Effectiveness of a new long cytology brush in the evaluation of malignant biliary obstruction: a prospective study

The Catheter Flushing Method Shows a Similar Diagnostic Yield to the Conventional Method in Brushing Cytology for Biliary Strictures

Background/Objectives: Endobiliary brushing is usually performed in the diagnosis of indeterminate biliary strictures; however, in this setting, brush cytology is limited by a low diagnostic yield and sensitivity. Here, we compared the catheter flushing method (CFM) with the conventional cytologic method (CCM) in terms of cellularity and diagnostic performance. Methods: Endobiliary brushings were obtained during endoscopic retrograde cholangiopancreatography (ERCP) from patients with biliary strictures enrolled at six tertiary hospitals. Additionally, the CFM was performed after brushing. Using liquid-based cytologic preparations of samples, we assessed the diagnostic performance of the CCM using Pap staining and the CFM using methionyl-transfer RNA synthetase 1 (MARS1) immunofluorescence staining. Results: From a total of 399 patients (malignant, 253; benign, 146), 374 CCM samples and 361 CFM samples contained adequate cells, with no significant difference in diagnostic yield (93.7% vs. 90.5%, respectively; p = 0.088). The sensitivity of the CFM (90.3%) was significantly higher than that of the CCM (75.1%; p < 0.001), with no significant difference in accuracy between methods (81.2% vs. 82.6%, respectively; p = 0.608). Conclusions: The diagnostic yield of the CFM was comparable to that of the CCM. Additionally, the diagnostic performance of the CFM was comparable to that of the CCM. These findings indicate that the CFM could be an additional brush cytology method for sample collection in patients with indeterminate biliary strictures. Incorporating both the CCM and CFM might be expected to improve the diagnostic yield of brush cytology in the biliary strictures. Further prospective comparative studies between the CCM and CFM using the same staining method are needed to validate these findings.

Diagnostic Efficacy of a Novel Rotating Brush for Endoscopic Sampling of Malignant Biliary Strictures: A Multicenter Prospective Study

INTRODUCTION

Although cytologic examination of biliary stricture brushings obtained by endoscopic retrograde cholangiopancreatography is commonly used for diagnosing malignant biliary strictures (MBSs), it has low sensitivity. Several new brushes have capabilities that are still being debated. We have developed a novel brush working from conventional back-and-forth movement to rotation in situ (RIS) that may be more efficient for MBS sampling. We aimed to compare the MBS detection sensitivity of our RIS brush with that of the conventional brush.

METHODS

In this multicenter prospective study, we enrolled patients who underwent endoscopic retrograde cholangiopancreatography for suspected MBSs involving biliary stricture brushings obtained using our RIS brush. The historical control group consisted of the 30-brushing arm of our previous randomized trial (patient inclusion, 2018-2020) that used the study design in the same centers and with the same endoscopists as were used in this study. The primary outcome was to compare the sensitivity and specificity of detecting MBSs by cytologic evaluation of biliary stricture brushings between the 2 groups.

RESULTS

We enrolled 155 patients in the intent-to-treat analysis. Using the same number of brushing cycles, the RIS brush showed a higher sensitivity than the conventional brush (0.73 vs 0.56, P = 0.003). In per-protocol population, the sensitivity was also higher in the RIS brush group than in the conventional brush group (0.75 vs 0.57, P = 0.002). Multivariate analysis revealed that the RIS brush was the only predictive factor for MBS detection. No significant differences were observed in procedure-related complications between the 2 groups.

DISCUSSION

The RIS brush was a promising tool for effective and safe MBS sampling and diagnosis. Further randomized studies are warranted to confirm our results (Chictr.org.cn, identifier: ChiCTR2100047270).

Practice guidelines for managing extrahepatic biliary tract cancers

Backgrounds/Aims

Reported incidence of extrahepatic bile duct cancer is higher in Asians than in Western populations. Korea, in particular, is one of the countries with the highest incidence rates of extrahepatic bile duct cancer in the world. Although research and innovative therapeutic modalities for extrahepatic bile duct cancer are emerging, clinical guidelines are currently unavailable in Korea. The Korean Society of Hepato-Biliary-Pancreatic Surgery in collaboration with related societies (Korean Pancreatic and Biliary Surgery Society, Korean Society of Abdominal Radiology, Korean Society of Medical Oncology, Korean Society of Radiation Oncology, Korean Society of Pathologists, and Korean Society of Nuclear Medicine) decided to establish clinical guideline for extrahepatic bile duct cancer in June 2021.

Methods

Contents of the guidelines were developed through subgroup meetings for each key question and a preliminary draft was finalized through a Clinical Guidelines Committee workshop.

Results

In November 2021, the finalized draft was presented for public scrutiny during a formal hearing.

Conclusions

The extrahepatic guideline committee believed that this guideline could be helpful in the treatment of patients.

Mechanical Perspective on Increasing Brush Cytology Yield

Brush cytology is a sampling technique extensively used for mucosal surfaces, particularly to identify malignancies. A sample is obtained by rubbing the brush bristles over the stricture or lesion several times until cells are trapped. Brush cytology detection rate varies, with malignancy confirmed in 15-65% of cases of adenocarcinoma-associated biliary strictures and 44-80% of cases of cholangiocarcinoma. Despite the widespread use of brush cytology, there is no consensus to date defining the optimal biliary brushing parameters for the collection of suspicious lesions, such as the number of passes, brushing rate, and force applied. The aim of this work is to increase the brush cytology diagnostic yield by elucidating the underlying mechanical phenomena. First, the mechanical interactions between the brush bristles and sampled tissue are analyzed. During brushing, mucus and detached cells are transferred to the space between the bristles through the capillary rise and flow eddies. These mass transfer mechanisms and their dependence on mucus rheology as a function of pH, brush displacement rate, and bristle geometry and configuration are examined. Lastly, results from ex vivo brushing experiments performed on porcine stomachs are presented. Clinical practitioners from a variety of disciplines can apply the findings of this study to outline clear procedures for cytological brushing to increase the sensitivity and specificity of the brushings.

A Randomized Comparative Study of the Use of Individual Modality and Combination of Endoscopic Retrograde Cholangiopancreatography (ERCP) and Digital Single-Operator Cholangioscopy (DSOC) for Diagnosis of Indeterminate Biliary Strictures

BACKGROUND

To determine the superiority of the combination of endoscopic retrograde cholangiopancreatography (ERCP) and digital single-operator cholangioscopy (DSOC) in the same sitting over the individual modality alone in patients with indeterminate biliary strictures.

