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.
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.
Probably due to immature mucosal barrier, motility, immunity and abnormal colonisation.
One attempt at a clinical definition is used in Bell's stages of necrotising enterocolitis:
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.
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. Doppler appearances on day 1 may also be predictive of NEC Peds 2006, PMID 17079572.
Thrombocytopenia, neutropenia, coagulopathy, acidosis may be seen, indicating severe disease. A persistently normal CRP on the other hand has a high negative predictive value.
Stop enteral feeds. Treat with broad spectrum antibiotics if mild to moderate symptoms, consider additional anaerobic cover if definite perforation.
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). NEJM Volume 354(21), 25 May 2006, pp 2225-2234. PMID 18580206
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.
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. J Perinatol. 2006 Feb;26(2):93-9. PMID 16319937
Organisms appear to be different too: mostly candida and coagulase negative staphylococcus on peritoneal aspirate culture cf enterobacteraciae for NEC. Pediatrics. 2005 pmid 15995004
The preferred way of dealing with the problem. The Lancet Volume 368, Issue 9543 , 7 October 2006-13 October 2006, Pages 1271-1283. PMID 17027734; Arch 2008 PMID 18006565
No benefit from oral immunoglobulins (though no trial of IgA alone). 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.
ie below dietary requirements, for purpose of avoiding mucosal atrophy, stimulation of gut hormones and motility. Decreases bacterial overgrowth. Continued intraluminal antigenic stimulation maintains the immunological barrier eg Peyers patches, intraepithelial lymphocytes. Fasting causes IgA levels to fall. These effects may also extend beyond the gut.
The higher the proportion of total intake as breast milk, the less the risk of NEC or death after the first 2 weeks of life among extremely low birth weight infants. Argument for quicker establishment of feeds? PMID: 18716628
Cochrane review: just 2 trials, with total of 74 infants! Differing protocols eg 12-24ml/kg/d starting between day 1 and day 8. Control group was typically fasted for 6-18 days, else given water only. Overall, trophic feeding reduced time to full feeds and length of stay. No effect on NEC. But quite a lot of heterogeneity.
In the only trial of trophic vs advancing feeds (ie increasing by 20ml/kg/d as tolerated) – stopped early due to 7 cases of NEC in latter group cf only 1 in former. But only 1/3 received breast milk, and feeds were started on average on day 10, which is not typical of current practice. Caution with interpretation advised, as a 2 tailed p test adjusted for repeated analyses would exceed 0.6! On most other measures, the advancing feeds group did better. Cochrane 2008, PMID 18425878
Cochrane review of slow vs fast advancement of feeds (3 trials, 396 infants - but unblinded, of course...) could not find any NEC benefit, whereas there was a delay in establishing full feeds. Cochrane 2008, PMID 18425870 Neonatal Nutrition and Metabolism (Google books, 2006) says no increased risk. Hard to know whether a true increase in NEC would outweigh the benefits of establishing feeds sooner; or similarly whether the complications of prolonged TPN would eventually outweigh any NEC complications.
Probably best to balance an uncertain risk of NEC against likely problems of prolonged TPN, repeated venepuncture and cannulation, risk of sepsis. Arch Dis Child 2004 89(4):F289-92. PMID 15210657
Breast milk is better than formula; but formula better than nothing? Some debate about bolus vs continuous – irrelevant where such small volumes involved? Start to advance feeds from day 5. Neonatal Nutrition and Metabolism (Google books, 2006)
Right side position leads to better gastric emptying but also more liquid reflux in prems (J ped 2004)
Gastroschisis rates have increased over the past 25 yrs in both developed and developing countries. Associated with young mums, smoking, drugs, GU infections. Note also confounding with Chlamydia (43% of mums of affected cases positive).
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