Necrotizing enterocolitis


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  • Clinical decision algorithm
  • Necrotizing enterocolitis

    1. 1. Dr Afnan Shamraiz
    2. 2. Introduction:  Necrotizing Enterocolitis: an acquired neonatal acute intestinal necrosis of unknown etiology . NEC is the most common life-threatening emergency of the gastrointestinal tract in the newborn.  Various degrees of mucosal or transmural necrosis of the intestine occurs.  The incidence of NEC is 1–5% of infants in NICU.  Although rare, the disease does occur in term infants (10%)  Birth weight incidence,fatality Gestational age
    3. 3. 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: essentially limited to those that have some underlying illness or condition requiring NICU admission  Sex, race, geography, climate has no role in determining the incidence of NEC
    4. 4. Risk factors influencing NEC prediposition .  Enteral feeding:  Aggressive advancement of feeding.  Non human milk feeding  Abnormal bacterial colonization  Prolonged emperical antibiotic therapy  Decreased commensal flora  Increased pathogenic bacteria Maternal cocaine abuse – 2.5 times increases risk Prematurity is the single greatest risk factor
    5. 5. Prematurity Deficient mucosal barrier (suppressed GI hormones and mucosal enzymes)  Dysfunctional intestinal host defense system  Decreased motility  Dysregulation of intestinal microcirculation (increased bacterial overgrowth)  6
    6. 6. Intestinal Ischemia      Term infants (polycythemia, asphyxia, exchange transfusion, congenital heart disease, IUGR) PDA Indocin Cocaine exposure in utero Gastroschisis 7
    7. 7. Risk Factors: in Term Babies Limited to those that have some underlying illness or condition requiring NICU admission.  Congenital Heart Disease  Intrauterine growth restriction  Polycythemia  Hypoxic-ischemic events  The mean gestational age of infants with NEC is 30 to 32 weeks,
    8. 8.  PATHOLOGY AND PATHOGENESIS: Distal part of the ileum Involved most frequently Proximal segment of colon  In fatal cases, gangrene may extend from the stomach to the rectum.  NEC probably results from an interaction between loss of mucosal integrity due to factors like ischemia, infection, inflammation, and the host's response to that injury like circulatory, immunologic, inflammatory responses resulting in necrosis of the affected area.
    9. 9.  PATHOLOGY AND PATHOGENESIS: contd..  Various bacterial and viral agents, including  , have been recovered from cultures.  However, is identified.   NEC rarely occurs before the initiation of enteral feeding and is much less common in infants fed human milk. Coagulation necrosis is the characteristic histologic finding of intestinal specimens.
    10. 10. PRIMARY INFECTIOUS AGENTS Bacteria, Bacterial toxin, Virus, Fungus CIRCULATORY INSTABILITY Hypoxic-ischemic event Polycythemia MUCOSAL INJURY INFLAMMATORY MEDIATORS Inflammatory cells (macrophage) Platelet activating factor (PAF) Tumor necrosis factor (TNF) Leukotriene C4, Interleukin 1; 6 ENTERAL FEEDINGS Malabsorption, gaseous distention H2 gas production, Endotoxin production
    11. 11. Enteral feeding Ischemic or toxic mucosal damage Bacterial proliferation Loss of mucosal integrity nvasion of mucosa and submucosa Intramural gas TransmuralnecrosisI Perforation Peritonitis
    12. 12. Microbiologic Flora and Infection Several organisms have been accused, but non has been proven to be causative:  Enterobacteriaceae  Enterobactersakazakii  Coagulase-negative staphylococci: SIP  Closrtidium perfringens  Candida species: SIP  Cytomegalovirus  Torovirus  HIV  Mucormycosis
    13. 13. Mean Age at Presentation Gestational age (weeks) Age at onset (days) < 30 20 31-33 14 34 5 Full term 2 14
    14. 14. Clinical Presentation  Course of the disease  Fulminant presentation  Slow, paroxysmal 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
    15. 15. Clinical Presentation  Abdominal (enteric) 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 feeding Hypotension Acidosis Oligurea Bleeding diathesis
