NECROTIZING ENTEROCOLITIS

1. NECROTIZING ENTEROCOLITIS Janice Nicklay Catalan M.D.

2. OBJECTIVES • Ability to diagnose and treat the signs and symptoms of NEC • Ability to evaluate radiographs for the classic findings of NEC • List several long-term complications associated with NEC

3. NECROTIZING ENTEROCOLITIS • Epidemiology: • most commonly occurring gastrointestinal emergency in preterm infants • leading cause of emergency surgery in neonates • overall incidence: 1-5% in most NICU’s • most common in VLBW preterm infants • 10% of all cases occur in term infants

4. NECROTIZING ENTEROCOLITIS • Epidemiology: • 10x more likely to occur in infants who have been fed • males = females • blacks > whites • mortality rate: 25-30% • 50% of survivors experience long-term sequelae

5. NECROTIZING ENTEROCOLITIS • Pathology: • most commonly involved areas: terminal ileum and proximal colon • GROSS: • bowel appears irregularly dilated with hemorrhagic or ischemic areas of frank necrosis • focal or diffuse • MICROSCOPIC: • mucosal edema, hemorrhage and ulceration

6. NECROTIZING ENTEROCOLITIS • MICROSCOPIC: • minimal inflammation during the acute phase • increases during revascularization • granulation tissue and fibrosis develop • stricture formation • microthrombi in mesenteric arterioles and venules

7. NECROTIZING ENTEROCOLITIS • Pathophysiology: UNKNOWN CAUSE…….

8. CIRCULATORY INSTABILITY Hypoxic-ischemic event Polycythemia PRIMARY INFECTIOUS AGENTS Bacteria, Bacterial toxin, Virus, Fungus MUCOSAL INJURY INFLAMMATORY MEDIATORS Inflammatory cells (macrophage) Platelet activating factor (PAF) Tumor necrosis factor (TNF) Leukotriene C4, Interleukin 1; 6 ENTERAL FEEDINGS Hypertonic formula or medication Malabsorption, gaseous distention H2 gas production, Endotoxin production

9. RISK FACTORS • Prematurity: • primary risk factor • 90% of cases are premature infants • immature gastrointestinal system • mucosal barrier • poor motility • immature immune response • impaired circulatory dynamics

10. RISK FACTORS • Infectious Agents: • usually occurs in clustered epidemics • normal intestinal flora • E. coli • Klebsiella spp. • Pseudomonas spp. • Clostridium difficile • Staph. Epi • Viruses

11. RISK FACTORS • Inflammatory Mediators: • involved in the development of intestinal injury and systemic side effects • neutropenia, thrombocytopenia, acidosis, hypotension • primary factors • Tumor necrosis factor (TNF) • Platelet activating factor (PAF) • LTC4 • Interleukin 1& 6

12. RISK FACTORS • Circulatory Instability: • Hypoxic-ischemic injury • poor blood flow to the mesenteric vessels • local rebound hyperemia with re-perfusion • production of O2 radicals • Polycythemia • increased viscosity causing decreased blood flow • exchange transfusion

13. RISK FACTORS • Enteral Feedings: • > 90% of infants with NEC have been fed • provides a source for H2 production • hyperosmolar formula/medications • aggressive feedings • too much volume • rate of increase • >20cc/kg/day

14. RISK FACTORS • Enteral Feedings: • immature mucosal function • malabsorption • breast milk may have a protective effect • IGA • macrophages, lymphocytes • complement components • lysozyme, lactoferrin • acetylhydrolase

15. Gestational age: < 30 wks 31-33 wks > 34 wks Full term Age at diagnosis: 20 days 11 days 5.5 days 3 days CLINICAL PRESENTATION • Time of onset is inversely related to gestational age/birthweight

16. Gastrointestinal: Feeding intolerance Abdominal distention Abdominal tenderness Emesis Occult/gross blood in stool Abdominal mass Erythema of abdominal wall Systemic Lethargy Apnea/respiratory distress Temperature instability Hypotension Acidosis Glucose instability DIC Positive blood cultures CLINICAL PRESENTATION

17. Sudden Onset: Full term or preterm infants Acute catastrophic deterioration Respiratory decompensation Shock/acidosis Marked abdominal distension Positive blood culture Insidious Onset: Usually preterm Evolves during 1-2 days Feeding intolerance Change in stool pattern Intermittent abdominal distention Occult blood in stools CLINICAL PRESENTATION

18. BELL STAGING CRITERIA

19. RADIOLOGICAL FINDINGS • Pneumatosis Intestinalis • hydrogen gas within the bowel wall • product of bacterial metabolism • a. linear streaking pattern • more diagnostic • b. bubbly pattern • appears like retained meconium • less specific

20. RADIOLOGICAL FINDINGS • Portal Venous Gas • extension of pneumatosis intestinalis into the portal venous circulation • linear branching lucencies overlying the liver and extending to the periphery • associated with severe disease and high mortality

21. RADIOLOGICAL FINDINGS • Pneumoperitoneum • free air in the peritoneal cavity secondary to perforation • falciform ligament may be outlined • “football” sign • surgical emergency

22. LABORATORY FINDINGS • CBC • neutropenia/elevated WBC • thrombocytopenia • Acidosis • metabolic • Hyperkalemia • increased secondary to release from necrotic tissue

23. LABORATORY FINDINGS • DIC • Positive cultures • blood • CSF • urine • stool

24. TREATMENT • Stop enteral feeds • re-start or increase IVF • Nasogastric decompression • low intermittent suction • Antibiotics • Amp/Gent; Vanc/Cefotaxime • Clindamycin • suspected or proven perforation

25. TREATMENT • Surgical Consult • suspected or proven NEC • indications for surgery: • portal venous gas; pneumoperitoneum • clinical deterioration • despite medical management • positive paracentesis • fixed intestinal loop on serial x-rays • erythema of abdominal wall

26. TREATMENT • Labs: q6-8hrs • CBC, electrolytes, DIC panel, blood gases • X-rays: q6-8hrs • AP, left lateral decubitus or cross-table lateral • Supportive Therapy • fluids, blood products, pressors, mechanical ventilation

27. PROGNOSIS • Depends on the severity of the illness • Associated with late complications • strictures • short-gut syndrome • malabsorption • fistulas • abscess * MOST COMMON