NECROTIZING ENTEROCOLITIS Janice Nicklay Catalan M.D.

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

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

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

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

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

NECROTIZING ENTEROCOLITIS Pathophysiology: UNKNOWN CAUSE…….

MUCOSAL INJURY 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

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

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

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

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

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

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

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

CLINICAL PRESENTATION 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 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

BELL STAGING CRITERIA

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

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

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

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

LABORATORY FINDINGS DIC Positive cultures blood CSF urine stool

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

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

TREATMENT Labs: q6-8hrs X-rays: q6-8hrs Supportive Therapy 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

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