Necrotizing enterocolitis

From Ganfyd

(Redirected from Necrotising enterocolitis)
Jump to: navigation, search

A disease of newborns, particularly of the premature, in which gut mucosal integrity is lost, leading to feed intolerance and signs of sepsis. Potentially leads to intestinal perforation, which can be catastrophic. Of uncertain, probably complex, pathology.

Contents

Epidemiology

Associated with prematurity and low birth weight, and the risk increases with increasing prematurity. Enteral feeding is also a pre-condition, although the risk appears lower with breast milk than with formula on meta-analysis. IUGR and absent end diastolic flow are risk factors in some but not all studies; current ADEPT trial is addressing this. Seen rarely in term infants, in whom it is mostly associated with other disease eg respiratory distress syndrome, neonatal asphyxia, polycythaemia. Occasionally occurs in epidemics, although it is not associated with any one specific organism.

Aetiology

Probably due to immature mucosal barrier, motility, immunity and abnormal colonisation.

Clinical Features

LogoKeyPointsBox.pngLuckly although most premature infants will have some abdominal symptoms they do not have:
  • Feeding intolerance
  • Abdominal distention
  • Bloody stools after 8 to 10 days of age
  • Either or both of pneumatosis intestinalis & portal venous gas on X-ray BUT DO NOT DEPEND ON X-ray changes

One attempt at a clinical definition is used in Bell's stages of necrotising enterocolitis:

  1. Suspected disease
    • Mild systemic signs (apnoea, bradycardia, temperature instability)
    • Mild intestinal signs (abdominal distention, gastric stasis, bloody stools)
    • Non-specific or normal radiological signs
  2. Definite disease
    • Mild to moderate systemic signs
    • Additional intestinal signs (absent bowel sounds, abdominal tenderness)
    • Specific radiological signs (pneumatosis intestinalis or portal venous air)
    • Laboratory changes (metabolic acidosis, thrombocytopaenia)
  3. Advanced disease
    • Severe systemic illness (hypotension)
    • Additional intestinal signs (striking abdominal distention, peritonitis)
    • Severe radiological signs (pneumoperitoneum)
    • Additional laboratory changes (metabolic and respiratory acidosis, disseminated intravascular coagulopathy)

In advanced disease, discolouration of the abdominal wall may be seen.

This classification is of limited value, in that "suspected disease" is extremely non-specific. Ideally an earlier stage could be defined objectively before the onset of systemic signs seen in "definite disease".

Investigations

Plain abdominal X-ray shows thickened bowel wall or abnormal pattern early on; serial films useful, especially if there is a persistent abnormal loop. Pneumatosis may show as linear or bubbly patterns, or can look like stool (which is rarely seen radiologically in first 2 weeks of life). Free gas may be more apparent on supine cross-table lateral or left-side down decubitus films.

Doppler shows increased arterial flow in early NEC, and may become a useful test in the future.

Thrombocytopenia, neutropenia, coagulopathy, acidosis may be seen, indicating severe disease. A persistently normal CRP on the other hand has a high negative predictive value.

Treatment

Stop (or rather reduce to minimium using human milk) enteral feeds. Treat with broad spectrum antibiotics if mild to moderate symptoms, consider additional anaerobic cover if definite perforation.

Surgery

The only definite indication for surgical intervention is perforation, but even (isolated) portal gas may not be an indicator of severe disease. If a focal perforation found, then peritoneal drainage alone may be sufficient, else resection usually required.

However, in a RCT of resection vs peritoneal drainage, performed for perforated necrotizing enterocolitis, the type of operation did not influence survival or other clinically important early outcomes in preterm infants, independent of presence of pneumatosis or acidosis (n=117). [1]

Normal baby small bowel is 2-300cm long. After resection, 90% survival seen where there is a minimum of 40cm residual small bowel, but drops rapidly below that. Birmingham does small bowel transplant.

