BACKGROUND: Consequences of incidental gallbladder cancer (iGBC) following cholecystectomy may include repeat operation (depending on T stage) and worse survival (if bile spillage occurred), both avoidable if iGBC were suspected preoperatively.

METHODS: A retrospective single-institution review was done. Ultrasound images for cases and controls were blindly reviewed by a radiologist. Chi-square and Student's t tests, as well as logistic regression and Kaplan-Meier analyses were used. A P?≤?0.01 was considered significant.

RESULTS: Among 5796 cholecystectomies performed 2000-2013, 26 (0.45%) were iGBC cases. These patients were older (75.61 versus 52.27 years), had more laparoscopic-to-open conversions (23.1% versus 3.9%), underwent more imaging tests, had larger common bile duct diameter (7.13 versus 5.04?mm) and higher alkaline phosphatase. Ultrasound imaging showed that gallbladder wall thickening (GBWT) without pericholecystic fluid (PCCF), but not focal-versus-diffuse GBWT, was associated significantly with iGBC (73.9% versus 47.4%). On multivariable logistic regression analysis, GBWT without PCCF, and age were the strongest predictors of iGBC. The consequences iGBC depended significantly on intraoperative bile spillage, with nearly all such patients developing carcinomatosis and significantly worse survival.

CONCLUSIONS: Besides age, GBWT, dilated common bile duct, and elevated alkaline phosphatase, number of preoperative imaging modalities and the presence of GBWT without PCCF are useful predictors of iGBC. Bile spillage causes poor survival in patients with iGBC.