Surgery for intestinal injuries in very preterm infants: a Norwegian population-based study with a new approach to disease classification

Objective To evaluate population-based data on very preterm infants (<32 weeks gestation) operated for intestinal injuries, focusing on necrotising enterocolitis (NEC) and focal intestinal perforation (FIP). Design Nationwide, population-based registry cohort study. Setting All 21 neonatal units in Norway. Participants All very preterm infants born from 2014 through 2021 and admitted to a neonatal unit. Main outcome measures Incidence of surgery for subgroups of intestinal injuries, medical record data on laboratory-radiology results, anatomical location of affected bowel, length of resections, number of re-operations, morbidities of prematurity and/or death before discharge. Results Abdominal surgery was performed in 124/4009 (3.1%) very preterm infants and in 97/1300 (7.5%) extremely preterm infants <28 weeks. The main intestinal injuries operated were NEC (85/124; 69%), FIP (26/124; 21%) and 'other abdominal pathologies' (13/124; 10%). NEC cases were divided in (i) acute NEC, extensive disease (n=18), (ii) non-extensive disease (n=53) and (iii) NEC with surgery >3 days after disease onset (n=14). High lactate values immediately prior to surgery was predominantly seen in acute NEC-extensive disease and associated with high mortality. Other laboratory values could not discriminate between acute NEC and FIP. Timing of surgery for acute NEC and FIP overlapped. Radiological absence of portal venous gas was typical in FIP. Most infants (62.5%) underwent a stoma formation at initial surgery. The overall survival rate was 67% for NEC and 77% for FIP. Conclusion NEC cases have different presentation and prognosis depending on the extent of bowel affected. Revised classifications for intestinal injuries in preterm infants may improve prognostication and better guide therapy.