Introduction: The differential diagnosis between malignant and benign biliary strictures is the cornerstone of the management of jaundiced patients. The aim of our study is to define the role of cytology of the bile withdrawn during endoscopic retrograde cholangiopancreatography (ERCP), to reach a diagnosis of the nature of biliary stricture.
Patients and methods: This retrospective study was conducted on 67 consecutive patients affected of ingravescent obstructive jaundice who underwent ERCP+/-PTE (percutaneous transhepatic endoscopic)+bile withdrawn+stenting. We founded hilar stricture in 21 patients (31.3%), middle third the common duct stricture in 17 (25.3%), and lower third stricture in 28 patients (41.4%). In one patient (2%) the cholangiography did not show any stricture, but we continued with the withdrawn of bile after positioning a naso-biliary drainage.
Results: Diagnosis was made in only 40 of 65 patients (61.5%) and no epithelial lining cells of the biliary tree was found in the remaining 25 patients (38.5%). The presence of neoplasm in the pancreato-biliary tract was excluded (absence of malignant cells) in 25 of 40 diagnostic exams (62.5%). During follow-up only 7 of these 25 patients resulted in having a benign disease (true negatives 28%) while the remaining 18 cases were diagnosed with malignant neoplasm of the pancreato-biliary tract (false negatives 72%). Nine of 14 with positive cytology for carcinoma were diagnosed with cholangiocarcinoma (65%), 4 with pancreatic (28%) and 1 with ampullary carcinoma. Of 25 non-diagnostic samples, 5 (20%) resulted as benign, 20 (80%) as malignant. The statistical analysis by chi-square test allowed us to conclude that bile cytology, if diagnostic, is significantly valid in identifying carcinoma of the pancreato-biliary tract (p<0.05) instead, considering the high rate of non diagnostic samples, its meaning is limited (p=0.09).
Discussion: Exfoliative cytology of bile samples obtained during ERCP is easier and less invasive method to determine the diagnosis of biliary strictures, but due to its low sensibility, varying from 6 to 63%, it doesn't appear accurate to establish a definite diagnosis; the stricture dilatation before the withdrawal increases the diagnostic sensibility and accuracy of the cytological exam.
Conclusion: Bile withdrawn for cytology during ERCP is a safe method with no increasing in patient's morbidity. It allows a diagnostic orientation in 75% of the patients. Bile withdrawn after dilatation of stricture allows improves sensibility and accuracy. Negative results does not exclude malignant disease, however, if positive, it is considered diagnostic (positive predictive value 100%).