MATERIALS AND METHODS

A randomized study enrolled 60 adult patients with biliary strictures who were randomized into two groups: ERCP + DSOC and ERCP/DSOC. Histopathologic or cytologic assessment was performed in terms of benign, indeterminate, or malignant nature of the strictures. Procedural adverse events were documented. Accuracy in terms of sensitivity (Sn), specificity (Sp), and predictive value [positive (PPV) and negative (NPV)] were noted.

RESULTS

As per final diagnosis, in ERCP/DSOC group, there were 12 (40%) benign cases and 18 (60%) malignant cases, and in group ERCP + DSOC, there were 8 (26.67%) benign cases and 22 (73.33%) malignant cases. ERCP/DSOC labeled 16 (53.33%) patients as benign, 8 (26.67%) as malignant, and 6 (20%) as indeterminate, while ERCP + DSOC labeled 8 (26.67%) as benign, 17 (56.67%) as malignant, and 5 (16.67%) as indeterminate. The Sn, Sp, PPV, and NPV of ERCP/DSOC were 44.4%, 75%, 100%, and 56.25%, and for ERCP + DSOC was 77.27%, 62.50%, 100%, and 62.5%, respectively (P = 0.033). Side effects were statistically similar in both the groups (P > 0.05).

CONCLUSION

To conclude, the combination of ERCP with DSOC is safe and effective with higher diagnostic sensitivity (77.27%) in comparison to standard ERCP or DSOC alone (44.4%) for the diagnosis of biliary strictures.

Diagnostic performance and safety of endoscopic ultrasound-guided tissue acquisition of gallbladder lesions: A systematic review with meta-analysis

BACKGROUND

Endoscopic ultrasound (EUS)-guided tissue acquisition (TA) is widely used for various target samples, but its efficacy in gallbladder (GB) lesions is unknown. The aim of the present meta-analysis was to assess the pooled adequacy, accuracy and safety of EUS-TA of GB lesions.

METHODS

A literature search from January 2000 to August 2022 was done for studies analyzing the outcome of EUS-guided TA in patients with GB lesions. Pooled event rates were expressed with summative statistics.

RESULTS

The pooled rate of sample adequacy for all GB lesions and malignant GB lesions was 97.0% (95% CI: 94.5-99.4) and 96.6% (95% CI: 93.8-99.3), respectively. The pooled sensitivity and specificity for the diagnosis of malignant lesions were 90% (95% CI: 85-94; I2 = 0.0%) and 100% (95% CI: 86-100; I2 = 0.0%), respectively, with an area under the curve of 0.915. EUS-guided TA had a pooled diagnostic accuracy rate of 94.6% (95% CI: 90.5-96.6) for all GB lesions and 94.1% (95% CI: 91.0-97.2) for malignant GB lesions. There were six reported mild adverse events (acute cholecystitis = 1, self-limited bleeding = 2, self-limited episode of pain = 3) with a pooled incidence of 1.8% (95% CI: 0.0-3.8) and none of the patients had serious adverse events.

CONCLUSION

EUS-guided tissue acquisition from GB lesions is a safe technique with high sample adequacy and diagnostic accuracy. EUS-TA can be an alternative when traditional sampling techniques fail or are not feasible.

The multidisciplinary management of cholangiocarcinoma

Cholangiocarcinoma is a lethal malignancy of the biliary epithelium that can arise anywhere along the biliary tract. Surgical resection confers the greatest likelihood of long-term survivability. However, its insidious onset, difficult diagnostics, and resultant advanced presentation render the majority of patients unresectable, highlighting the importance of early detection with novel biomarkers. Developing liver-directed therapies and emerging targeted therapeutics may offer improved survivability for patients with unresectable or advanced disease. In this article, the authors review the current multidisciplinary standards of care in resectable and unresectable cholangiocarcinoma, with an emphasis on novel biomarkers for early detection and nonsurgical locoregional therapy options.

First interobserver agreement of optical coherence tomography in the bile duct: A multicenter collaborative study

Background and study aims  Optical coherence tomography (OCT) is a new technology available for evaluation of indeterminate biliary strictures. It allows under-the-surface visualization and preliminary studies have confirmed standardized characteristics associated with malignancy. The aim of this study is to evaluate the first interobserver agreement in identifying previously agreed upon OCT criteria and diagnosing of malignant versus benign disease. Patients and methods  Fourteen endoscopists were asked to review an atlas of reference clips and images of eight criteria derived from expert consensus A total of 35 de-identified video clips were then evaluated for presence of the eight criteria and for final diagnosis of malignant versus benign using the atlas as reference Intraclass correlation (ICC) analysis was done to evaluate interrater agreement. Results  Clips of 23 malignant lesions and 12 benign lesions were scored. Excellent interobserver agreement was seen with dilated hypo-reflective structures (0.85) and layering effacement (0.89); hyper-glandular mucosa (0.76), intact layering (0.81), and onion-skin layering (0.77); fair agreement was seen with scalloping (0.58), and thickened epithelium (0.4); poor agreement was seen with hyper-reflective surface (0.36). The diagnostic ICC for both neoplastic (0.8) and non-neoplastic (0.8) was excellent interobserver agreement. The overall diagnostic accuracy was 51 %, ranging from 43 % to 60 %. Conclusions  Biliary OCT is a promising new modality for evaluation of indeterminate biliary strictures. Interobserver agreement ranged from fair to almost perfect on eight previously identified criteria. Interobserver agreement for malignancy diagnosis was substantial (0.8). Further studies are needed to validate this data.

Clinical impact of a novel device delivery system in the diagnosis of bile duct lesions: A single-center experience

BACKGROUND AND AIM

Pathological evaluation is essential for the diagnosis of biliary tract diseases. However, existing evaluation methods have various challenges in terms of operability and diagnostic performance. The present study aimed to evaluate the feasibility, utility, and safety of a novel device delivery system for bile duct biopsy.

METHODS

This study was conducted as a retrospective, descriptive analysis at a single center. Overall, 25 examinations in 14 consecutive patients who underwent transpapillary biopsies for biliary lesions using the novel device delivery system from July to November 2020 were reviewed. Number and time of biopsy, technical success rate, adequate tissue sampling rate, adverse events, and diagnostic performance of bile duct biopsies using the novel device were evaluated. Moreover, negative surgical margins were assessed in patients who underwent surgical resection after mapping biopsy.

