Role of C-Reactive Protein, White Blood Cell Counts, Bilirubin Levels, and Imaging in the Diagnosis of Acute Appendicitis as a Cause of Right Iliac Fossa Pain

Background Right iliac fossa (RIF) pain is one of the most common modalities of presentation to surgical emergency. It remains a challenge to the treating clinicians to accurately diagnose or to rule out appendicitis. Objective The aim of the study was to compare the efficacy of clinical impression, biochemical markers, and imaging in the diagnosis of RIF pain with special reference to appendicitis and their implication in reducing the negative appendicectomy rates. Methods All patients presenting to casualty with RIF pain were included in the study. Blood investigations including C-reactive protein (CRP), serum bilirubin, white blood cell counts (WBC), and ultrasound (USG) were done. Based on the clinical impression, patients were either posted for appendicectomy or observed in equivocal cases. Patients who had recurrent pain on follow-up underwent appendicectomy or underwent contrast-enhanced computed tomography (CECT) in equivocal cases. Patients who only had a single self-limiting episode with no other alternative diagnosis or had a normal CECT report were included in a non-specific RIF pain group. Results The negative appendicectomy rate was 8.2%. The mean value of WBC counts (9.57x109/L vs 7.88x109/L; p<0.05) and that of serum bilirubin (1.37 mg/dl vs 0.89mg/dl; p<0.05) in the appendicitis and non-appendicitis group, respectively, were statistically significant. The percentage of CRP positivity was higher in the appendicitis group (51.9% vs 15%; p<0.05). The sensitivity, specificity, positive predictive value (PPV), and negative predictive value (NPV) for USG (84.2%, 77.17%, 85.4%, and 75.5%), for CRP (51.8%, 85%, 82%, and 57%), for WBC count (45.1%, 88%, 86.6%, and 48.3%), and for serum bilirubin (69.2%, 75%, 81.4%, and 60.5%) were statistically significant between the groups. Conclusion Imaging and biochemical investigations including bilirubin can act as useful adjuncts to the clinical diagnosis of appendicitis.