Diagnostic Process Using Endoscopy for Biliary Strictures: A Narrative Review

Abstract

The diagnostic process for biliary strictures remains challenging in some cases. A broad differential diagnosis exists for indeterminate biliary strictures, including benign or malignant lesions. The diagnosis of indeterminate biliary strictures requires a combination of physical examination, laboratory testing, imaging modalities, and endoscopic procedures. Despite the progress of less invasive imaging modalities such as transabdominal ultrasonography, computed tomography, and magnetic resonance imaging, endoscopy plays an essential role in the accurate diagnosis, including the histological diagnosis. Imaging findings and brush cytology and/or forceps biopsy under fluoroscopic guidance with endoscopic retrograde cholangiopancreatography (ERCP) are widely used as the gold standard for the diagnosis of biliary strictures. However, ERCP cannot provide an intraluminal view of the biliary lesion, and its outcomes are not satisfactory. Recently, peroral cholangioscopy, confocal laser endomicroscopy, endoscopic ultrasound (EUS), and EUS-guided fine-needle aspiration have been reported as useful for indeterminate biliary strictures. Appropriate endoscopic modalities need to be selected according to the patient's condition, the lesion, and the expertise of the endoscopist. The aim of this review article is to discuss the diagnostic process for indeterminate biliary strictures using endoscopy.

Keywords: ERCP; EUS; EUS-FNA; biliary strictures; cholangioscopy; confocal laser endomicroscopy; endoscopic retrograde cholangiopancreatography; endoscopic ultrasound.

Figure 1

Procedures of cholangiography and intraductal ultrasound (IDUS): (a) computed tomography showing the wall thickness in the bile duct (pink arrow); (b) cholangiography showing the biliary stricture in the hilar bile duct (pink arrow); the proximal part of the bile duct shows dilatation; (c) IDUS showing dilatation in the proximal part of the bile duct and no lesion; (d) IDUS showing a lesion in the biliary stricture (pink arrow).

Figure 2

Visual findings of cholangioscopy: (a) irregular thick tortuous vessels, suggesting malignancy; (b) irregular papillogranular surface, suggesting malignancy; (c) fine network of thin vessels, suggesting a benign lesion; (d) lower homogeneous papillogranular surface without primary masses, suggesting a benign lesion.

Figure 3

Procedures of peroral cholangioscopy (POCS) and biopsy under direct view with POCS: (a) cholangiography showing the biliary stricture in the distal bile duct (pink arrow); (b) POCS showing an irregular papillogranular surface at the stricture, suggestive of malignancy; (c) POCS showing a fine network of thin vessels at the hilar bile duct, suggesting no malignancy; (d) forceps biopsy under direct view with POCS; the histological examination revealed adenocarcinoma.

Figure 4

Probe-based confocal laser endomicroscopy images for biliary strictures: (a) thick dark bands (>40 µm) (pink arrow) according to the Miami classification; (b) dark clumps (pink arrow) according to the Miami classification; (c) reticular network of thin dark branching bands (<20 µm) according to the Miami classification.

Figure 5

Procedure of probe-based confocal laser endomicroscopy (pCLE) under direct view with peroral cholangioscopy (POCS) to diagnose biliary strictures: (a) cholangiography showing the biliary stricture in the hilar bile duct (pink arrow); (b) POCS showing irregular thick tortuous vessels at the stricture, suggestive of malignancy; (c,d) pCLE under direct view with POCS showing dark clumps, suggestive of malignancy; the histological examination demonstrated adenocarcinoma.

Figure 6

Diagnostic algorithm for indeterminate biliary strictures.