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