Focal/Spontaneous Intestinal Perforation

Appears to be a different condition - patients are smaller and more premature than in NEC, are more likely to have had a PDA and treated with indomethacin, and can usually be managed conservatively with peritoneal drainage and antibiotics alone. [2]

Organisms appear to be different too: mostly candida and coagulase negative staphylococcus on peritoneal aspirate culture cf enterobacteraciae for NEC. [3]

Prevention or prophylaxis

The preferred way of dealing with the problem.[4] [5]

  • Since enteral feeding is an important risk factor, different protocols exist for the gradual introduction of milk to the gut. Minimal enteral feeding is recognized as being important for maintaining mucosal integrity and reduces the time to establishment of full enteral feeding.
  • Systematic review of probiotics for preventing NEC: 5 RCTs since 2002. 6 different organisms used, different regimens! Overall, significant reduction in NEC and mortality (beyond death due to NEC!). So promising, if confusion over which regimen. [6]
  • Breast milk banking
  • Oral vancomycin reduced incidence by 50% [7] but might give short term benefit only, and risk of encouraging drug resistance if given for prolonged periods.
  • Egg phospholipid formula (more PUFAs) less stage II/III NEC [8].
  • Arginine supplementation appeared to be of benefit in 1 study.

No benefit from oral immunoglobulins, although no trial of IgA alone. [9]. No definite benefit of high vs low UAC position for incidence of NEC (other benefits for high position). Red cell transfusion has been found to be a risk factor, but a trial of high vs low transfusion thresholds did not affect incidence of NEC.


Postnatal CMV can present with NEC like illness without pneumatosis.

References

  1. Rees CM, Eaton S, Kiely EM, Wade AM, McHugh K, Pierro A. Peritoneal drainage or laparotomy for neonatal bowel perforation? A randomized controlled trial. Annals of surgery. 2008 Jul; 248(1):44-51.(Link to article – subscription may be required.)
  2. Attridge JT, Clark R, Walker MW, Gordon PV. New insights into spontaneous intestinal perforation using a national data set: (1) SIP is associated with early indomethacin exposure. Journal of perinatology : official journal of the California Perinatal Association. 2006 Feb; 26(2):93-9.(Link to article – subscription may be required.)
  3. Coates EW, Karlowicz MG, Croitoru DP, Buescher ES. Distinctive distribution of pathogens associated with peritonitis in neonates with focal intestinal perforation compared with necrotizing enterocolitis. Pediatrics. 2005 Aug; 116(2):e241-6.(Link to article – subscription may be required.)
  4. Lin PW, Stoll BJ. Necrotising enterocolitis. Lancet. 2006 Oct 7; 368(9543):1271-83.(Link to article – subscription may be required.)
  5. Chauhan M, Henderson G, McGuire W. Enteral feeding for very low birth weight infants: reducing the risk of necrotising enterocolitis. Archives of disease in childhood. Fetal and neonatal edition. 2008 Mar; 93(2):F162-6.(Link to article – subscription may be required.)
  6. Martin CR, Walker WA. Probiotics: role in pathophysiology and prevention in necrotizing enterocolitis. Seminars in perinatology. 2008 Apr; 32(2):127-37.(Link to article – subscription may be required.)
  7. Siu YK, Ng PC, Fung SC, Lee CH, Wong MY, Fok TF, So KW, Cheung KL, Wong W, Cheng AF. Double blind, randomised, placebo controlled study of oral vancomycin in prevention of necrotising enterocolitis in preterm, very low birthweight infants. Archives of disease in childhood. Fetal and neonatal edition. 1998 Sep; 79(2):F105-9.
  8. Carlson SE, Montalto MB, Ponder DL, Werkman SH, Korones SB. Lower incidence of necrotizing enterocolitis in infants fed a preterm formula with egg phospholipids. Pediatric research. 1998 Oct; 44(4):491-8.
  9. Foster J, Cole M. Oral immunoglobulin for preventing necrotizing enterocolitis in preterm and low birth-weight neonates. Cochrane database of systematic reviews (Online). 2001; (3):CD001816.(Link to article – subscription may be required.)
Personal tools