Septicaemia - risk factors for evolution of Necrotising Enterocolitis

(NEC) in extremely preterm infants

Background and aims: NEC is one of the most unpredictable diseases in premature infants

and one of the leading causes of morbidity and mortality in neonatal intensive care units (NICU).The pathophysiology of NEC is considered to be multi-factorial.

We investigated the incidence of NEC in relation to the septicaemia in preterm infants during an nine year period in the NICU.

Material and methods: Retrospective study of 161 infants born before 28 weeks of gestational age (GA) and hospitalized in the NICU in Lund between 2002-2010.Criteria for septicaemia were positive blood cultures or U-Arabinitol quota>5.Septicaemia onset was registered as early (<72hours of life) or late (>72hours of life).The diagnosis of NEC was based on clinical or radiographic criteria or findings in surgery or at post-mortem examination. The clinical and radiographic features of the condition are defined byBell staging criteria. Stage II is defined when at least one clinical finding (bilious gastric aspirate or vomiting, abdominal distension, occult or gross blood in the stool) occurs together with a  radiographic finding (pneumatosis intestinalis or hepatobiliary gas) and stage III when at least one of four mentioned clinical finding occurs with radiographic finding ofpneumoperitoneum.

 Results: Out of 161 infants 37,9% (95%CI 30,8-45,6%) were identified as infants with septicaemia and 8,1% (95%CI 4,8-13,3%) with NEC. The median of GA and of birth weight (BW) was 25weeks+0 and 735g respectively.

Out of 61 infants with septicaemia 55,7% (95%CI 43,3-67,5%) was identified coagulase negative staphylococcus (CoNS).

Out of the 13 infants with  NEC 46,2%(95%CI 23,2-70,9) was identified coagulase negative staphylococcus (CoNS).

Out of 61 infants with septicaemia 16,4% (95%CI 9,2-27,6%) developed NEC and out of 100 infants without septicaemia 3%(95%CI 1,0-8,5%) developed NEC .In relation to the early and late septicaemia were incidence of NEC 14,3%(95%CI 4,0-39,9%) and 17%(95%CI 8,9-30,1%) respectively.

Out of 13 infants with NEC 46,2%(95%CI 23,2-70,9%) underwent surgery, 38,5%(95%CI 17,7-64,5%) developed perforated NEC and mortality for NEC was 23,1% (95%CI 8,2-50,3%).

Conclusion: The incidence of NEC in this patient group was 8,1%.Septicaemia was significant risk for evolution of NEC ( p=0.004).The most frequently identified bacteria was coagulase negative staphylococcus.

Congenital and neonatal infections