Probe-based confocal laser endomicroscopy for the diagnosis of indeterminate biliary strictures

Indeterminate biliary strictures frequently present as a diagnostic conundrum given the suboptimal accuracy rates of current sampling techniques. They are defined as those observed on at least one imaging modality with negative cytopathologic evaluation on previous sampling attempts (brushings and/or endobiliary biopsy) during endoscopic retrograde cholangiopancreatography in the absence of an alternative cause. Various novel sampling techniques (cholangioscopy-directed biopsies) and advanced imaging technologies (cholangioscopy, confocal laser microscopy, and narrow band imaging) have been described in the evaluation of indeterminate biliary strictures. Probe-based confocal laser microscopy (pCLE) is at the forefront of these techniques and provides microscopic information in real time incorporating dynamic information such as blood flow, cellular architecture, contrast uptake, and leakage.

Standardized classification of pCLE findings of biliary strictures has been proposed. Initial observational studies have reported encouraging data specifically with regard to the sensitivity and negative predictive value of the pCLE findings in diagnosing malignancy.

Initial results are encouraging with the eventual hope of expediting malignancy detection to enhance management options of patients with biliary malignancy. Further, if pCLE findings are benign, this can reassure both patient and provider. Multicenter prospective trials are underway to further validate criteria and define the role of this technology compared with conventional tissue sampling techniques in the diagnostic algorithm for indeterminate biliary strictures.