Indeterminate biliary strictures pose a diagnostic challenge. The main reason for this has been the inability to obtain adequate tissue from the site of the biliary stricture. ERCP along with brush cytology has been the traditional method of obtaining cytology specimens, but has been found to have poor sensitivity. Cholangioscopy provides the ability to obtain biopsies under direct visualisation from these strictures. We aimed to compare the diagnostic utility of ERCP and brush cytology with cholangioscopy and biopsy. We also correlated visual findings on cholangioscopy with benign and malignant strictures

In this prospective observational study, we included patients with indeterminate biliary strictures who underwent ERCP from April 2020 to April 2021.Indeterminate biliary stricture was defined as absence of diagnosis following cross sectional imaging and MRCP. Patients underwent back-to-back ERCP with brush cytology followed by cholangioscopy with biopsy during the same session. Data regarding biochemical, imaging, ERCP-BC and SOC guided biopsy were recorded. The appearance of the stricture on cholangioscopy was recorded. The final diagnosis of malignancy vs benign stricture was ascertained on positive pathology or on follow up for 3 months. The diagnostic accuracy of each modality was then calculated.

A total of 25 patients with indeterminate biliary strictures were included in the study, with a median age of 58.84 ± 15.69 years with 36% being females. The sensitivity, specificity, positive predictive value,negative predictive value and accuracy of ERCP-BC and SOC guided biopsy  was 55.6%,100 %,100%, 80%, 84% (p-value = 0.002) and  77.8%,100%,100% ,88.8%, 92% (p-value < 0.001) respectively.Nodularity,presence of mass like appearance and irregular dilated vessels seen on cholangioscopy best predicted malignancy. Adverse events were similar in both groups

SOC guided biopsy had better sensitivity and diagnostic accuracy when compared to brush cytology in diagnosis of malignancy in indeterminate hilar biliary strictures. SOC had a added advantage of direct visualisation of the stricture for features of malignancy