Augmenting the decision making process in acute appendicitis: A retrospective cohort study

Abstract

Introduction: Acute appendicitis is a common surgical diagnosis. We investigated the use of blood markers (WCC, CRP and serum bilirubin) and diagnostic imaging (USS and CT scan) to arrive at this diagnosis, as well as the surgical approach used for appendicectomy.

Methods: This was a retrospective analysis of consecutive patients undergoing appendicectomy in seven hospitals within GG&C Health Board during a 6 month study period. Data were collected from electronic patient records. Sensitivity and specificity of each investigation for diagnosing acute appendicitis was calculated.

Results: 363 patients were included. Appendicectomy was performed open in 53%, laparoscopically in 43% and converted in 4%. Diagnostic imaging was used in 38%. The overall negative appendicectomy rate was 15% (18% when no imaging was used, 23% when USS was used and 1% when CT scanning was used). Elevated bilirubin had a sensitivity of 0.44 and a specificity of 0.84 for detecting acute appendicitis. Sensitivity and specificity for elevated WCC were 0.78 and 0.55, and for elevated CRP were 0.81 and 0.59, respectively. The specificity of bilirubin for diagnosing perforated appendicitis was 0.63.

Discussion: WCC and CRP were sensitive blood markers in acute appendicitis, whereas serum bilirubin was more specific. Diagnostic imaging with a CT scan was very effective at reducing the rate of negative appendicectomy, but USS was not.

Conclusion: Serum bilirubin has utility in diagnosing acute appendicitis, irrespective of whether perforation has occurred. CT scanning should be considered the first line imaging modality for investigation of acute appendicitis if diagnosis is in doubt.

Keywords: Appendectomy; Appendicectomy; Appendicitis; Bilirubin; CRP; CT scan; Diagnosis; Hyperbilirubinaemia; Laparoscopic; Ultrasound scan; White cell count.