RESULTS

The median number of biopsy samples was five (range: 2-13), with a median biopsy time of 11.6 min. The technical success rate was 100% (140/140), with an adequate sampling rate of 82.9% (116/140). These rates did not differ depending on the biopsy site or purpose. There were no serious adverse events related to the procedures. The diagnostic sensitivity, specificity, and accuracy of biliary stricture were 90%, 100%, and 92.3%, respectively. Negative surgical margins were confirmed in all patients undergoing surgical resection, including one patient with a surgical procedure changed based on the results of mapping biopsy.

CONCLUSIONS

The novel device delivery system has potentials in diagnosing biliary tract diseases and determining appropriate treatment strategies.

Brush Cytology, Forceps Biopsy, or Endoscopic Ultrasound-Guided Sampling for Diagnosis of Bile Duct Cancer: A Meta-Analysis

Endoscopic sampling is essential for tissue diagnosis of cholangiocarcinoma (CCA). To evaluate and compare the diagnostic sensitivities of endoscopic retrograde cholangiopancreatography-guided brush cytology biopsy, and endoscopic ultrasound-guided fine needle aspiration (EUS-FNA) in patients with CCA. A comprehensive literature search through multiple databases was conducted for articles published between January 1995 and August 2020. The pooled rates of sensitivity for the diagnosis of CCA and of adverse events were compared among brushing, biopsy, brushing & biopsy, and EUS-FNA. In total, 1123 patients with CCA (32 studies), 719 patients (20 studies), 358 patients (13 studies), and 422 patients (17 studies) were tested by brushing, biopsy, brushing & biopsy, and EUS-FNA, respectively. The pooled diagnostic sensitivity was 56.0% (95% confidence interval (CI) 48.8-63.1%, I2 = 83.0%) with brushing, 67.0% (95% CI 60.2-73.5%, I2 = 72.5%) with biopsy, 70.7% (95% CI 64.1-76.8%, I2 = 42.7%) with brushing & biopsy, and 73.6% (95% CI 64.7-81.5%, I2 = 74.7%) with EUS-FNA. The diagnostic sensitivity was significantly lower for brushing than for biopsy, brushing & biopsy, or EUS-FNA. No significant difference was noted in diagnostic sensitivities among biopsy, brushing & biopsy, and EUS-FNA. Adverse events were comparable between the groups. Intraductal biopsy, brushing & biopsy, and EUS-FNA had comparable efficacy and safety for the diagnosis of CCA. Brushing was the least sensitive diagnostic tool compared with intraductal biopsy or EUS-FNA. Given the modest diagnostic sensitivities of intraductal biopsy and EUS-FNA in the diagnosis of CCA, further studies for complementing these techniques with biomarkers may be needed.

Multidisciplinary Approach to Indeterminate Biliary Strictures

Biliary strictures that remain unclassified after cross-sectional imaging and endoscopic retrograde cholangiopancreatography-based tissue sampling are defined as indeterminate biliary strictures (IDBS). A substantial proportion of biliary strictures fall into this category due to low sensitivity of brush cytology and intraductal biopsy. Over last few decades, several modalities have emerged for the evaluation of IDBS. Of these, cholangioscopy and endosonography are the frontrunners and have cemented their place for the evaluation of IDBS. Both of these modalities are widely available, and therefore, biliary strictures that remain uncharacterized after their utilization represent IDBS in the current era.

Increasing the Yield: When More Is Better

Indeterminate biliary strictures pose a diagnostic challenge, and current approaches in the evaluation of such strictures lack diagnostic sensitivity. The most common method of tissue acquisition remains endoscopic retrograde cholangiopancreatography (ERCP) with brush cytology, however, little is known about optimal brush technique. In this paper by Wang et al., the authors compare the diagnostic sensitivity of brush cytology for 10, 20, and 30 passes in patients with malignant biliary strictures. The authors found an increase in sensitivity with an increasing number of passes, without an associated increase in adverse events. This well-designed study offers a simple and safe intervention which can increase the diagnostic sensitivity of ERCP-based brushing without requiring significant time, expense, or additional expertise.

Improving Diagnostic Yield in Indeterminate Biliary Strictures

Indeterminate biliary strictures are defined as a narrowing of the bile duct that cannot be differentiated as malignant or benign after performing cross-sectional imaging and an ERCP. Identifying the etiology of a bile duct stricture is the single most important step in determining whether a complex and potentially morbid surgical resection is warranted. Due to this diagnostic and therapeutic dilemma, new technologies, laboratory tests, and procedures are emerging to solve this problem.

Endoscopic Evaluation of Biliary Strictures: Current and Emerging Techniques

The diagnosis of biliary strictures in clinical practice can be challenging. Discriminating between benign and malignant biliary strictures is important to prevent the morbidity and mortality associated with incorrect diagnoses. Missing a malignant biliary stricture may delay surgery, resulting in poor prognostic outcomes. Conversely, it has been demonstrated that approximately 20% of patients who undergo surgery for suspected biliary malignancies have a benign etiology on histopathology. Traditional tissue sampling using endoscopic retrograde cholangiography does not always produce a definitive diagnosis, with a considerable proportion of cases remaining as indeterminate biliary strictures. Recent advances in endoscopic techniques have the potential to improve the diagnostic and prognostic accuracy of biliary strictures.

Optimal tissue sampling during ERCP and emerging molecular techniques for the differentiation of benign and malignant biliary strictures

Patients with cholangiocarcinoma have poor survival since the majority of patients are diagnosed at a stage precluding surgical resection, due to locally irresectable tumors and/or metastases. Optimization of diagnostic strategies, with a principal role for tissue diagnosis, is essential to detect cancers at an earlier stage amenable to curative treatment. Current barriers for a tissue diagnosis include both insufficient tissue sampling and a difficult cyto- or histopathological assessment. During endoscopic retrograde cholangiopancreatography, optimal brush sampling includes obtaining more than one brush within an individual patient to increase its diagnostic value. Currently, no significant increase of the diagnostic accuracy for the new cytology brush devices aiming to enhance the cellularity of brushings versus standard biliary brush devices has been demonstrated. Peroral cholangioscopy with bile duct biopsies appears to be a valuable tool in the diagnostic work-up of indeterminate biliary strictures, and may overcome current technical difficulties of fluoroscopic-guided biopsies. Over the past years, molecular techniques to detect chromosomal instability, mutations and methylation profiling of tumors have revolutionized, and implementation of these techniques on biliary tissue during diagnostic work-up of biliary strictures may be awaited in the near future. Fluorescence in situ hybridization has already been implemented in routine diagnostic evaluation of biliary strictures in several centers. Next-generation sequencing is promising for standard diagnostic care in biliary strictures, and recent studies have shown adequate detection of prevalent genomic alterations in KRAS, TP53, CDKN2A, SMAD4, PIK3CA, and GNAS on biliary brush material. Detection of DNA methylation of tumor suppressor genes and microRNAs may evolve over the coming years to a valuable diagnostic tool for cholangiocarcinoma. This review summarizes optimal strategies for biliary tissue sampling during endoscopic retrograde cholangiopancreatography and focuses on the evolving molecular techniques on biliary tissue to improve the differentiation of benign and malignant biliary strictures.