    16. 16. Stage I (suspected disease): mild systemic signs (apnoea, bradycardia, temperature instability),  mild GIT signs (abdominal distension, large gastric aspirates, bloody stools),  non-specific or normal radiological signs) 
    17. 17. Stage II (definite disease): mild systemic signs  with additional GI signs (absent bowel sounds, abdominal tenderness),  specific radiological signs (dilated loops of intestines, pneumatosis intestinalis or portal venous air),  abnormal laboratory investigations (e.g. metabolic acidosis, thrombocytopenia) 
    18. 18. Stage III (advanced disease): severe systemic illness (with haemodynamic instability), .  additional GI signs (gross abdominal distension, peritonitis),  severe radiological signs (pneumoperitoneum),  additional laboratory findings (e.g. metabolic and respiratory acidosis, disseminated intravascular coagulopathy 
    19. 19. Staging NEC – Bell’s Classification Stage Clinical findings Radiographic findings I: Suspected NEC Ia Temp instability, apnea, lethargy, increased residuals, abd distention. Ib Normal or mild ileus. See above. + grossly bloody stool. II: Proven NEC IIa IIb See above. + absent bowel sounds. +abd Intestinal dilation, ileus, tenderness. Appear mildly ill. ascites, pneumatosis intestinalis. See above. Appear moderately ill. +metabolic acidosis. +thrombocytopenia. III: Advanced NEC IIIa See II. Bowel intact. Hypotension, bradycardia, apnea. +peritoneal signs. DIC, neutropenia. IIIb See III. + Bowel perforation. Portal venous gas. Pneumoperitoneum (football sign) – specific for stage IIIb.
    20. 20.  MODIFIED BELL’S STAGING OF NEC: Based on: 1. Systemic Signs 2. Intestinal Signs 3. Radiological Signs Classified into: I. Suspected: II. Definite : A (Mildly ill) , B (Moderately ill) III. Advanced: A (Severely ill,bowel intact), B (Severely ill,bowel perforated)
    21. 21. Initial work up: what to look for No lab test is specific for NEC   CBC ↑WBC, ↓WBC, ↓PMN  Thrombocytopenia  Neutropenia (<1500/microL) –poor prognosis  DIC panel (PT/INR, PTT, Fibrinogen, D-dimer)  Elevated PT/INR, PTT, D-dimer  Decreased Fibrinogen  METABOLIC (may have values similar to those found in sepsis)  Hyponatremia (<130)  Hyperglycemia  Hyperkalemia  Blood gas  Metabolic acidosis   Blood culture Fecal occult blood test Serial measurements of CRP – diagnostic and prognostic
    22. 22. Blood studies: Thrombocytopenia COMMON TRIAD OF SIGNS Persistent Hyponatremia Severe Refractory Metabolic Acidosis
    23. 23. Radiology studies  Abdominal X-ray: ○ Abnormal gas pattern, ileus ○ Bowel wall edema ○ Pneumatosis intestinalis ○ Fixed position loop ○ Intra hepatic-portal venous gas ( in the absence of UVC) ○ Pneumoperitonium - left lateral decubitus or cross-table lateral views
    24. 24. 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
    25. 25. Pneumatosis Intestinalis
    26. 26. Supine AXR, The bowel is mildly dilated with gas, mainly on the left side. The bubbly pattern of gas seen mainly in the right lower quadrant represents intramural gas.
    27. 27. Fixed Loop Sign The finding of a single loop or several loops of dilated(enlarged) small intestine that remain unchanged in position for 24 to 36 hours is referred to as the persistent “rigid” loop sign and suggests lack of movement of the intestine due to death of a segment of intestine
    28. 28. 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
    29. 29. Portal Air Dilated stomach & loops of bowel
    30. 30. RADIOLOGICAL FINDINGS  Pneumoperitoneum  free air in the peritoneal cavity secondary to perforation ○ falciform ligament may be outlined  “football” sign  surgical emergency
    31. 31. Example of football sign:
    32. 32.   Intestinal perforation. Abdominal Xray in NEC demonstrates marked distention and massive pneumoperitoneum Free air below the anterior abdominal wall. Example of cross-table lateral x-ray with free air
    33. 33. NEC with perforation
    34. 34. Rigler sign Rigler's sign, also known as the double wall sign, is seen on an x-ray of the abdomen when air is present on both sides of the intestine, i.e. when there is air on both the luminal and peritoneal side of the bowel wall.
