Hyperbilirubinemia as an Indicator of Complicated Appendicitis

Reliable preoperative identification of complicated appendicitis may support appropriate selection for operative or non-operative pathways. This study evaluated admission total serum bilirubin as an adjunctive marker of complicated disease and compared its performance with white blood cell count (WBC).

We prospectively enrolled 150 patients who underwent appendicectomy for suspected acute appendicitis at Cairo University Hospital over six months. Operative findings classified cases as negative appendicectomy, uncomplicated appendicitis, or complicated appendicitis. Diagnostic accuracy was assessed among patients with operative appendicitis. Receiver operating characteristic (ROC) analysis was used to select thresholds based on the maximum Youden index. Exact Clopper-Pearson 95% confidence intervals (CIs) were calculated for sensitivity, specificity, positive predictive value (PPV), and negative predictive value (NPV).

Of 150 participants, 35 (23.3%) had a macroscopically normal appendix, 86 (57.3%) had uncomplicated appendicitis, and 29 (19.3%) had complicated appendicitis. For complicated versus uncomplicated appendicitis, total bilirubin had an area under the ROC curve (AUC) of 0.904 (bootstrap 95% CI 0.827-0.968; P < 0.001). At a threshold of ≥0.95 mg/dL, sensitivity was 82.76% (95% CI 64.23%-94.15%), specificity 94.19% (86.95%-98.09%), PPV 82.76% (64.23%-94.15%), and NPV 94.19% (86.95%-98.09%). WBC had an AUC of 0.717 (95% CI 0.596-0.826; P < 0.001); at ≥14.3 x 10⁹/L, sensitivity was 72.41% and specificity 76.74%.

Admission total serum bilirubin showed good discrimination for complicated appendicitis in this single-center operative cohort and performed better than WBC alone. It should be interpreted as an adjunct to clinical assessment and imaging, and the identified threshold requires independent validation.