Aspiration fluid cytology during single operator cholangioscopy with targeted biopsy to improves the diagnostic yield in indeterminate biliary strictures

INTRODUCTION

Sensitivities of various sampling methods to detect malignant biliary strictures remain suboptimal. Irrigation during digital single operator cholangioscopy (dSOC) is done routinely for visualization of the duct. The aim of this study was to evaluate improvement of the sensitivity for detecting malignant biliary strictures when adding aspiration fluid cytology (AFC) from the irrigated fluid during cholangioscopy to cholangioscopic biopsy (CBx).

METHODS

We conducted a retrospective analysis of patients at a tertiary medical center who underwent CBx for evaluation of their biliary strictures. We included patients who had aspiration of fluid from the bile duct after CBx and were sent for cytology from January 2017 to October 2017. Diagnosis was made on the basis of final pathology or follow-up over 9 months.

RESULTS

Fifty-six patients had CBx obtained, out of which 35 patients had AFC in conjunction. Twenty-two (62%) patients were male and the average age was 65 years. Considering atypical cells as benign, the sensitivity, specificity, positive and negative predictive values (PPV, NPV) for CBx were 62.5%, 100%, 100%, and 76% respectively. When CBx combined with AFC, the above statistics went up to 81.25%, 100%, 100%, and 86.36% respectively. When atypical cells were considered malignant, the sensitivity, specificity, PPV and NPV for CBx were 81.25%, 84.21%, 81.25%, 84.21% and increased to 93.75%, 78.94%, 78.94%, and 93.75% respectively after adding AFC results.

CONCLUSION

For patients with biliary stricture, addition of AFC dSOC guided biopsies, significantly improves the sensitivity for detecting malignancy.

Endoscopic retrograde cholangiopancreatography guided interventions in the management of pancreatic cancer

Pancreatic cancer is the leading cause of cancer-related morbidity and mortality with an overall five-year survival of less than 9% in the United States. At presentation, the majority of patients have painless jaundice, pruritis, and malaise, a triad that develops secondary to obstruction, which often occurs late in the course of the disease process. The technical advancements in radiological imaging and endoscopic interventions have played a crucial role in the diagnosis, staging, and management of patients with pancreatic cancer. Endoscopic retrograde cholangiopancreatography (ERCP)-guided diagnosis (with brush cytology, serial pancreatic juice aspiration cytologic examination technique, or biliary biopsy) and therapeutic interventions such as pancreatobiliary decompression, intraductal and relief of gastric outlet obstruction play a pivotal role in the management of advanced pancreatic cancer and are increasingly used due to improved morbidity and complication rates compared to surgical management. In this review, we highlight various ERCP-guided diagnostic and therapeutic interventions for the management of pancreatic cancer.

Transpapillary tissue sampling of biliary strictures: balloon dilatation prior to forceps biopsy improves sensitivity and accuracy

The early and definitive diagnosis of malignant bile duct stenoses is essential for a timely and adequate therapy. However, tissue sampling with transpapillary brush cytology (BC) or forceps biopsy (FB) remains challenging. With this study, we aimed to compare the effectiveness and safety of different tissue sampling modalities (BC, FB without/after previous balloon dilatation). Standardized database research identified all patients, who underwent endoscopic retrograde cholangiography with BC and/or FB for indeterminate bile duct stenosis between January 2010 and April 2018 and with a definitive diagnosis. 218 patients were enrolled (149 cases with malignant and 69 with benign disease). FB had a significant higher sensitivity than BC (43% vs. 16%, p < 0.01). Prior balloon dilatation of the stenosis improved the sensitivity of FB from 41 to 71% (p = 0.03), the NPV from 36 to 81% (p < 0.01) and the accuracy from 55 to 87% (p < 0.01). The complication rates did not differ significantly between the modalities. In our center FB turned out to be the diagnostically more effective procedure. Balloon dilatation of the stenosis before FB had a significant diagnostic benefit and was not associated with a higher complication rate.

Approaches and Outcomes to Distal Cholangiocarcinoma

Distal cholangiocarcinoma is a rare malignancy with a dismal prognosis. Because of its location and aggressive nature, patients often present with locally advanced or metastatic disease, and effective treatment options are limited. For patients with resectable disease, surgery is the only chance for cure, but achieving an R0 resection is paramount. Optimal adjuvant therapy in resectable disease remains under investigation. Randomized controlled trials investigating neoadjuvant therapy and its impact on resectability and long-term outcomes are needed to continue to improve the outcomes of patients with distal cholangiocarcinoma.

Current Endoscopic Management of Malignant Biliary Stricture

Biliary and pancreatic cancers occur silently in the initial stage and become unresectable within a short time. When these diseases become symptomatic, biliary obstruction, either with or without infection, occurs frequently due to the anatomy associated with these cancers. The endoscopic management of these patients has changed, both with time and with improvements in medical devices. In this review, we present updated and integrated concepts for the endoscopic management of malignant biliary stricture. Endoscopic biliary drainage had been indicated in malignant biliary obstruction, but the concept of endoscopic management has changed with time. Although routine endoscopic stenting should not be performed in resectable malignant distal biliary obstruction (MDBO) patients, endoscopic biliary drainage is the treatment of choice for palliation in unresectable MDBO patients. Self-expanding metal stents (SEMS) have better stent patency and lower costs compared with plastic stents (PS). For malignant hilum obstruction, PS and uncovered SEMS yield similar short-term outcomes, while a covered stent is not usually used due to a potential unintentional obstruction of contralateral ducts.

