Serum interleukin-6 is not associated with postoperative intra-abdominal adhesion severity in a rat model.

AIM: To assess whether serum interleukin-6 (IL-6) measured on postoperative day 14 reflects adhesion severity and to compare intraperitoneal alteplase, N-acetylcysteine (NAC), and combined treatment. METHODS: In this exploratory randomised study, 40 male Wistar rats were allocated to untreated adhesion, alteplase, NAC, alteplase plus NAC, or sham groups (n = 8 per group). Serum IL-6 and macroscopic adhesion grade were assessed on day 14. Group differences were analysed using the Kruskal-Wallis tests followed by Benjamini-Hochberg-adjusted Dunn comparisons; associations were assessed using Spearman correlation. RESULTS: Serum IL-6 differed among groups (H = 18.08; p = 0.001). Median serum IL-6 concentrations were 14.52 pg/mL (IQR 9.91-19.13) in untreated animals, 30.70 pg/mL (IQR 27.31-34.09) after alteplase (p = 0.003), 24.95 pg/mL (IQR 17.48-32.42) after NAC (p = 0.037), 30.76 pg/mL (IQR 24.16-37.36) after combined treatment (p = 0.007), and 18.36 pg/mL (IQR 11.49-25.23) in sham animals (p = 0.320). Adhesion grades differed (H = 20.80; p < 0.001) and were lower after alteplase and combined treatment (both p = 0.041); the NAC comparison was not significant (p = 0.054). Serum IL-6 was not correlated with adhesion grade (ρ = -0.131; 95% CI -0.425 to 0.189; p = 0.422). CONCLUSION: A single serum IL-6 measurement on day 14 did not reflect adhesion severity. Serial serum measurements and concurrent peritoneal or tissue biomarkers may be more informative.