Patient characteristics of infants with uncomplicated and complicated NEC.

Data are expressed as median (range) or as numbers unless otherwise specified. Abbreviations: NEC—necrotizing enterocolitis; NIRS—near-infrared spectroscopy; PDA—patent ductus arteriosus; PNA—postnatal age; RBC—red blood cell. Circulatory failure was defined as hemodynamic instability and scored by the need for volume expansion or the use of inotropes or both, from 1 hour before NEC onset until the first forty-eight hours after NEC onset or until surgery took place, whichever came first. Differences between the two groups are marked by * (