Endoscopic Perspective in Cholangiocarcinoma Diagnostic Process

Cholangiocarcinoma is a malignancy arising from the epithelial lining of the intrahepatic or extrahepatic biliary tract. Timely diagnosis is challenging due to its silent clinical course. As reliable laboratory markers are lacking, diagnostic imaging plays a pivotal role. While cross-sectional imaging studies are usually conclusive for intrahepatic lesions, endoscopy plays an essential role in cases of extrahepatic tumors. Rational utilization of different diagnostic methods based on available evidence is needed. This article focuses on the diagnostic role of advanced biliary endoscopy, including endoscopic retrograde cholangiopancreatography, cholangioscopy, endoscopic ultrasonography, and intraductal sonography.

New Devices for Endoscopic Treatments in Gastroenterology: A Narrative Review

Endoscopy is in a period of continuous innovations in terms of image quality, endoscopes, post-processing software and lastly, application of Artificial Intelligence. Therapeutic boundaries have expanded, widening the grey zone between endoscopy and surgery, and increasing endoscopic approaches in clinical scenarios where, until a few years ago, surgery was the only option. New scopes and accessories have made it easier to access critical areas such as the biliary tree and the small bowel intestine. In the field of hepato-pancreato-biliary endoscopy (HPB), it is now possible to directly access the biliary ducts or cystic lesions though dedicated stents and scopes, rather than having to rely only on fluoroscopy and ultrasound, increasing the diagnostic and therapeutic options by applying a three-dimensional approach. This narrative review will give an overview of some of the most relevant emerging fields in luminal and HPB endoscopy, highlighting advantages and main limitations of the techniques, and providing considerations for future development.

Cholangiocarcinoma: a site-specific update on the current state of surgical management and multi-modality therapy

Biliary tract cancers (BTC) are rare, heterogeneous malignancies that include cholangiocarcinoma and gallbladder cancer (GBC). Cholangiocarcinoma subtypes differ by anatomic location and molecular profile. Currently, resection with lymphadenectomy is the only curative treatment of locally advanced cholangiocarcinoma. Given the high risk of recurrence, multi-modality therapy spanning surgery, chemotherapy, and radiation therapy should be considered. Current data is discordant and there is limited prospective data to support an optimal treatment regimen, though recent studies have demonstrated the utility of adjuvant chemotherapy and chemoradiation in specific settings and patient populations. There is a potential role for neoadjuvant chemotherapy in patients with resectable disease or chemoradiation in select patients with unresectable, locally advanced disease. Randomized clinical trials are necessary to establish the effectiveness of therapies specific to disease sites, especially with the emerging role of immunotherapy and targeted therapy to actionable mutations.

Practical Management of Indeterminate Biliary Strictures

Indeterminate biliary strictures pose a diagnostic and therapeutic challenge. Although underlying malignancy is a primary concern, biliary strictures may result from benign processes. An accurate diagnosis is paramount to define the treatment strategy and minimize morbidity. The limitations of traditional endoscopic retrograde cholangiopancreatography-based tissue acquisition with cytology brushings are well-documented. Endoscopic retrograde cholangiopancreatography is generally unable to determine a stricture's etiology. Complementary advanced endoscopic imaging and multimodal tissue acquisition have evolved. Careful consideration of the clinical presentation, location of the stricture, and interpretation of imaging constitute the most optimal approach for diagnosis and management.

Preoperative diagnosis of well-differentiated neuroendocrine tumor in common hepatic duct by brush cytology: A case report

The biological behavior of neuroendocrine tumors (NETs) is heterogeneous and differs from that of cholangiocarcinoma, which is the most common malignant tumor of the biliary tree. However, the preoperative diagnosis of NET in the biliary tree is extremely difficult and to our knowledge, diagnosis by brush cytology has not previously been reported. Herein, we first reported a case of biliary NET preoperatively diagnosed by brush cytology in a 33-year-old female patient. Imaging study revealed a 2.6-cm mass in the common hepatic duct. The brush cytology was characterized by loosely cohesive plasmacytoid tumor cells and scattered clusters of thin vascular septa. The tumor cells showed abundant cytoplasm and severe nuclear size variation but mitosis was not observed. Immunohistochemical staining of the cell block (CB) showed strong positivity for both synaptophysin and chromogranin A and a Ki-67 labeling index of 3.5%. The surgically resected bile duct mass was pathologically confirmed as NET, G2 with lymphovascular and perineural invasion of the tumor cells. The patient showed no evidence of tumor recurrence 10 months after operation without adjuvant chemotherapy. Suspicion of this rare tumor and immunohistochemical staining of the CB are important for the preoperative diagnosis of NET in the biliary tree.

Endoscopic retrograde cholangiopancreatography, lights and shadows: Handle with care

The role of endoscopic retrograde cholangiopancreatography (ERCP) has dramatically changed in the last years, mainly into that of a therapeutic procedure. The treatment of benign biliary disease, like “difficult” choledocolithiasis, with endoscopic papillary large balloon dilation combined with endoscopic sphinterotomy has proven an effective and safe technique. Moreover, safety in ERCP has improved as well, with the prevention of post-ERCP pancreatitis and patient-to-patient transmission of infections. The advent of self-expandable metal stenting has radically changed the management of biliopancreatic malignant strictures, while the role for therapy of benign strictures is still controversial. In addition, cholangioscopy (though the direct visualization of the biliopancreatic ductal system) has allowed for characterization of indeterminate biliary strictures and facilitated rescue therapy of large biliary stones deemed removable. Encouraging data from tissue ablation techniques, such as photodynamic therapy and radiofrequency ablation, need to be confirmed by large sample size clinical controlled trials. On the other hand, we have no drug-coated stents yet available to implant and evidence for the use of biodegradable stents is still weak. The competency and privileging of ERCP and endoscopic ultrasonography have been analyzed longer but the switch between the two procedures, at the same time, is becoming ordinary; as such, the endoscopist interested in this field should undergo parallel edification through training plans. Finally, the American Society for Gastrointestinal Endoscopy’s statement on non-anesthesiologist administration of propofol for gastrointestinal endoscopy is not actually endorsed by the European Society of Anaesthesiology, having many medical-legal implications in some European countries.

