Association of gastric residual volumes with necrotising enterocolitis in extremely preterm infants—a case–control study

Necrotising enterocolitis (NEC) is a potentially serious illness with significant mortality and morbidity in preterm infants. Previous studies have reported association of volume and colour (bile and blood stained) of gastric residuals (GR) with NEC. We aimed to study this association in our cohort of extremely preterm (EP) infants. In a case–control study using retrospective data (January 2006–December 2011), EP (gestation < 28 weeks) infants with confirmed NEC ≥ stage II (cases) were compared with infants without NEC (controls) matched for birth weight (BW) and gestational age (GA). Forty cases of NEC ≥ stage II diagnosed at a median (IQR) age of 16.5 days (10.3–23) were compared with 40 controls matched for gestation (± 3 days) and birth weight (± 680 g). Median maximum GR volume (GRV) from birth to the day of occurrence of NEC was significantly higher in cases vs. controls (5.9 vs.3.7 ml; p < 0.001). Increased maximum GRV was associated with NEC ≥ Stage II in adjusted analysis (aOR 1.36, 95%CI 1.06–1.75, p = 0.017). There was no significant difference in GRV between cases and controls throughout the clinical course, including 72, 48 and 24 h before the onset of NEC. However, green (65.0% vs. 27.5%, p = 0.001) and haemorrhagic GRs (45.0% vs. 27.5%, p = 0.092) were higher 24 h before the diagnosis of NEC. Conclusion: GRV was not associated with NEC ≥ stage II. However, green and haemorrhagic GRs were significantly higher 24 h before the diagnosis of the illness. Adequately powered prospective studies are needed to confirm the significance of our findings.