Overtreatment of Nonneoplastic Gallbladder Polyps due to Inadequate Routine Ultrasound Assessment

Background: The primary aim was to assess the diagnostic accuracy of routine ultrasound assessment for gallbladder polyps. The secondary aim was to identify the characteristics that differentiate neoplastic polyps from nonneoplastic polyps. Methods: A total of 156 patients with histopathologically proven gallbladder polyps in 4 Dutch hospitals between 2003 and 2013 were included. Sensitivity and specificity of ultrasound for polyp size, number of polyps, and polyp type were assessed using histopathological findings as a reference standard. In addition, diagnostic accuracy of sonographic size >= 1 cm for neoplasia was assessed. Subgroup analysis for patients with polyps as primary indication for cholecystectomy was performed. The sonographic polyp characteristics on preoperative routine ultrasound were described. Results: Fifty-six percent of gallbladder polyps were preoperatively identified on ultrasound, of which 31% were neoplastic. Sensitivity and specificity of ultrasound to estimate polyp size were 93 and 43% (subgroup; 92 and 33%). Sensitivity and specificity of sonographic polyp size >= 1 cm for neoplasia were 86 and 32% (subgroup; 94 and 26%). No specific sonographic characteristics for neoplastic polyps could be established due to lack of reporting. Conclusion: Routine ultrasound assessment of polyps is associated with overestimation of polyp size and low specificity of sonographic size >= 1 cm for neoplasia, which contributes to surgical overtreatment of nonneoplastic polyps.