Bilirubin; a diagnostic marker for appendicitis

Every investigation that can contribute towards a diagnosis of appendicitis is valuable to the emergency general surgeon. Previous research has suggested that hyperbilirubinaemia is a more specific marker for both simple and perforated appendicitis than WBC (white blood count) and CRP (C-reactive protein), but this investigation is not commonly used to help diagnose appendicitis.

This study investigated whether there is an association between hyperbilirubinaemia and appendicitis. We also reviewed the diagnostic value of bilirubin in perforated vs simple appendicitis, and compared it with the serum C-reactive protein (CRP) and white blood cell count (WBC).

This single centre, prospective observational study included all patients admitted with right iliac fossa (RIF) pain who had liver function tests performed. Statistical analysis was performed using Fisher's exact test to compare bilirubin, WBC and CRP levels for normal appendices, simple appendicitis, and perforated appendicitis.

242 patients were included in this study, of whom 143 were managed operatively for RIF pain. Hyperbilirubinaemia was significantly associated with appendicitis vs RIF pain of other aetiologies (p < 0.0001). Bilirubin had a higher specificity (0.96), than WBC (0.71) and CRP (0.62), but a lower sensitivity (0.27 vs 0.68 and 0.82 respectively). Hyperbilirubinaemia was associated with perforated appendicitis vs simple appendicitis with statistical significance (p < 0.0001). Bilirubin had a higher specificity (0.82) than both WBC (0.34) and CRP (0.21), but a lower sensitivity (0.70 vs 0.80 and 0.95 respectively).

Our findings confirm that hyperbilirubinaemia has a high specificity for distinguishing acute appendicitis, especially when perforated, from other causes of RIF pain, particularly those not requiring surgery.