Necrotizing enterocolitis (NEC) is a leading cause of emergency surgery in neonates, most commonly affecting very low birthweight preterm infants. It involves inflammation and necrosis of the bowels. Risk factors include prematurity, enteral feedings, and circulatory instability. Clinically, infants may experience feeding intolerance and abdominal distension. Diagnosis involves abdominal x-rays showing signs like pneumatosis intestinalis or portal venous gas. Treatment involves stopping feeds, antibiotics, and possible surgery for severe or perforated cases. Long-term complications can include strictures and short bowel syndrome.

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

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. 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

16. 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

17. 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

18. BELL STAGING CRITERIA
STAGE CLINICAL X-RAY TREATMENT
I. Suspect
NEC
Mild abdominal
distention
Poor feeding
Emesis
Mild ileus Medical
Work up for
Sepsis
II. Definite
NEC
The above, plus
Marked abdominal
distention
GI bleeding
Significant
Ileus
Pneumatosis
Intestinalis
PVG
Medical
III. Advanced
NEC
The above, plus
Unstable vital signs
Septic Shock
Pneumo-
Peritoneum
Surgical

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