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Chandrasekar et al. Mini-invasive Surg 2021;5:33 https://dx.doi.org/10.20517/2574-1225.2021.12 Page 7 of 16

Figure 2. Endoscopic ultrasound demonstrating (A) mass in the distal bile duct in a patient with cholangiocarcinoma (B) fine needle
aspiration of the mass.

be passed over a guidewire into the bile duct enabling direct visualization, with the ability to perform
suction, irrigation and biopsies with specialized forceps (SpyBite) . The presence of an obvious mass
[49]
(nodular or papillary), abnormal blood vessels which are dilated and tortuous, irregularity in the surface can
be predictive of malignancy [Figure 3]. Pereira et al. in their retrospective study showed a visual accuracy
[50]
of 95.1% for the diagnosis of malignancy with a sensitivity of 100% and specificity of 89.5%. The SpyBite’s
accuracy was 80.5% with a sensitivity of 64% and specificity of 100%. Evaluation by cholangioscopy changed
the Bismuth classification in 42% of patients compared to imaging prior to the study. Other studies have
[53]
shown a higher sensitivity for SpyBite up to 86% [51,52] . Varadarajalu et al. in their retrospective study of 31
patients with indeterminate biliary strictures, demonstrated that the sensitivity could be increased to 94%
using rapid on-site examination with cytology . A randomized controlled trial (RCT) by Bang et al.
[55]
[54]
comparing patients undergoing cholangioscopy guided biopsies for indeterminate biliary strictures with
onsite vs offsite processing techniques demonstrated similar diagnostic accuracy, sensitivity and specificity
for both techniques, but the median number of biopsies to establish diagnosis was lower in the onsite group.

Studies have reported higher morbidity and rate of complications with cholangioscopy with up to five times
higher rates of cholangitis in these patients. A meta-analysis including more than 2000 patients reported an
adverse event rate of 7% with a serious adverse event rate of 1% . The role of direct cholangioscopy in the
[56]
diagnostic algorithm [Figure 4] for biliary cancers is still being investigated given the complexity,
availability, procedural duration, costs, and complications. It is a valuable tool for the investigation of
indeterminate biliary strictures with prior ERCPs inconclusive for malignancy when the clinical suspicion is
high.

Treatment
Therapy for malignant biliary strictures depends primarily on the level of obstruction (hilar vs. distal) and if
the malignancy is resectable or not. The treatment goal for biliary malignancies is providing a surgical cure
if the cancer is resectable or promoting biliary drainage in unresectable cancers. With advances in the field
of interventional endoscopy and ERCP, biliary drainage can be achieved in most patients thus improving
the quality of life.

Resectable cancers
Hyperbilirubinemia was thought to be associated with poorer surgical outcomes and hence earlier studies
focused on biliary drainage pre-operatively to reduce the risk by the placement of biliary stents
endoscopically . More recent data in the form of RCT have not shown any benefit in mortality for patients
[57]