Clinical significance of bile cytology via an endoscopic nasobiliary drainage tube for pathological diagnosis of malignant biliary strictures

In patients in whom there is a suspicion of malignant biliary strictures, bile cytology via an endoscopic nasobiliary drainage tube (ENBD cytology) is often performed, in addition to aspirated bile cytology, brush cytology, and forceps biopsy, during the initial endoscopic retrograde cholangiopancreatography (ERCP). We aimed to reveal the significance of ENBD cytology for the pathological diagnosis of malignant biliary strictures. We studied 214 patients with malignant biliary strictures. We performed aspirated bile cytology, brush cytology, and forceps biopsy in 93, 130, and 114 patients, respectively. ENBD cytology was performed one or more times in 79 patients. We examined the sensitivity of each sampling method, and analyzed the utility of ENBD cytology. The sensitivities of each sample acquisition method were as follows: 30% (28/93) for aspirated bile cytology, 48% (62/130) for brush cytology, 41% (47/114) for forceps biopsy, and 24% (19/79) for ENBD cytology. In 19 patients who showed positive ENBD cytology, other methods were performed in 11. Aspirated bile cytology, brush cytology, and forceps biopsy, were performed in 7, 5, and 6 patients, and the results were negative in 3 (43%), 2 (40%), and 1 (17%) patient, respectively. Three patients showed positive results only on ENBD cytology. Although the sensitivity of ENBD cytology was inferior to that of the other methods used, ENBD cytology may contribute to the improvement of the total diagnostic sensitivity for malignancy.