The acute-phase response in differentiating sepsis from inflammation in neonates who require abdominal surgery

In neonates, the influence of surgery on the inflammatory response has not been fully characterized and it remains difficult to differentiate an inflammatory response from sepsis. In this study, we evaluated changes in interleukin-6 (IL-6) and C-reactive protein (CRP) in neonates undergoing different major abdominal surgeries who had a normal postoperative course without infection.

In total, 43 neonates undergoing major abdominal surgery owing to congenital malformations involving the gastrointestinal tract, and who did not show blood culture positivity were enrolled in the study. As a control group, 40 neonates with proven sepsis were enrolled in the study over the same period. Blood samples for IL-6, CRP, and white blood cell count (WBC) determination were drawn before surgery and 48, 96, and 144 h [postoperative days (POD) 2,4, and 6] after surgery.

There was a statistically significant increase in IL-6 concentrations on POD 2 compared with preoperative levels (p < 0.05). After POD 2, IL-6 levels decreased to preoperative levels. There was a statistically significant increase in CRP concentrations on POD 2, 4, and 6 (p < 0.05). Levels of CRP tended to be higher after surgery, and began to fall by the 6th day, but were still statistically higher than preoperative levels. In the sepsis group, CRP concentrations on day 6 were lower than in the surgery group (p < 0.05). White blood cell counts did not show statistically significant differences preoperatively versus postoperatively.

In contrast to previous studies, our results show high levels of IL-6 on POD 2 and CRP on POD 6. It is important to differentiate between the diagnoses of sepsis and postoperative inflammation, because of the need to treat the infection. High levels of IL-6 and CRP are not always associated with sepsis after major abdominal surgeries, but may instead be associated with the inflammatory response and multiorgan dysfunction. Further studies are needed to better differentiate sepsis from inflammatory responses in patients undergoing other surgeries.