Necrotizing Enterocolitis

In

Neonates

Done By :

Dr . Mohammed Fawzy

Necrotizing Enterocolitis

• Definition.• Epidemiology• Risk Factors

• Pathophysiology• Clinical Presentation

• Diagnosis• Management

• Prognosis• Prevention

Definition :

 is one of the most common gastrointestinal emergen-cies in the newborn infant. It is a disorder characterized by ischemic necrosis of the intestinal mucosa, which is associated with inflammation, invasion of enteric gas forming organisms, and dissection of gas mural and luminal .

• Although early recognition and aggres-sive treatment of this disorder has im-proved clinical outcomes,

NEC accounts for substantial long-term morbidity in survivors of neonatal inten-sive care, particularly in premature very low birth weight infants (birth weight below 1500 g).

Epidemiology :

• Incidence: 0.3-2.4 / 1000 live births .• 2-5 % of all NICU admissions .• 5-10 % of VLBW infants .• Over 90 % of cases occur in preterm babies• About 10 % occur in term newborns: essen-

tially limited to those that have some under-lying illness or condition requiring NICU ad-mission.

Risk factors

1) Prematurity : MOST IMPORTANT RISK FACTOR

inflamatory propensity of the immature gut. Decreases intestinal barrier function. Decreased gut motility and abberent vascular regulation.

2) Enteral feeding : Aggressive advancement of feeding. Non human milk feeding

3) Intestinal ischemia : Perinatal asphyxia . ## polycythemia . Patent ductus arteriosus & indomethacin . Umbilical catheterization .

Maternal cocaine abuse – 2.5 times increases risk

Pathophysiology

Clinical Presentation

Fulminant presentation

The onset of NEC usually occurs in the 1st 2 weeks of life (with a mean age at onset of 12 days) but can be as late as 3 months of age in VLBW infants

• Abdominal (en-teric) signs:

Distension Tenderness Gastric aspirate, vomiting Ileus Abdominal wall erythema, induration Ascites Abdominal mass Bloody stool

• Systemic signs:

Respiratory distress, apnea, bradycardia

Lethargy, irritability

Temp. instability

Poor feedingHypotensionAcidosisOligureaBleeding

diathesis

Modified Bell´s Staging Criteria for Necrotizing Enterocolitis (NEC)

1 ) Bell's stage 1/Suspected disease:

Mild systemic disease (apnoea, bradycardia, temperature instability) Mild intestinal signs (abdominal distention, gastric residuals, bloody stools) Non-specific or normal radiological signs

2 ) Bell's stage 2/Definite disease:

Mild to moderate systemic signs Additional intestinal signs (absent bowel sounds, abdominal tenderness) Specific radiologic signs (pneumatosis intestinalis ) Laboratory changes (metabolic acidosis, thrombocytopenia)

3 ) Bell's stage 3/Advanced disease: Severe systemic illness (hypotension) Additional intestinal signs (striking abdominal distention, peritonitis) Severe radiologic signs (pneumoperitoneum) Additional laboratory changes (metabolic and respiratory acidosis, DIC )

Diagnosis :

The diagnosis of necrotizing enterocolitis (NEC) is based on the presence of the characteristic clinical features of abdominal disten-tion and rectal bleeding

( grossly bloody stools), and the abdominal radiographic finding of pneumatosis intestinalis. Assessment of infants with suspected NEC includes abdominal

imaging, blood studies, stool analysis, and sepsis evaluation. Although the results of this evaluation often are nonspecific, certain findings are supportive of the diagnosis of NEC, and in the case of abdominal imaging (ie, pneumatosis intestinalis), may be diagnostic.

Laboratory studies :-

No lab test is specific for NEC The most common triad : Thrombocytopenia Persistent metabolic acidosis Severe refractory hyponatremia ↑WBC, ↓WBC . Hyperkalemia Stool: reducing substances, occult blood

HAT

H •Hyponatremia

A •Metabolic Acidosis

T •Thrombocytopenia

Radiologic studies

Abdominal X-ray: A-P & Lateral view – should be done every 8 hours in the first 2 days

• The following characteristic radiographic features are seen in the majority of infants with suspected NEC . :

1) An abnormal gas pattern with dilated loops of bowel that is consistent with ileus, and is typically seen in the early stages of NEC.

2) Pneumatosis intestinalis : the hallmark of NEC, appears as bubbles of gas in the small bowel wall, and is seen in most patients with stages II and III NEC .

3) Pneumoperitoneum :typically appears when bowel perforation occurs in pa-tients with III NEC. A substantial amount of intraperitoneal air may result in the "football" sign on a supine radiograph. This sign consists of a large hypolucent area in the central abdomen with markings from the falciform ligament.

4) Sentinel loops, a loop of bowel that remains in fixed position, is suggestive of necrotic bowel and/or perforation in the absence of pneumatosis intesti-nalis.