Investigation of Factors Affecting the Sensitivity of Bile Duct Brush Cytology

Objectives While bile duct brush cytology during endoscopic retrograde cholangiopancreatography (ERCP) is a well-established procedure for detecting malignant biliary stricture, its sensitivity is reportedly low. We aimed to determine the pre-ERCP factors affecting brush cytology sensitivity. Methods We retrospectively analyzed 185 patients who underwent brush cytology during the first ERCP for undiagnosed biliary stricture at our institution between January 2014 and December 2016. We analyzed the relationship of age, sex, final diagnosis, stricture location, tumor size, stricture length, total bilirubin level, white blood cell count, and C-reactive protein level with brush cytology sensitivity. Results The following conditions were established as final diagnoses: benign disease, 19 cases (10.3%); intrahepatic cholangiocarcinoma, 10 cases (5.4%); hilar cholangiocarcinoma, 38 cases (20.5%); extrahepatic cholangiocarcinoma, 44 cases (23.8%); pancreatic cancer, 55 cases (29.7%); other malignant tumors, 19 cases (10.3%). The sensitivity and specificity of brush cytology were 60.8% and 94.7%, respectively. The stricture length, total bilirubin level, and white blood cell count in true-positive cases were significantly higher than those in false-negative cases. Furthermore, a stratified analysis of the bilirubin levels demonstrated that sensitivity was highest in patients with moderate jaundice (80% for a total bilirubin level of 10-20 mg/dL), but significantly lower in patients with severe jaundice (total bilirubin level ≥20 mg/dL). Conclusion While the sensitivity of brush cytology increases with bilirubin levels of up to 20 mg/dL, severe jaundice has a negative effect on sensitivity, warranting additional pathological examinations according to the pre-ERCP bilirubin level.

[Cholangiocellular cancer: the state of the problem and ways to improve the results of surgical treatment]

AIM

To improve the outcomes in patients with resectable biliary cancer.

MATERIAL AND METHODS

There were 263 procedures for cholangiocellular carcinoma (CCC) for the period 1998—2017. Adjuvant chemotherapy was performed in 102 (38.8%) patients. Extensiveliver resections (78.9%) prevailed for intrahepatic cholangiocellular carcinoma (n=128), 6 (4.7%) patients required vascular resection. Seventy-seven pancreatoduodenectomies were performed for common bile duct cancer, portal vein resection was done in 8 (10.4%) patients. In case of Klatskin tumor (n=58) liver resection combined with bile duct resection (n=52) prevailed. Portal vein resection was done in 16 (27.6%) patients.

RESULTS

Postoperative morbidity in patients with intrahepatic CCC was revealed in 68 (53.1%) cases, mortality — in 5 (3.9%) cases. Among patients with Klatskin tumor morbidity was revealed in 51 (87.9%) cases, mortality — in 6 (10.3%) cases. In patients with common bile duct cancer morbidity was revealed in 53 (68.8%) cases, mortality — in 4 (5.2%) cases. In whole cohort median overall survival was 30 months. R0-resection was associated with better long-term results (median 37 months) compared with R1—R2 resection (20 months; p=0.01). Lymph node involvement is associated with significantly worse prognosis (p=0.016), however 5-year survival is observed (25.6%). Adjuvant chemotherapy in R0-resection significantly improved long-term results: median was 46 months (vs. 30 in group without chemotherapy; p=0.02). In intrahepatic CCC patients multiple lesions or mechanical jaundice did not aggravate long-term results.

CONCLUSION

R0-resection including lymphadenectomy, resection of adjacent organs and vessels is advisable for CCC. Isolated bile duct resection should be used as an exception. Adjuvant therapy improved long-term results. Multiple lymph node lesion or bile duct infiltration are not contraindications to surgery in intrahepatic CCC patients.

Review article: Asia-Pacific consensus recommendations on endoscopic tissue acquisition for biliary strictures

BACKGROUND

Pre-operative tissue diagnosis for suspected malignant biliary strictures remains challenging.

AIM

To develop evidence-based consensus statements on endoscopic tissue acquisition for biliary strictures.

METHODS

The initial draft of statements was prepared following a systematic literature review. A committee of 20 experts from Asia-Pacific region then reviewed, discussed, and modified the statements. Two rounds of independent voting were conducted to reach a final version. Consensus was considered to be achieved when 80% or more of voting members voted "agree completely" or "agree with some reservation."

RESULTS

Eleven statements achieved consensus. The choice of tissue sampling modalities for biliary strictures depends on the clinical setting, the location of lesion, and availability of expertise. Detailed radiological and endoscopic evaluation is useful to guide the selection of appropriate tissue acquisition technique. Standard intraductal biliary brushing and/or forceps biopsy is the first option when endoscopic biliary drainage is required with an overall (range) sensitivity and specificity of 45% (26%-72%) and 99% (98%-100%), and 48% (15%-100%) and 99% (97%-100%), respectively, in diagnosing malignant biliary strictures. Probe-based confocal laser endomicroscopy and fluorescence in situ hybridisation using 4 fluorescent-labelled probes targeting chromosomes 3, 7, 17 and 9p21 locus may be added to improve the diagnostic yield. Cholangioscopy-guided biopsy and EUS-guided tissue acquisition can be considered after prior negative conventional tissue sampling with an overall (range) sensitivity and specificity of 60% (38%-88%) and 98% (83%-100%), and 80% (46%-100%) and 97% (92%-100%), respectively, in diagnosing malignant biliary strictures.

CONCLUSION

These consensus statements provide evidence-based recommendations for endoscopic tissue acquisition of biliary strictures.

Modern work-up and extended resection in perihilar cholangiocarcinoma: the AMC experience

AIM

Perihilar cholangiocarcinoma (PHC) is a challenging disease and requires aggressive surgical treatment in order to achieve curation. The assessment and work-up of patients with presumed PHC is multidisciplinary, complex and requires extensive experience. The aim of this paper is to review current aspects of diagnosis, preoperative work-up and extended resection in patients with PHC from the perspective of our own institutional experience with this complex tumor.

METHODS

We provided a review of applied modalities in the diagnosis and work-up of PHC according to current literature. All patients with presumed PHC in our center between 2000 and 2016 were identified and described. The types of resection, surgical techniques and outcomes were analyzed.

