEC, metabolic (galactosemia, urea cycle defect). Check blood glucose, ammonia, lactate, urine reducing substances.
5
Jaundice + direct hyperbilirubinemia – Evaluate for biliary atresia (acholic stools), GALD (neonatal hemochromatosis), hepatitis, TPN cholestasis, sepsis.

📋 Stepwise management of neonatal digestive emergencies

1
Bilious emesis / suspected volvulus – Immediate NPO, nasogastric decompression, IV fluids, broad-spectrum antibiotics. Urgent upper GI series (or surgery consult if unstable).
2
Suspected NEC – NPO, NG suction, IV antibiotics (ampicillin + gentamicin + metronidazole), serial abdominal X-rays, surgical consult. Support blood pressure, correct acidosis.
3
Hyperammonemia (IEM) – Stop protein intake, IV dextrose, consider dialysis (hemodialysis or peritoneal). Treat with sodium benzoate/phenylacetate (if urea cycle defect).
4
Pyloric stenosis (projectile vomiting, 3-6 wk) – Ultrasound (muscle thickness >3 mm, length >15 mm). Correct electrolytes (hypochloremic metabolic alkalosis). Surgical pyloromyotomy.
5
Direct hyperbilirubinemia / biliary atresia – Urgent evaluation: ultrasound (absent gallbladder, triangular cord sign), liver biopsy, hepatobiliary scintigraphy (HIDA). Kasai procedure before 60 days.
📌 Key lab clues: Hypoglycemia + metabolic acidosis → IEM. Hypochloremia + alkalosis → pyloric stenosis. Direct hyperbilirubinemia + acholic stools → biliary atresia.

🧠 Rapid reflex prompts – Digestive disorders

📌 Bilious emesis in newborn = ?
Surgical emergency (malrotation with volvulus) until proven otherwise.
📌 First test for suspected volvulus?
Upper GI series (contrast study).
📌 Pneumatosis intestinalis on X-ray?
Pathognomonic for necrotizing enterocolitis (NEC).
📌 Cause of vomiting + metabolic alkalosis + hypochloremia?
Pyloric stenosis (projectile vomiting).
📌 Direct hyperbilirubinemia with acholic stools?
Biliary atresia (Kasai procedure before 60 days).
📌 Feeding intolerance + hepatomegaly + cataracts?
Galactosemia (urine reducing substances, GALT enzyme).