Abstract
Background : The sensitivity of bile cytology is recognized as being low. Repeating cytological sampling is likely to improve the sensitivity. We studied the usefulness of bile cytology obtained via an endoscopic nasobiliary drainage (ENBD) tube. Moreover, the frequency of the cytological examinations to obtain a positive rate of 95% or more was examined.
Methods : One hundred and thirty-three patients were enrolled in the study who had attended Hiroshima Red Cross and Atomic-bomb Survivors Hospital with malignant biliary stricture, with an indwellng ENBD tube, from May 2004 to February 2009. Diagnoses included pancreatic carcinoma (n = 49), bile duct carcinoma (n = 39), gallbladder carcinoma (n = 20), cholangiocellular carcinoma (n = 12), carcinoma of the major papilla (n = 7), and other malignancies (n = 6).
Results : The mean number of cytological examinations was 3 (range, 2-9). In 42 of 133 patients, cytology was positive at the first examination (sensitivity 31.6%). Cytology was cumulatively positive in 73 of 133 patients (sensitivity 54.9%). The sensitivity of bile duct carcinoma was 66.7% and that of pancreatic carcinoma was 42.9%. A significant difference of p=0.03 was recognized between the two groups. In 70 of 73 (97.2%) patients with positive cytology, positive results were obtained by the sixth or less examination. In both bile duct carcinoma and pancreatic carcinoma, the positive rate became 95% or more by the sixth examination (Bile duct carcinoma : 96.2%, pancreatic carcinoma : 95.2%).
Conclusion : Bile can be obtained repeatedly via an ENBD tube and that contributes to improve the diagnostic accuracy. The optimal number of repeated cytological samplings to obtain a positive rate of 95% or more was concluded to be 6.
