Gastric residuals and their relationship to necrotizing enterocolitis in very low birth weight infants

Objective. To determine the characteristics of gastric residuals in very low birth weight (VLBW; less than or equal to1500 g birth weight) infants with and without necrotizing enterocolitis (NEC). Methods. Case-control study compared 51 VLBW infants who had proven NEC ( pneumatosis intestinalis, portal venous gas, and/or perforation; excluding spontaneous gastrointestinal perforations) with 102 control subjects (without suspected or proven NEC) who were matched for birth weight, gestational age, race, and sex and were born January 1996 to December 2001. The age in days at diagnosis of NEC was identified in infants with NEC, and feeding characteristics were recorded for the previous 6 days. Feeding characteristics were recorded for control subjects for the corresponding time period. Results. The median birth weight was 822 g and median gestational age was 26 weeks in both groups. Feeds were started on the fifth day, with a planned increase to full feeds over 10 days ( median) in both groups. Median time to full feeds was 13 days in both groups. Median age of onset of NEC was day 24. The total residuals as a percentage of total feed volume ( the primary outcome), maximum residual in the previous 6 days, maximum residual as a percentage of the feed, maximum residuals over the 6 days, and the percentage of feeds with residuals were higher in the NEC group. The maximum residual (median [25th-75th centiles]) was as follows: control subjects: 2 mL per feed (0.5-3.5) or 14% of a feed (4-33); NEC group: 4.5 mL per feed (1.5-9.8) or 40% of a feed (24-61). The total residuals as percentage of feeds and the average of maximum residuals increased in the NEC group from the first 3 days to the 3 days before diagnosis of NEC, but a similar increase was not noted for control subjects. Conclusions. VLBW infants who developed NEC had more gastric residuals. However, there was overlap with the normal control subjects. Of the gastric residual data, the maximum residual seems to be the best predictor for NEC in the subsequent days.