The diagnostic accuracy of transabdominal ultrasonography needs to be considered when managing gallbladder polyps

Abstract

Background: Transabdominal ultrasonography (TAUS) is the most commonly used modality to diagnose gallbladder (GB) disease. GB polyps are reported in 1-5.6 % of TAUS studies. Histopathologic studies suggest that there is a relationship between GB polyps and GB cancer. Previous literature suggests GB polyps reported on TAUS do not correlate well with histological findings. There have been recent advances in TAUS technology. We hypothesize the recent advances in TAUS technology have improved the accuracy of TAUS for diagnosing GB polyps.

Methods: Radiology and pathology databases at our tertiary care center were retrospectively searched between January 1, 2000, and December 31, 2010. Ultrasound reports that suggested a GB polyp was present on TAUS were correlated to histopathology in cases where a cholecystectomy was performed. The pathology reports where a GB polyp was found were correlated with preoperative TAUS reports.

Results: There were 102,740 TAUS reports referring to the GB, of which 6,612 (6.4 %) contained search terms suggesting a GB polyp was present. There were 13,278 cholecystectomy pathology reports, of which 159 (1.2 %) included a diagnosis of GB polyp. TAUS detected only 50 % of the polyps identified on histopathology. The sensitivity and specificity of TAUS for diagnosing GB polyps were 50.0 and 98.3 %, respectively. The positive and negative predictive values were 10.5 and 99.8 %.

Conclusions: Despite improvement in TAUS technology, the accuracy for GB polyps remains poor. This needs to be considered when managing patients with TAUS-detected GB polyps. We recommend that the decision to operate on TAUS-detected GB polyps be largely based on symptoms, and following GB polyps with TAUS should be discouraged.