NECROTIZING ENTEROCOLITIS

Dr. Devendra Nargawe

• Necrotizing enterocolitis is the most common serious surgical emergency in NICU.

• NEC occurs in 2- 5 % of all NICU admission and 5-10% of VLBW infants.

ETIOLOGY • It is probably multifactorial . There are several

associated factors including: • Prematurity• Rapid advances in feeding of ELBW infants.• Asphyxia• PDA• Umbilical artery cath. Tip at or above the mesenteric

artery.• Indomethacin / ibuprofen• Aminophylline • Polycythemia• Hypothermia

PATHOGENESIS

Perinatal hypoxia

Umbilical vessel catheterization

Vasospasm thrombo- embolic

phenomena

Bacterial invasion

Toxins(neuraminidase)

Hypovolemia(shock)

Preterm baby

Diving reflex(mesenteric vasospasm)

Reduced intestinal perfusion

Ischemic mucosal injury Direct mucosal damage

Low cardiac output

HypothermiaBlood lossSepticemiaExchange

transfusion

Type and amount of feeds

Hyperosmolar feeds

Intestinal stasis

CLINICAL FINDINGS• Feeding residuals ( coffee ground aspirates)

• Abdominal distension

• Constipation

• Blood in the stool

• Erythema of abdominal wall ( when peritonitis is present)

• Lethargy or other non-specific signs of infection

* Data from PGIMER shows that the peak age for NEC in preterm infants is from end of the 1st week of life to the 2nd week

STAGING

• A staging devised by Bell and letter modified by Walsh AND Kleighman is useful for therapeutic decisions .

Stage Systemic sign

Intestinal signs

Radiological signs

Rx

Ia suspected NEC

Temp. instability, apnea, bradycardia, lethargy

Elevated pre lavage residual, mild abdominal distension , emesis , guaiac positive stool

Normal or intestinal dilatation, mild ileus

NBM, antibiotics for 3 days

Ib suspected NEC

--do-- Bright red blood from rectum

Do Do

Stage Systemic sign

Intestinal signs

Radiological signs

Rx

II a definite NEC , mildly ill

Temperature instability, apnea, bradycardia, lethargy

Absent bowel sounds , abdominal tenderness

Intestinal dilatation, ileus, pneumatosis intestinalis( small gas bubble in bowel loops)

NBM , antibiotics for 7-10 days

II b definite NEC moderately ill

Do plus mild metabolic acidosis

Do plus definite abdominal tenderness +/- abdominal cellulitis or right lower quadrant mass

Same as II a plus portal vein gas +/-ascites

NBM, antibiotic for 14 days , NaHCO3 for acidosis

Plain abdominal x-ray on the left showed pneumatosis intestinalis (large arrow), a specific characteristic finding in necrotizing enterocolitis (NEC). X ray on the right is a follow-up film which showed free air indicating the perforation of the bowel (small arrow)

Stage Systemic sign

Intestinal signs

Radiological signs

Rx

III a advanced NEC severely ill , bowel intact

Same as II b plus hypotension, bradycardia, apnea, combined respiratory and metabolic acidosis, DIC, neutropenia

Same as above plus signs of generalized peritonitis, marked tenderness and distension of abdomen

Same as IIB plus definite ascites

Same plus more fluid abd. ParacentesisInotropic agents, ventilation

III b advanced NEC severely ill , bowel perforated

Same as III a Same as III a Same as II b plus pneumoperitonium

Same + abdominal surgery

LABORATORY FINDINGS

• Thrombocytopenia

• Hyponatremia

• Metabolic acidosis

• Evidence of DIC

• overt or occult blood in the stool

• Urine should be examined for hyphae and budding yeast to rule out systemic candidiasis.

• Blood and stool culture are mandatory

DIFFERENTIAL DIAGNOSIS

• infectious enterocolitis – diarrhea with blood in stool

• Candidemia –may mimic early features of NEC

• Sepsis and pneumonia may cause ileus without NEC.

