Post written by Mohan Ramchandani, MD, from the Asian Institute of Gastroenterology Hospitals, Hyderabad, India.

The aim of this study was to assess the diagnostic accuracy of digital single-operator cholangioscopy (DSOC) compared with ERCP-based assessment using traditional sampling technology in patients with indeterminate biliary strictures (IBS). Indeterminate biliary stricture was defined as a suspected intrinsic biliary stricture of unknown entity (benign or malignant) based on prior MRCP.

Characterization of intra-ducal biliary lesions always pose a challenge to endoscopists. Conventionally, ERCP is used as the first modality to evaluate patients presenting with obstructive jaundice with imaging evidence of a biliary stricture and intrahepatic ductal dilatation. These cholangiographic images obtained often are non-diagnostic, and the inability to differentiate benign from malignant is the major limitation of radiological studies. Moreover, the brush cytology samples obtained during ERCP have dismally low diagnostic yield. These patients ultimately may either undergo repeated ERCPs for final diagnosis, delaying the definitive treatment, or are subjected to potentially avoidable surgical resections. DSOC is now commonly used during ERCP to interrogate a biliary stricture where diagnosis is difficult to establish with conventional methods. DSOC provides high-resolution direct visualization of the bile duct and allows for tissue acquisition and thus is an attractive option to increase diagnostic accuracy in IBS.

This randomized control trial comparing DSOC to standard ERCP techniques in the evaluation of IBS has shown that DSOC is safe and effective and has a higher sensitivity in the visual and histopathological diagnosis of such lesions. Our study emphasized 2 aspects where DSOC can be of enormous help in establishing a diagnosis in patients with IBS. The first one is getting visual impression of the stricture, and second is DSOC-guided targeted biopsy. There is major benefit in having visual impression of the stricture ERCP as it gives the operator further information about the lesion, which has an impact on patient management such as planning further investigation or therapy despite negative or indeterminate histopathology results. DSOC-based visual impression of the IBS provided a higher diagnostic accuracy, sensitivity, and positive predictive value compared with conventional ERCP cholangiography without a difference in adverse events.

The second aspect was DSOC-guided tissue acquisition, our study found that compared with standard ERCP-based tissue acquisition, DSOC-guided evaluation had a higher sensitivity in the histologic diagnosis of IBS. In our study, the sensitivity with DSOC was 68% compared with 21% with ERCP-guided brushing. Based on the results of our study, it appears that combining the direct cholangioscopic visual impression with DSOC-guided biopsy sampling provides the highest chance of confirming the diagnosis in IBS. The role of directly going with DSOC-guided assessment of biliary strictures without prior conventional ERCP-guided tissue acquisition needs to be explored further with larger randomized trials.

Further innovations in cholagioscopic characterization of strictures, higher resolution of acquired images, better tissue acquisition devices, and possible role of artificial intelligence in interpreting images are desirable and will improve our understanding in this field even further.

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