RESULTS AND CONCLUSION

Upcoming diagnostic modalities such as Spyglass and combinations of serum biomarkers and molecular markers have potential to decrease the rate of misdiagnosis of benign, inflammatory disease. Assessment of liver function with hepatobiliary scintigraphy provides better information on the future remnant liver (FRL) than volume alone. The selective use of staging laparoscopy is advisable to avoid futile laparotomies. In patients requiring extended resection, selective preoperative biliary drainage is mandatory in cholangitis and when FRL is small (< 50%). Preoperative portal vein embolization (PVE) is used when FRL volume is less than 40% and optionally includes the left portal vein branches to segment 4. Associating liver partition and portal vein ligation for staged hepatectomy (ALPPS) as alternative to PVE is not recommended in PHC. N2 positive lymph nodes preclude long-term survival. The benefit of unconditional en bloc resection of the portal vein bifurcation is uncertain. Along these lines, an aggressive surgical approach encompassing extended liver resection including segment 1, regional lymphadenectomy and conditional portal venous resection translates into favorable long-term survival.

Agreement between endoscopic ultrasound-guided fine-needle aspiration and endobiliary brush cytology in suspected pancreaticobiliary malignancies

BACKGROUND AND STUDY AIMS

 For suspected pancreaticobiliary malignancies, endobiliary brush cytology during endoscopic retrograde cholangiopancreatography (ERCP) remains the diagnostic test of choice despite historically poor and variable sensitivity. This has led to increased use of endoscopic ultrasound-guided fine-needle aspiration (EUS-FNA) as an initial test. Recently, our institution began using a cytology brush that was designed specifically to collect a more substantial and higher-quality sample. The aim of this study was to investigate whether this brush design would provide more adequate samples and have high agreement with EUS-FNA in patients who underwent both procedures.

PATIENTS AND METHODS

 A retrospective chart review was conducted of all patients who underwent both EUS-FNA and endobiliary brush cytology for suspicion of pancreaticobiliary malignancy from January 2013 to May 2015. A total of 41 patients met the inclusion criteria. Initially, sample quality was evaluated. Final cytology results were then assessed for agreement with EUS-FNA using Cohen's kappa. The effect of considering atypical cytology as negative was also uniquely evaluated by running separate analyses.

RESULTS

 Brush cytology provided an adequate sample in 95.1 % of cases. Cohen's Kappa demonstrated moderate agreement between brush cytology and EUS-FNA: κ = 0.42 ( P  = 0.001). When atypical results were excluded, agreement increased: κ = 0.60 ( P  = 0.02), but remained moderate. If atypical results were considered "positive," the two procedures demonstrated equal cancer detection rates of 80.8 %.

CONCLUSIONS

 The studied brush provided more adequate samples compared with historical rates for brush cytology and had moderate agreement with EUS-FNA. If this brush truly increases sample adequacy, it could potentially provide results comparable to EUS-FNA at lower cost.

Proposal of a diagnostic algorithm for intraductal ultrasonography to distinguish between benign and malignant biliary strictures

To reexamine the recognizability of intraductal ultrasonography (IDUS) findings from an imaging database and propose a novel algorithm for clinical application. IDUS images of 102 patients who had undergone IDUS examinations for indeterminate causes of common bile duct dilation were independently reviewed by two endoscopists. The strength of the inter-rater agreement between the endoscopists was analyzed using Cohen's kappa (κ). An algorithm was implemented by arranging the IDUS characteristics according to their recognizability. The proposed algorithm was evaluated by examining the inter-rater agreement and diagnostic accuracy before and after the use of the algorithm. The strength of the inter-rater agreement was good for common bile duct stones with or without acoustic shadowing; intraluminal tumors; or bile duct wall thicknesses of more than or equal to 9 mm (κ > 0.8); followed by intraluminal hypoechoic nodules without common bile duct stone characteristics (κ = 0.771); and finally eccentric wall thickening, outer layer disruption, irregular mucosa, and destructed mural layers (κ: 0.595-0.419). Our algorithm improved the strength of inter-rater agreement with a diagnostic accuracy of 81.4%. We proposed an algorithm according to the recognizability of IDUS characteristics, and it can be used by endoscopists to evaluate such characteristics and determine the cause of biliary obstruction.

Mutation Profile and Fluorescence In Situ Hybridization Analyses Increase Detection of Malignancies in Biliary Strictures

BACKGROUND & AIMS

It is a challenge to detect malignancies in biliary strictures. Various sampling methods are available to increase diagnostic yield, but these require additional procedure time and expertise. We evaluated the combined accuracy of fluorescence in situ hybridization (FISH) and polymerase chain reaction-based DNA mutation profiling (MP) of specimens collected using standard brush techniques.

METHODS

We performed a prospective study of 107 consecutive patients treated for biliary strictures by endoscopic retrograde cholangiopancreatography from June 2012 through June 2014. We performed routine cytology and FISH analyses on cells collected by standard brush techniques, and analyzed supernatants for point mutations in KRAS and loss-of-heterozygosity mutations in tumor-suppressor genes at 10 loci (MP analysis was performed at Interpace Diagnostics). Strictures were determined to be nonmalignant based on repeat image analysis or laboratory test results 12 months after the procedure. Malignant strictures were identified based on subsequent biopsy or cytology analyses, pathology analyses of samples collected during surgery, or death from biliary malignancy. We determined the sensitivity and specificity with which FISH and MP analyses detected malignancies using the exact binomial test.

RESULTS

Our final analysis included 100 patients; 41% had biliary malignancies. Cytology analysis identified patients with malignancies with 32% sensitivity and 100% specificity. Addition of FISH or MP results to cytology results increased the sensitivity of detection to 51% (P < .01) without reducing specificity. The combination of cytology, MP, and FISH analyses detected malignancies with 73% sensitivity (P < .001). FISH identified an additional 9 of the 28 malignancies not detected by cytology analysis, and MP identified an additional 8 malignancies. FISH and MP together identified 17 of the 28 malignancies not detected by cytology analysis.

CONCLUSIONS

Addition of FISH and mutation analyses to cytology analysis significantly increased the level of sensitivity with which we detected malignancy in biliary strictures, with 100% specificity. These techniques can be performed using standard brush samples collected during endoscopic retrograde cholangiopancreatography, with mutations detected in free DNA in supernatant fluid of samples. The tests are complementary and therefore should be used sequentially in the diagnostic evaluation of biliary strictures.

