The utility of ultrasonography compared to surgical and pathology findings in evaluating suspected acute appendicitis at a tertiary institution in Kenya

Abstract

Objective: To investigate the role of ultrasonography in evaluating patients with clinical suspicion of acute appendicitis.

Design: A prospective descriptive study of patients clinically suspected to have acute appendicitis. The abdominal sonographic findings were correlated to the surgical and pathology results.

Setting: Kenyatta National Hospital and the Department of Diagnostic Imaging and Radiation Medicine, University of Nairobi.

Subjects: Patients with a clinical suspicion of acute appendicitis referred for abdominal ultrasonography during the study period.

Results: A total of 112 patients were recruited following ethical approval and informed consent. Males were 73 and females 39 giving a male to female ratio of 1.9:1. The age distribution was from 8 to 70 years with a median age of 27.1 years (IQR 11.5, Q1 = 19.6, Q3=37.1). All patients presented with abdominal pain which was localized at the right iliac fossa in 96 (86%) patients and generalized in 16 (14%). Ultrasound examination of abdomen showed that 97 (87%) patients had findings concerning for appendicitis. The rest (15) patients did not have sonographic features concerning for appendicitis. All patients underwent appendicectomy and 61(54.5%) had inflamed appendices, 32 (28.6%) perforated appendices, 27(24.1%) abscess and 5(4.5%) were gangrenous. The histology of the excised appendices resulted in accuracy, sensitivity, specificity, PPV and NPV of sonographic diagnosis of acute appendicitis to be 88.4%, 92%, 58.3%, 95% and 47% respectively. The overall negative appendicectomy rate was 10.7%.

Conclusion: Abdominal ultrasonography using graded compression technique is a useful tool for evaluation of suspected acute appendicitis. However, the ultrasound findings should always be carefully correlated with clinical findings since its negative predictive value is quite low (47%).