    35. 35.  Abdominal ultrasound:  Thick-walled loops of bowel with hypomotility.  Intraperitoneal fluid is often present.  Intramural gas can be identified in early-stage NEC  In the presence of pneumatosis intestinalis, gas is identified in the portal venous circulation within the liver.  Color Doppler US is more accurate than abdominal radiography in depicting bowel necrosis in NEC.  Gas bubbles in hepatic parenchyma  Pseudo-kidney sign- central echogenic focus and hypoechoic rim
    36. 36. Sonogram of a bowel loop shows differentiation of inter luminal gas from intramural gas. The intraluminal gas (L) is surrounded by a thickened bowel wall. Within the bowel wall are multiple hyperechoicfoci (arrows), which represent intramural gas
    37. 37. Sonogram shows a bowel loop with a large amount of intramural gas (arrows) in the more dependent and vertically oriented parts of the loop. This gives the bowel wall a typical granular appearance and causes a posterior artifact.
    38. 38. Pneumatosis Necrosis
    39. 39. Histopathology Normal small bowel NEC: Hemorrhagic necrosis beginning at the mucosa and working its way down into the wall
    40. 40. Histopathology Pneumatosis in the submucosa of the small bowel
    41. 41.  Differential diagnosis of NEC :  Specific infections (systemic or intestinal)- Pneumonia, Sepsis.  Gastrointestinal obstruction, volvulus, malrotation,  Isolated intestinal perforation.  Severe Inherited Metabolic disorders. (e.g., galactosemia with Escherichia coli sepsis)  Feeding intolerance  Idiopathic focal intestinal perforation can occur spontaneously or after the early use of postnatal steroids and indomethacin.
    42. 42.  TREATMENT:  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, gramnegative, and anaerobic organisms) should be started immediately.
    43. 43. Algorithm for the treatment of necrotizing enterocolitis
    44. 44.  TREATMENT: Contd.. Umbilical catheters if present should be removed.  Ventilation should be assisted as required.  Intravascular volume replacement with crystalloid or blood products.  Cardiovascular support with volume and/or inotropes.  Correction of hematologic, metabolic, and electrolyte abnormalities.  Careful attention to respiratory status, coagulation profile, and acid-base and electrolyte balance are important. 
    45. 45.  MONITORING:  Sequential abdominal grith measuremet  Sequential anteroposterior and cross-table lateral or lateral decubitus abdominal x-rays to detect intestinal perforation;  Serial determination of hematologic status,  Serial determination of electrolyte status, and  Serial determination of acid-base status.
    46. 46.  Indications for surgery : Absolute indications:  Evidence of perforation on abdominal roentgenograms (pneumoperitoneum) or  Positive abdominal paracentesis (stool or organism on Gram stain from peritoneal fluid).  Relative indications:  Failure of medical management,  Single fixed bowel loop on roentgenograms,  Abdominal wall erythema, or  A palpable mass. 
    47. 47.  Ideally, surgery should be performed after intestinal necrosis develops, but before perforation and peritonitis occurs.  Peritoneal drainage may be helpful for patients with peritonitis who are too unstable to undergo surgery. Peritoneal drainage is more successful in patients with isolated intestinal perforation.
    48. 48. Initial signs of possible NEC (bell’s stage I ) •NPO •GI decompression- low constant sucton, replace output with electrolytes •CBC with differentials, blood culture, CRP, S.Electrolytes •Abdominal radiograph •Begin antibiotics Mild to Moderate (Bell’s stage II) Advanced (Bell’s Stage III) •Serial abdominal radiographs •Serial abdominal radiographs •Broad spectrum antibiotics for 7- 10 days •Broad spectrum antibiotics for 7- 10 days •NPO for 5-10 days, parentaral nutrition •NPO for 10-14 days, parentaral nutrition •Monitor electrolytes •Monitor electrolytes •Serial CBCs every 12h to 24h for 2-3 days •Serial CBCs every 12h to 24h for 2-3 days •Co-mangement with paediatric surgeon •Hemodynamic support •Monitor coagulation abnormalities and correct Indications for surgery •Intestinal perforation •Fixed adynamic loop – necrotic gut •Signs suggestive of necrotic gut –persistent severe thrombocytopenia, severe metabolic acidosis
    49. 49.  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.
    50. 50.  complications….  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.
    51. 51.  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 immunoglobulin G (IgG) supplementation.