GI

Necrotizing Enterocolitis

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Necrotizing Enterocolitis, NEC, Neonatal Necrotizing Enterocolitis, Pneumatosis Intestinalis

  • Definition
  1. Acute, ischemic intestinal necrosis in Premature Infants with mucosa invasion by gas-forming Bacteria
  • Epidemiology
  1. Most common serious surgical condition in NICU patients
  2. Leading gastrointestinal cause of death in newborns
  3. Age of onset
    1. Mean age: 12 days of life
    2. Frequently occurs at approximately 3 days of life
  • Risk Factors
  1. Prematurity (mean Gestational age 30 to 32 weeks)
    1. Represent more than 90% of NEC cases
  2. Other risks
    1. Antibiotic exposure
    2. Congenital Heart Disease
    3. Indomethacin
  3. Protective factors
    1. Maternal Antibody (after 28 weeks gestation)
  • Pathophysiology
  1. Acute, ischemic intestinal necrosis in Premature Infants
    1. Uncontrolled, exaggerated response to intestinal colonization in the premature newborn
    2. Gas-forming enteric Bacteria invade bowel mucosa
    3. Virus Gastroenteritis (e.g. Rotavirus) can also occur
  2. Pseudomonas aeruginosa
    1. Implicated in some cases of NEC (especially in Premature Infants and those with Neutropenia)
  3. Toll-like receptors (TLRs)
    1. Bacterial receptors that appear to be involved in the pathogenesis of Necrotizing Enterocolitis
    2. Research is focused on the TLRs in the prevention and treatment of NEC
  • Signs
  1. Course
    1. Either severe and rapidly progressive or insidious
  2. General
    1. Respiratory distress or apnea
    2. Bradycardia
    3. Lethargy
    4. Hypotension or decreased peripheral perfusion
  3. Gastrointestinal symptoms
    1. Abdominal Distention
    2. Abdominal tenderness to palpation
    3. Increased gastric aspirates
    4. Bilious Emesis or Hematemesis
    5. Decreased or absent bowel sounds
    6. Localized abdominal mass
    7. Ascites
    8. Bloody stools
  • Differential Diagnosis
  1. Neonatal Pneumonia
  2. Neontal Sepsis
  3. Spontaneous intestinal perforation
  4. Infectious enterocolitis (e.g. Rotavirus)
  5. Severe Inborn Errors of Metabolism
  6. Feeding Intolerance
  • Labs
  1. Complete Blood Count with Platelet Count
    1. Thrombocytopenia
  2. Basic chemistry panel (e.g. chem8)
    1. Metabolic
    2. Hyponatremia
  • Staging
  • Bell Criteria
  1. Stage 1: Suspected NEC
    1. Increased distention or gastric Residual Volumes
    2. Non specific systemic signs
    3. Normal abdominal XRay or ileus
  2. Stage 2: Confirmed NEC
    1. Bloody stool
    2. Abdominal Xray with Pneumatosis Intestinalis or portal venous gas
  3. Stage 3: Advanced NEC
    1. Critically ill infant (Sepsis, peritonitis)
    2. Peritoneal free air (bowel perforation) may be present
  • Imaging
  1. Abdominal Xray (Anteroposterior or Cross Table lateral)
    1. Multiple dilated bowel loops that remain consistently placed on serial imaging
    2. Pneumatosis Intestinalis
      1. Gas in bowel wall in linear or with small bubbles (seen in more than 50% of NEC patients)
    3. Surveillance with serial films every 6 hours is performed in high risk Premature Infants
  2. Abdominal Ultrasound
    1. Thick walled loops of bowel
    2. Decreased bowel motility
  • Management
  1. Antibiotics
    1. Piperacillin-Tazobactam (Zosyn) 50 mg/kg IV every 6 hours
      1. Zosyn replaces Ampicillin and Gentamicin due to increasing resistance
    2. Add Vancomycin IV if culture positive for Staphylococcus epidermidis
  2. Emergent surgery indications
    1. Bowel infarction with progressive disease
    2. Bowel perforation
  3. Supportive care
    1. Gastrointestinal rest (NPO)
    2. Gastric decompression with Nasogastric Tube
    3. Intravenous Fluid and Electrolyte replacement
    4. Blood Pressure support
    5. Parenteral nutrition
  • Prevention
  1. Probiotics
    1. Probiotics significantly reduce risk of severe Necrotizing Enterocolitis and mortality in those at risk
    2. Alfaleh (2014) Cochrane Database Syst Rev (4):CD005496 +PMID:21412889 [PubMed]
    3. Olsen (2016) Neonatology 109(2):105-12 +PMID:26624488 [PubMed]
  • Prognosis
  1. High morbidity and mortality that has changed little in 30 years
  2. Surgical survival approaches 50% (80% for infants <1 kg)
  • References
  1. McAlmon in Cloherty (1991) Manual of Neonatal Care, Little Brown, Boston, p. 511-7
  2. (2016) Sanford Guide to Antimicrobial Therapy, accessed IOS app 5/6/2016
  3. Afrazi (2011) Pediatr Res 69:183-8 [PubMed]