Distinguishing Benign from Malignant Pancreatic and Periampullary Lesions Using Combined Use of ¹H-NMR Spectroscopy and Gas Chromatography-Mass Spectrometry

Previous work demonstrated that serum metabolomics can distinguish pancreatic cancer from benign disease. However, in the clinic, non-pancreatic periampullary cancers are difficult to distinguish from pancreatic cancer. Therefore, to test the clinical utility of this technology, we determined whether any pancreatic and periampullary adenocarcinoma could be distinguished from benign masses and biliary strictures. Sera from 157 patients with malignant and benign pancreatic and periampullary lesions were analyzed using proton nuclear magnetic resonance (¹H-NMR) spectroscopy and gas chromatography–mass spectrometry (GC-MS). Multivariate projection modeling using SIMCA-P+ software in training datasets (n = 80) was used to generate the best models to differentiate disease states. Models were validated in test datasets (n = 77). The final ¹H-NMR spectroscopy and GC-MS metabolomic profiles consisted of 14 and 18 compounds, with AUROC values of 0.74 (SE 0.06) and 0.62 (SE 0.08), respectively. The combination of ¹H-NMR spectroscopy and GC-MS metabolites did not substantially improve this performance (AUROC 0.66, SE 0.08). In patients with adenocarcinoma, glutamate levels were consistently higher, while glutamine and alanine levels were consistently lower. Pancreatic and periampullary adenocarcinomas can be distinguished from benign lesions. To further enhance the discriminatory power of metabolomics in this setting, it will be important to identify the metabolomic changes that characterize each of the subclasses of this heterogeneous group of cancers.

Performance of bile aspiration plus brushing to diagnose malignant biliary strictures during endoscopic retrograde cholangiopancreatography

BACKGROUND AND STUDY AIMS

Endobiliary brushing during endoscopic retrograde cholangiopancreatography (ERCP) is the main technique used to diagnose a malignant stricture, but has a poor sensitivity. This study evaluated the diagnostic performance of bile aspiration associated with biliary brushing during ERCP to diagnose a malignant stricture, compared to brushing alone.

PATIENTS AND METHODS

Between January 2007 and December 2012, all consecutive patients undergoing ERCP to treat a biliary stricture were included. After a biliary sphincterotomy, 3 mL to 10 mL of bile was aspirated into the brush catheter and collected in a dry sterile tube before and after brushing (to yield three samples). Brushing was performed as commonly recommended.

RESULTS

One hundred eleven patients (68 males, 43 females) were included; mean age 67 ± 15.4 years. A final diagnosis of malignant stricture was established in 51 patients, including 43 cholangiocarcinomas; 60 patients had benign strictures. Specificity (Sp) and positive predictive values were 100% for all samples. The diagnostic performance of the three-sample combination of bile aspiration + brushing + bile aspiration was significantly greater than brushing alone (P = 0.004): sensitivity (Se) = 84.3 % vs. Se = 66.7 %. The three-sample combination gave a negative predictive value of 88.2 %, and a diagnostic accuracy of 92.8 %. When suspicious results were added to malignant results as positive results, the three-sample combination gave Sp = 91.7 % and Se = 94.1 %.

CONCLUSIONS

In cases of biliary stricture, conducting bile aspiration before and after brushing significantly increased the ability to diagnose a malignant stricture with a sensitivity of 84.3 % (P = 0.004).

Serum albumin predicts survival in patients with hilar cholangiocarcinoma

BACKGROUND AND AIMS

Hilar cholangiocarcinoma is a devastating malignancy with incidence varying by geography and other risk factors. Rapid progression of disease and delays in diagnosis restrict the number of patients eligible for curative therapy. The objective of this study was to determine prognostic factors of overall survival in all patients presenting with hilar cholangiocarcinoma.

METHODS

All adult patients with histologically confirmed hilar cholangiocarcinoma from 2003 to 2013 were evaluated for predictors of survival using demographic factors, laboratory data, symptoms and radiological characteristics at presentation.

RESULTS

A total of 116 patients were identified to have pathological diagnosis of hilar cholangiocarcinoma and were included in the analysis. Patients with a serum albumin level >3.0 g/dL (P < 0.01), cancer antigen 19-9 ≤200 U/mL (P = 0.03), carcinoembryonic antigen ≤10 ìg/L (P < 0.01) or patients without a history of cirrhosis (P < 0.01) or diabetes (P = 0.02) were associated with a greater length of overall survival. A serum albumin level >3.0 g/dL was identified as an independent predictor of overall survival (hazard ratio 0.31; 95% confidence interval 0.14-0.70) with a survival benefit of 44 weeks.

CONCLUSION

This study was the largest analysis to date of prognostic factors in patients with hilar cholangiocarcinoma. A serum albumin level >3.0 g/dL conferred an independent survival advantage with a significantly greater length of survival.

Evaluation of Intraductal Ultrasonography, Endoscopic Brush Cytology and K-ras, P53 Gene Mutation in the Early Diagnosis of Malignant Bile Duct Stricture

Background:

In qualitative diagnosis of bile duct stenosis, single diagnostic measure is difficult to make a correct diagnosis, to combine several diagnostic techniques may be helpful to make an accurate diagnosis. The aim of this study was to evaluate the value of intraductal ultrasonography (IDUS), endoscopic brush cytology and K-ras, P53 gene mutation in the early diagnosis of malignant biliary stricture.

Methods:

From February 2012 to February 2013, 84 patients with suspected malignant biliary stricture were performed IDUS firstly, then endoscopic brush cytology and finally K-ras, P53 gene mutation detection, the sensitivity, specificity, positive predictive value, negative predictive value and accuracy of all above ways were evaluated and compared.

Results:

Of 84 patients, 52 cases were ultimately diagnosed malignant biliary stenosis; of which, 9 cases had no recurrence or metastasis to other organs after radical operation during the follow-up period. IDUS combined with brush cytology and K-ras + P53 gene mutation detection had obvious advantage in the sensitivity, accuracy and negative predictive value than any other joint detection and single detection (the advantage was more significant compared with IDUS + brush cytology or any single detection P < 0.01). There were obvious statistical significance in the sensitivity and accuracy between IDUS + brush cytology + P53 or IDUS + brush cytology + K-ras and IDUS + brush cytology or IDUS (P < 0.05). There was no statistical significance in the sensitivity, specificity, positive predictive value, negative predictive value and accuracy between IDUS + brush cytology + P53 and IDUS + brush cytology + K-ras (P > 0.05).

Conclusions:

IDUS combined with brush cytology and K-ras, P53 gene mutation detection is better than the separate detection and contribute to the early diagnosis of malignant biliary stricture. Its more widespread use is recommended.