Definition & Population

The effective treatment of necrotizing enterocolitis relies on accurately diagnosing the disease, and the lack of agreement on a universal definition has contributed to the absence of a definite aetiology and pathogenesis. Bell’s staging, published in 1978, helped to capture NEC under one umbrella, but as our understanding and management of the condition improves modifications have been made to Bell’s criteria. Neonatal clinicians, researchers and epidemiologists are all eager for a more robust definition of NEC as an unambiguous definition is crucial to determine incidence, for clinical research and to investigate management and outcomes.

It is also essential to have large, reliable datasets, and the lack of data on babies who have had NEC, the paucity of population-based data and the scarcity of information on long-term outcomes are significant problems. The absence of ‘clean’ data, which have been assessed for duplicates, inconsistencies and errors, has hindered research, and SIGNEC speakers have pointed to the need for clean databases they can share. This would significantly improve confidence that cases labelled as NEC are in fact NEC. The UKNC-NEC study (below) and The NEC Registry , set up by the National Organisation for Rare Disorders (NORD) in the USA, are important recent steps in the right direction in this regard.

Most of the data and research available on NEC are from the United Kingdom and North America. The first national study of the incidence of severe or fatal necrotizing enterocolitis undertaken anywhere in the United Kingdom was an analysis of babies born in England and admitted to all 163 neonatal units between 1 January 2012 and 31 December 2013. Results from the project, which was undertaken by the UK Neonatal Collaborative Necrotising Enterocolitis (UKNC-NEC) study group, were first made public at the 2014 SIGNEC meeting by Dr Cheryl Battersby. In 2016, she gave a presentation on the UKNC Necrotising Enterocolitis Study: Feeding antecedents and a case-definition.

In the study, severe NEC was confirmed by laparotomy, leading to death, or both and included the following data:

Criteria Number of babies
Admitted to 163 neonatal units 118 073
Born <32 weeks 14 678
Born ≥ 32 weeks 103 395
Total deaths 2 065
Had severe NEC 531 (0.45% of babies admitted)
Born <32 weeks + severe NEC 462 (87%)
Born ≥ 32 weeks + severe NEC 69
Survived to discharge 284 (53%)
Had laparotomy 423
Died after laparotomy 139
Deaths attributed to NEC 247 (12% of deaths)
Born <32 weeks + death attributed to NEC 222 (90%)

In North America, it is estimated that NEC affects babies at a rate of 1-3 per 1000 births1.



1. Trends in care practices, morbidity, and mortality of extremely preterm neonates,  1993–2012.
Stoll, B. J. et al, JAMA 314, 1039–1051 (2015).


Related Research

1. Incidence and enteral feed antecedents of severe neonatal necrotising enterocolitis across neonatal networks in England, 2012-13; a whole population study.

Authors: C. Battersby, N.Longford, S. Mandalia, K. Costeloe, N. Modi

Published online 7 November 2016

2. Development of a Gestational Age-Specific Case Definition for Neonatal Necrotizing Enterocolitis.

Authors: C. Battersby, N.Longford, K. Costeloe, N. Modi

Published online March 2017










Some of the presentations referred to can be viewed using the buttons below. They appear by kind permission of the speakers.



This section is intended for professionals with an interest in necrotizing enterocolitis. It is not intended for the families of babies who are currently receiving care in a neonatal unit or who previously had a baby cared for in a neonatal unit. It contains information and images which they may find distressing. They should visit our For Families section.