BACKGROUND:It is often difficult to distinguish gallbladder cancers (GBC) from benign gallbladder diseases, which show thickened walls. OBJECTIVES:To evaluate the efficacy of bile cytology using endoscopic transpapillary gallbladder drainage (ETGD) and CT. DESIGN:Retrospective study. SETTING:Division of Gastroenterology, Tokyo Medical University, Tokyo, Japan. PATIENTS AND INTERVENTIONS:Eighty-five patients with gallbladder diseases, consisting of 27 GBC and 58 benign gallbladder diseases, were reviewed. A pigtail-type nasobilliary drainage tube was left indwelling in the gallbladder, and through this drainage tube washing cytology was performed with an ETGD tube. MAIN OUTCOME MEASUREMENTS:Diagnostic accuracy of CT and cytology. Complications and outcome were also evaluated. RESULTS:CT and cytology with the ETGD tube had 81% and 81% sensitivity, 91% and 83% specificity, and 88% and 82% accuracy, respectively (P > .05). Looking only at the 71 successful ETGD cases, CT and ETGD cytology had 82% and 100% sensitivity, 92% and 98% specificity, and 89% and 99% accuracy, respectively (P = .036 and .025, respectively). Four patients with GBC in whom CT showed benign findings underwent open cholecystectomy because ETGD cytology revealed malignant findings. In contrast, 4 patients with benign diseases in whom CT suggested malignant finding underwent LC because the findings of ETGD cytology suggested benign disease. CONCLUSIONS:Cytology using an ETGD tube is very useful in the diagnosis and management of gallbladder diseases.