N .B /

Portal venous gas (PVG) had been thought to be a predictor of poor outcome and an indication for surgical intervention. However, subsequent data do NOT support these assumptions .

!!!!!!!!!

Pneumatosis intestinalis

Multiple dilated loops of small bowel

Extensive pneumatosis intestinalis.

Close up demonstrates intraluminal gas (yellow * ) with prominent intramural gas (blue arrows). 

Ultrasound :

• bowel wall thickening free fluid • alteration of vascular state• intramural gas manifesting as high echo foci within the

bowel wall .• Sensitive for pneumatosis intestinalis .

Contrast enema :

Contrast enemas are NOT recommended if NEC is suspected, as it may

result in bowel perforation with extravasation of contrast material into

the peritoneum .

Sepsis evaluation :  A sepsis evaluation is performed when NEC is sus-pected because of sepsis is a common concomitant finding . Culture results may be used in guiding antibiotic therapy.

A diagnostic abdominal paracentesis :

occasionally is performed to obtain fluid for culture and Gram stain in infant with severe ascites or when peritonitis is suspected because of progressive clinical deterioration and an unchanging radiographic bowel gas pattern. In

these cases, the identification of enteric organisms in the peritoneal fluid

supports the diagnosis of peritonitis from intestinal perforation and helps

guide appropriate antibiotic coverage .

Management

A ) Medical :• Rapid initiation of therapy is required for suspected as well as proven NEC cases.

• There is no definitive treatment for established NEC and, therapy is directed at

supportive care and preventing further injury with

-Cessation of feeding,

-Nasogastric decompression, and

-Administration of intravenous fluids.

• Once blood has been drawn for culture, systemic antibiotics (with broad coverage for gram-positive, gram-negative, and anaerobic organisms) should be started immedi-ately.

B ) Indications for surgery :

1 ) Absolute indications:• Evidence of perforation on abdominal roentgenograms (pneumoperitoneum) or • Positive abdominal paracentesis (stool or organism on Gram stain from peritoneal fluid).

2 ) Relative indications:• Failure of medical management, • Single fixed bowel loop on roentgenograms, • Abdominal wall erythema, or • A palpable mass.

PROGNOSIS.:

• Medical management fails in about 20–40% of patients with pneumatosis intestinalis at diagnosis; of these, 10–30% die.

• Early postoperative complications : Wound infection, dehiscence, and stomal problems (prolapse, necrosis).

• Later complications : Intestinal strictures develop at the site of the necrotizing lesion in about 10% of surgically or medically managed

patients.

• After massive intestinal resection, -Complications from postoperative NEC include short-

bowel syndrome (malabsorption, growth failure, malnutrition), • Premature infants with NEC who require surgical intervention

or who have concomitant bacteremia are at increased risk for adverse growth

and neurodevelopmental outcome.

• The overall mortality is 9% to 28% regardless of surgical or medical

intervention.

PREVENTION: Always better than cure!

• Newborns exclusively breast-fed have a reduced risk of NEC.

• Early initiation of aggressive feeding may increase the risk of NEC in VLBW infants.

• Gut stimulation protocol of minimal enteral feeds followed by judicious volume advancement may decrease the risk.

• Probiotic preparations have also decreased the incidence of NEC. . Induction of GI maturation.

• Incidence of NEC is significantly reduced after prenatal steroid therapy.

• Alteration of the immunologic status of the intestine using immunoglobulin A (IgA) and im-munoglobulin G (IgG) supplementation

SUMMARY AND RECOMMENDATIONS

• Necrotizing enterocolitis (NEC) is one of the most common gastrointestinal emergencies in

the newborn infant . It occurs in 1 to 3 per 1000 live births. The incidence decreases with increasing

gestational age and birth weight (BW), and is about 6 to 7 percent in very low birth weight infants (BW less than 1500 g). Term infants who develop NEC usually have a preexisting illness, such as congenital heart disease or sepsis.

• NEC primarily occurs in healthy, growing, and feeding premature infants. It presents with both

nonspecific systemic signs (eg, apnea, respiratory failure, poor feeding, lethargy, or temperature instability) and abdominal signs (eg, distension, gastric retention, tenderness, vomiting, rectal bleeding, and diarrhea).

• The Bell staging criteria defines the different stages of NEC based upon the severity of clinical findings

.

• The diagnosis of NEC is based upon the presence of the characteristic clinical features of abdominal

distention and rectal bleeding (hematochezia), and the abdominal radiographic finding of pneumatosis

intestinalis. At times, radiographic findings may be equivocal and treatment decision should be based upon clinical suspicion and findings.

• Results of laboratory evaluation, including blood studies and stool analysis, are nonspecific, but may be supportive of the diagnosis of NEC. In particular, low platelet count, metabolic acidosis, and

• a heme-positive stool are associated with NEC.

THANK YOU

Dr . Mohammed Fawzy