• Gut immaturity

• Congenital intestinal obstruction

• Spontaneous intestinal obstruction

• Intussusception

• Dysentery

• Campylobacter diarrhea

APPROACH TO CASE OF SUSPECTED NEC

Suspected NEC

NBM, continuous gastric aspiration, antibiotics, complete work up for sepsis, platelet count, stool for occult blood, ABG,

electrolytes, AXR, remove umbilical cath.

Stage 3 disease

Yes

Pediatric Sx opinion and abdominal paracentesis

Perforation

Flank discharge

No improvement in next 48h

Laparotomy

No

Continue supportive care in all stages

MANAGEMENT

• General considerations• Avoid or minimize factors which may contribute to

bowel ischemia.• Maintain a high level of suspicion , when advancing

feedings in very low birth weights baby.

MEDICAL MANAGEMENT

• Stop enteral feeds and oral medications• Duration of NBM

• Stage 1 : 3 days• Stage 2 : 7-10 days• Stage 2b & 3 : 14 days

Keep the GIT decompressed using 8 -10 F NGT. Replace the aspirate with N/2 saline with KCL every 8 hours.

• IV fluids• Give normal maintenance for stage I and II• In stage III , more than 200ml/kg/day may be required

due to 3rd space losses.

OTHER MEASURES

• Maintain adequate tissue perfusion using symapathomimetic agents. (dopamine 5-8 microgram/kg/min)

• Give plasma or blood transfusion as required

• Inj. Vit. K if bleeding or if not given in last 1 week

• Correct metabolic acidosis

• Start antibiotics as per culture report• Duration of therapy

• Stage I : 3 days (depending on culture)• Stage II : 7 to 10 days• Stage III : 14 days

MONITORING

• Aggressive monitoring forms a corner stone for successful outcome

1. Clinical • Abdominal girth • Gastric aspirate – quantity and nature 1-2 hourly• CRT, BP, RR, HR, and PaO2

2. Radiological • Initially 8 hourly x-ray abdomen during the first 48 to 72 hours,

thereafter once daily.3. Laboratory

• Hematocrit and blood glucose 8 hourly• Serum Na+/ K+ : 12 hourly• Platelet count and neutrophil count once initially and then 48

hrs. later • ABG 12 hourly during the initial 48 to 72 hours

SURGICAL MANAGEMENT

• Indications• GI perforation• Full thickness necrosis• Peritonitis

• Features which suggestive perforation/ full thickness necrosis are:• Pneumoperitonium• Positive abdominal paracentesis • Portal venous gas on plain x-ray• Abdominal wall erythema / induration • Fixed loop on serial radiographs

• Supportive evidence:• Abdominal tenderness• Thrombocytopenia ( <1,00,000/ cu. Mm)• Clinical deterioration• Severe GI hemorrhage

COMPLICATIONS

• Short term• Irreversible shock• Extensive bowel infraction• secondary infection ( usually with enteric organism or

staph. )

• Long term• Intestinal stricture and bowel obstruction• Short bowel syndrome ( after bowel resection)

PROGNOSIS

• It depends upon• Severity of illness• Amount of bowel removed• Associated complications

PREVENTION

• Delay enteral feeding in stressed preterm infants who have suffered hypoxic ischemic episodes.

• Avoid rapid increases in the volume of feeds

• Treat polycythemia aggressively.

• Do not feed preterm with PDA

• Stop feeds with bilious aspirate or continuous large gastric aspirates

• Do not feed during dopamine infusion

• Prophylactic probiotics reduce severe NEC by 66%. 1 sachet 12 hourly for 21 days for all neonates weighing <1250 gm at birth .

REFERENCE

• Care Of Newborn – Meherban Singh

• PGI NICU HANDBOOK OF PROTOCOLS; 4th edition 2010

• Handbook of Neonatology ; Dr Hemant Jain

• Manual of newborn care ; 7th edi. John p. cloherty