We thank Drs Kulpafcharapong and Rerknimitr
1
for their important comments on our study.2
An indeterminate biliary stricture can be defined on the basis of cross-sectional imaging appearance, on the basis of sampling, or on both. The aim of our study was to identify the comparative accuracies of single-operator cholangioscopy (SOC)-guided biopsies and ERCP-based transpapillary brushing (TPB) on the basis of an indeterminate stricture on cross-sectional appearance alone. To determine which sampling modality has higher accuracy at first intervention, we excluded patients who had previously undergone TPB. Because of the major differences in treatments constituting endoscopic intervention, medical treatment, extensive surgery, and palliation, a correct diagnosis, preferably at first ERCP, is crucial for the patient’s prognosis and treatment.2
In addition, it may be unethical to randomize patients who have an indeterminate stricture after TPB to yet another round of TPB. Furthermore, the visual interpretation of digital SOC may potentially be affected if there has been prior intervention such as TPB. To clarify which diagnostic modality is superior at first intervention, we thought we needed to exclude patients with prior TPB/sampling. Furthermore, it is difficult to compare the sensitivity of TPB in our study with that in other studies because they were not necessarily controlled or prospective and were often based on an older-generation imaging platform.We agree that ERCP with TPB may still be a standard procedure in many units in those cases, but we are not sure, looking at the currently published and very promising results of SOC-guided biopsy examinations, whether that will remain the case for this selected group of patients.
2
, 3
, 4
, 5
, 6
, 7
, 8
, 9
, 10
The pooled sensitivity in the review cited by Drs Kulpafcharapong and Rerknimitr1
showed results below 50% with no significant difference between transpapillary brushing (45%) and biopsies (48%).11
This review included several mixed populations (pancreatic cancer, ampullary adenocarcinoma, and cholangiocarcinoma), and the authors themselves stated that they could not tell “specific sensitivities of the modalities in detecting different malignancies….”11
Therefore, the authors are concerned that we studied the wrong population, while at the same time referring to studies that combined many different populations. Looking even deeper into this review, we can see that the 2 largest patient cohorts included had a sensitivity for brushing of only 35% and 26%.11
In addition, we believe that a procedure with a sensitivity that is lower than the chance of flipping a coin cannot determine or define a “true” indeterminate stricture. Thus, to be absolutely correct in our study, the stricture is indeterminate at the level of cross-sectional imaging, inasmuch as we already here cannot say whether it is malignant or benign and remains indeterminate if the first procedure fails (see Table 3 in the article by Gerges et al).2
Regarding the systematic review by Navaneethan et al,
8
we would like to emphasize several important points. A comparison of fiberoptic SOC data with digital SOC data is not really applicable because these are 2 very different devices, and the diagnostic odds ratio in that review mentioned by Kulpafcharapong and Rerknimitr1
was applicable for only 4 of the investigated 10 studies. Besides, the authors of that review themselves state that only 1 included study compared the yield of SOC biopsies in a paired cohort design with standard brushings and biopsies. In this study, SOC biopsies had a sensitivity of 76.5% compared with brushings (5.8%) and biopsies (29.4%).3
,8
Looking at this study, in particular, one can ask what value a definition has if the results in 94.2% of the population still remain unclear after the defining procedure. Would it not be more correct to define it as indeterminate from the beginning?Looking deeper into the published data, we believe that our findings reflect our personal experience in patients with intrinsic biliary strictures and confirm previous published experiences alike. We believe our study demonstrates that the utility of digital SOC for indeterminate strictures and that further studies, including those of cost effectiveness, will help to establish its exact role in the diagnosis of indeterminate strictures.
References
- Indetermination of indeterminate biliary strictures.Gastrointest Endosc. 2020; 91: 1215
- Digital single-operator peroral cholangioscopy-guided biopsy versus ERCP-guided brushing for indeterminate biliary strictures: a prospective, randomized multicenter trial (with video).Gastrointest Endosc. 2020; 91: 1105-1113
- Diagnostic accuracy of conventional and cholangioscopy-guided sampling of indeterminate biliary lesions at the time of ERCP: a prospective, long-term follow-up study.Gastrointest Endosc. 2012; 75: 347-353
- Per oral cholangiopancreatoscopy in pancreatico biliary diseases--expert consensus statements.World J Gastroenterol. 2015; 21: 4722-4734
- The economic impact of using single-operator cholangioscopy for the treatment of difficult bile duct stones and diagnosis of indeterminate bile duct strictures.Endoscopy. 2018; 50: 109-118
- Peroral cholangioscopy with cholangioscopy-directed biopsies in the diagnosis of biliary malignancies: a systemic review and meta-analysis.Eur J Gastroenterol Hepatol. 2019; 31: 935-940
- Is single-operator peroral cholangioscopy a useful tool for the diagnosis of indeterminate biliary lesion? A systematic review and meta-analysis.Gastrointest Endosc. 2015; 82: 79-87
- Single-operator cholangioscopy and targeted biopsies in the diagnosis of indeterminate biliary strictures: a systematic review.Gastrointest Endosc. 2015; 82: 608-614.e2
- Role of single-operator peroral cholangioscopy in the diagnosis of indeterminate biliary lesions: a single-center, prospective study.Gastrointest Endosc. 2011; 74: 511-519
- Single-operator cholangioscopy in patients requiring evaluation of bile duct disease or therapy of biliary stones (with videos).Gastrointest Endosc. 2011; 74: 805-814
- Comparative effectiveness of biliary brush cytology and intraductal biopsy for detection of malignant biliary strictures: a systematic review and meta-analysis.Gastrointest Endosc. 2015; 81: 168-176
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- Indetermination of indeterminate biliary stricturesGastrointestinal EndoscopyVol. 91Issue 5
