Congruence of histological diagnosis with imaging and operation diagnosis in acute appendicitis.

Introduction: The diagnostic process of acute appendicitis is based on clinical symptoms, evaluation of laboratory biomarkers of inflammation and imaging examinations results. Accurate preoperative diagnosis is a key factor in reducing the number of so-called negative appendectomies. The aim of our study was to evaluate the importance of ultrasound in the diagnostic algorithm of acute appendicitis. We also compared the accuracy of the intraoperative diagnosis evaluated by the surgeon with the histopathological findings.

Methods: We performed a retrospective analysis of patients operated for acute appendicitis at our surgical department in time period from 2015 to 2017. We compared the results of preoperative imaging examinations (ultrasound, CT) and intraoperative diagnosis (from the surgical record) with final histopathological findings.

Results: 386 patients were operated on for acute appendicitis. Histopathological examination revealed 33 patients (9%) with no signs of inflammation, 309 patients (80%) with inflammatory changes, 37 cases (10%) with chronic appendicitis and 7 other histological findings (2%). Ultrasound was performed in 382 patients (99%). False negative ultrasound was obtained in 18 (6%) of 309 patients with histologically confirmed inflammation. Ultrasound gave a false positive finding in 16 (48%) of 33 patients whose histology revealed no signs of inflammation. Equivocal ultrasound was obtained in 104 patients (27%). Intraoperative diagnosis of appendix without inflammation was described by the surgeon in 27 patients (7%). Of these, 12 cases (44%) were histologically non-inflammatory, 7 cases (26%) with acute inflammation, 7 cases (26%) with chronic inflammation and 1 other finding (4%).

Conclusion: Ultrasound is a suitable imaging method to confirm the diagnosis of acute appendicitis but not to rule it out. Intraoperative assessment of the appendix by the surgeon is not reliable. Any appendix intraoperatively evaluated as showing no signs of inflammation should be removed.