Interobserver Agreement Between a Radiology Resident and a Senior Sonologist in the Ultrasonographic Interpretation of Common Gallbladder Pathologies: A Cross-Sectional Observational Study
DOI:
https://doi.org/10.52206/jsmc.2026.16.3.1485Abstract
Background: Ultrasonography is the first-line imaging modality for gallbladder disease because it is safe, inexpensive, widely available, and provides real-time hepatobiliary assessment. However, its diagnostic accuracy is operator dependent, making interobserver agreement important for evaluating reliability in routine practice.
Objective: To evaluate the level of interobserver agreement between a radiology resident and a senior sonologist in the ultrasonographic interpretation of common gallbladder pathologies.
Methodology: This cross-sectional observational study was conducted in the Department of Radiology, Rehman Medical Institute, Peshawar, Pakistan, from March 2022 to June 2025. A total of 150 consecutive adult patients with clinically suspected gallbladder disease were enrolled. Each participant underwent two independent ultrasonographic examinations performed separately by a radiology resident and a senior sonologist, both blinded to each other's findings. Six predefined gallbladder abnormalities, including gallstones, biliary sludge, gallbladder wall thickening, polyps, pericholecystic fluid, and comet-tail artifact, were evaluated using standardized operational definitions. Interobserver agreement was assessed using Cohen's kappa (κ) coefficient with corresponding 95% confidence intervals.
Results: Gallstones demonstrated almost perfect agreement between observers (κ = 0.826; 95% CI: 0.735–0.917), while gallbladder polyps showed moderate agreement (κ = 0.581; 95% CI: 0.450–0.712). Fair agreement was observed for gallbladder wall thickening (κ = 0.392), biliary sludge (κ = 0.365), comet-tail artifact (κ = 0.341), and pericholecystic fluid (κ = 0.333). Agreement was consistently higher for objectively identifiable structural abnormalities than for subtle inflammatory or artifact-related findings.
Conclusion: Interobserver agreement in gallbladder ultrasonography varies according to the sonographic abnormality being evaluated. Gallstones demonstrate excellent reproducibility, whereas inflammatory and artifact-related findings remain susceptible to observer variability. Standardized scanning protocols, structured reporting systems, and focused training of radiology residents may improve consistency and reliability in gallbladder ultrasound interpretation.
Keywords: Cholelithiasis, Diagnostic Imaging, Gallbladder Diseases, Observer Variation, Reproducibility of Results, Ultrasonography.
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