Bile aspiration cytology in diagnosis of bile duct carcinoma: factors associated with positive yields

In bile duct carcinoma (BDC) patients, bile aspiration cytology (BAC) is an established method for cytodiagnosis. However, almost all previous reports investigated the biliary strictures caused not only by BDC but also by gallbladder and pancreatic carcinomas. Therefore, BAC in BDC patients only has not yet been investigated sufficiently. The aim of this study was to evaluate the actual sensitivity of BAC and to evaluate the factors that affect positive yields of BAC in patients with defined BDC. Data on 47 consecutive patients with definite BDC, who underwent BAC via endoscopic nasobiliary drainage (ENBD) or percutaneous transhepatic cholangiodrainage (PTCD), were retrospectively collected. Fourteen factors were studied for association with positive BAC. The number of cytological samplings ranged from 1 to 14 times. The cumulative diagnostic yield was 72.3% (34/47), and 32 positive results were obtained at a maximum of six samplings. Independent factors associated with positive BAC were perihilar location, stricture length a parts per thousand yen2 cm, and macroscopic papillary type. In BDC patients with ENBD or PTCD, repeated BAC is useful, and six times was the optimum number of repeat samplings. Although the sensitivity of BAC is not sufficient for the preoperative diagnosis of malignant biliary stricture, the three independent factors noted above predict positive yields and indicate whether or not BAC should be repeated up to six times.