✅ Model Answer:
• Figure 1 (supine): Pneumatosis intestinalis – bubbly/linear lucencies within bowel wall (gas in submucosa/subserosa). Portal venous gas – branching radiolucencies from porta hepatis into liver periphery.
• Figure 2 (cross-table lateral): Pneumoperitoneum – large collection of free air under anterior abdominal wall.
• Diagnosis: Necrotizing Enterocolitis (NEC) with perforation (Bell stage III).

✅ Model Answer:
• Stage I (Suspected): Systemic signs (temp instability, apnea, lethargy), GI signs (abdominal distension, gastric residuals), nonspecific X-ray changes (ileus, mild dilation).
• Stage II (Definite – medical NEC): Above signs + pneumatosis intestinalis and/or portal venous gas. Metabolic acidosis, thrombocytopenia.
• Stage III (Advanced – surgical NEC): Severe systemic illness (shock, DIC, respiratory failure) + pneumoperitoneum OR severe pneumatosis with clinical deterioration despite medical therapy.

✅ Model Answer:
• Prematurity (single most important risk factor).
• Enteral feeding (formula vs human milk protective).
• Intestinal dysbiosis.
• Hypoxia-ischemia (PDA, perinatal asphyxia, hypotension).
• Prolonged antibiotics, packed RBC transfusion, H2 blockers/PPIs, maternal chorioamnionitis.

✅ Model Answer:
• Triple hit hypothesis: (1) Intestinal epithelial injury (ischemia, inflammation), (2) enteral feeding (substrate for bacteria), (3) bacterial dysbiosis/overgrowth.
• Premature gut has immature barrier, reduced mucus, altered immune response (TLR4 overactivity).
• Bacterial translocation triggers inflammatory cascade → PAF, TNF, ILs → pneumatosis, necrosis, perforation.
• Pro-inflammatory mediators cause SIRS and shock.

✅ Model Answer:
1. NPO (nil per oral) – stop all enteral feeds.
2. Nasogastric decompression – OG/NG tube to low intermittent suction.
3. Broad-spectrum IV antibiotics – ampicillin + gentamicin + metronidazole.
4. IV fluids and electrolytes – correct dehydration, hypoglycemia, metabolic acidosis.
5. Cardiorespiratory support – oxygen, ventilation if apneic, vasopressors.
6. Serial abdominal X-rays – every 6-12 hours.
7. Serial labs – CBC, platelets, CRP, blood gas, coagulation profile.
8. Pediatric surgery consultation – early involvement.

✅ Model Answer:
• Pneumoperitoneum (free air on X-ray) – absolute indication.
• Progressive clinical deterioration despite maximal medical therapy – worsening acidosis, hypotension, respiratory failure.
• Portal venous gas plus clinical deterioration (relative indication).
• Abdominal wall erythema and induration – evidence of necrotizing fasciitis/perforation.
• Persistent fixed bowel loop on serial X-rays – suggests segmental necrosis.

✅ Model Answer:
• Primary peritoneal drainage (PPD): Bedside procedure under local anesthesia. Indicated for ELBW (<1000 g), critically unstable infant, diffuse peritonitis. Temporizing; some require subsequent laparotomy.
• Exploratory laparotomy with resection: Definitive surgery. Resect necrotic bowel, create ostomy if extensive, or primary anastomosis (selected cases).
• Randomized trials: No significant difference in mortality or neurodevelopmental outcomes between PPD and laparotomy as initial approach. Choice depends on surgeon's assessment and infant stability.

✅ Model Answer:
• Early: Wound infection/dehiscence, intra-abdominal abscess, stoma complications (prolapse, necrosis, stenosis, high output), systemic sepsis, recurrent NEC.
• Late: Intestinal stricture (25-35% of surgically/medically managed NEC), short bowel syndrome (SBS), intestinal failure-associated liver disease (IFALD), adhesive small bowel obstruction.

✅ Model Answer:
• Presentation: Feeding intolerance, vomiting, abdominal distension, delayed stool passage after NEC recovery (4-6 weeks post-NEC).
• Diagnosis: Contrast enema (water-soluble) showing narrowing, typically in left colon or distal ileum.
• Management: If asymptomatic – observe (some resolve spontaneously). Symptomatic strictures require surgical resection (end-to-end anastomosis). Balloon dilation rarely effective.

✅ Model Answer:
• Parenteral nutrition (PN): Central line for long-term PN. Monitor for cholestasis, line sepsis, metabolic bone disease.
• Intestinal adaptation: Early enteral feeds (trophic, then slow advancement) with hydrolyzed formula/breast milk. Teduglutide (GLP-2 analogue).
• Prevent bacterial overgrowth: Cyclical antibiotics (metronidazole, gentamicin).
• Surgical options: Serial transverse enteroplasty (STEP), intestinal lengthening, or intestinal transplant for refractory failure.

✅ Model Answer:
• Increased risk: NEC survivors (especially surgical NEC) have significantly higher rates of neurodevelopmental impairment (NDI) compared to preterm infants without NEC.
• Types: Cognitive delay (IQ <70), cerebral palsy, hearing loss, visual impairment.
• Mechanism: Systemic inflammation, hemodynamic instability, prolonged hospitalization, associated prematurity.
• Follow-up: Neurodevelopmental follow-up (corrected age assessments), early intervention services, hearing/vision screening.

✅ Model Answer:
• Human milk feeding (mother's own milk > donor milk) – reduces NEC risk by 50-80%.
• Probiotics (Lactobacillus, Bifidobacterium) – meta-analyses show reduction in NEC and mortality.
• Standardized feeding protocol (slow advancement, avoid aggressive feeding).
• Avoid H2 blockers/PPIs and prolonged empirical antibiotics (first week of life).
• Delay cord clamping – improves hemodynamic stability.