Ultrasound as a First-Line Modality for Acute Colonic Diverticulitis: A Prospective Comparison with CT

Objectives: We aimed to compare the accuracy of ultrasound and computed tomography (CT) for the diagnosis of patients with suspected acute diverticulitis and to determine if ultrasound might serve as the primary tool for this purpose in the emergency department. Methods: A double-blind prospective study design was used. The study group included 142 consecutive patients with clinically suspected diverticulitis admitted to the emergency department of a tertiary medical center in 2016-2019. All underwent first ultrasound examination followed by abdominal CT. The final diagnosis was interpreted independently by an expert radiologist in a blinded fashion. Imaging data were compared with final diagnosis and we analyzed the findings against the medical, clinical, and laboratory data. Results: The final diagnosis was colonic diverticulitis in 98 patients. Sensitivity was 93.8% for ultrasound and 100% for CT; corresponding specificity rates were 86.7% and 100%. Agreement between the modalities was excellent (kappa = 0.81). CT demonstrated complicated diverticulosis in 18 patients: 8 pericolic abscesses, 9 micro-perforations, and 1 fistula. Ultrasound missed one abscess and five micro-perforations; however, all were small and were treated conservatively. Twenty-three patients were found to have an acute abdominal condition other than diverticulitis; sensitivity in these cases was 60.8% for ultrasound and 91.3% for CT. In 21 patients, the diagnosis was unknown. Conclusions: Ultrasound has similar sensitivity and specificity to CT for the diagnosis of acute colonic diverticulitis. We believe ultrasound may serve as the initial imaging modality in the emergency department, with CT reserved for large abscesses or inconclusive ultrasound findings.