Serum bilirubin as a predictor of complicated appendicitis: a diagnostic accuracy study

OBJECTIVES: Early identification of complicated acute appendicitis remains a clinical challenge. Serum bilirubin has been proposed as a potential biomarker reflecting disease severity rather than primary diagnosis. To evaluate the diagnostic accuracy of serum bilirubin in predicting complicated acute appendicitis using histopathology as the reference standard. METHODS: A cross-sectional diagnostic accuracy study was conducted among 150 adult patients undergoing appendectomy for suspected acute appendicitis at a tertiary care center. Preoperative serum bilirubin levels were recorded. Histopathological examination served as the gold standard. Diagnostic performance indices, including sensitivity, specificity, predictive values, accuracy, and receiver operating characteristic (ROC) analysis, were calculated. RESULTS: Acute appendicitis was confirmed by histopathology in 82.7 % of cases, of which 11.3 % were complicated. Elevated serum bilirubin (≥1.2 mg/dL) was observed in 71.4 % of complicated appendicitis cases compared to 26.4 % of non-complicated cases (p=0.001). For predicting complicated appendicitis, serum bilirubin demonstrated a sensitivity of 71.4 %, specificity of 73.6 %, and a high negative predictive value of 95.3 %. ROC analysis yielded an AUC of 0.712, indicating fair diagnostic accuracy, with an optimal cut-off of 1.15 mg/dL. CONCLUSIONS: Serum bilirubin is a valuable adjunctive biomarker for predicting complicated appendicitis and effectively ruling out severe disease when levels are normal. Its integration into preoperative assessment may aid risk stratification and clinical decision-making.