Introduction

The Tokyo Guidelines recommend a CRP cutoff >10 mg/L for diagnosing acute cholangitis. However, this threshold was defined in lithiasic populations and may not be applicable to malignant biliary obstruction, where CRP elevation often reflects tumor-driven inflammation rather than true infection. Applying this universal threshold in oncologic settings risks antibiotic overuse and promotes resistance.

Aims & Methods

This study aimed to reassess the diagnostic value of the current CRP cutoff in tumor-related cholangitis and to identify a more appropriate threshold to enhance specificity and guide targeted antibiotic use.
We conducted a retrospective monocentric study of consecutive patients at a tertiary center between May 2016 and October 2024. Among 571 patients undergoing ERCP, 268 patients with confirmed malignant biliary obstruction and available bile sampling were included. Bacteriological status was defined as positive when either direct bile examination or culture isolated microorganisms. CRP levels, leukocyte counts (hyperleukocytosis >10,000/mm³), and tumor etiology were recorded. ROC curve analysis was performed to determine the optimal CRP cutoff. Comparative analyses employed Mann-Whitney U, chi-square, and multivariate logistic regression.

Results

The mean age was 65.9 ± 12.4 years, with an equal sex distribution (50% male). Tumor etiologies included pancreatic cancer (56%), cholangiocarcinoma (22%) — 40 hilar and 18 distal cases, gallbladder cancer (13%), ampulloma (7%), and extrinsic or secondary compression (3%). The median CRP was significantly higher in culture-positive patients (47 mg/L [IQR 21–98]) compared to culture-sterile patients (22 mg/L [IQR 11–36]; p<0.001). ROC analysis identified an optimal CRP cutoff of 21 mg/L (AUC = 0.64), achieving a sensitivity of 67% and specificity of 54%. Hyperleukocytosis was present in 66% of culture-positive cases versus 31% of sterile cases (p<0.001). In multivariate analysis, CRP ≥21 mg/L (OR 2.1; 95% CI [1.3–3.4]; p=0.002) and hyperleukocytosis (OR 3.4; 95% CI [1.9–5.9]; p<0.001) were independently associated with bile bacteriological positivity.

Conclusion

In malignant biliary obstruction, the universal CRP threshold of 10 mg/L lacks specificity and risks antibiotic overuse. A higher threshold around 21–25 mg/L, combined with leukocyte count assessment, improves diagnostic precision. Our findings advocate for a context-specific adaptation of the Tokyo Guidelines to better differentiate tumor-related inflammation from true infection, ultimately enhancing patient safety and antimicrobial stewardship in oncologic care.