Evolving role of endoscopic ultrasound in biliary stricture management: A meta-analysis and systematic review

Abstract

BACKGROUND

Endoscopic ultrasound (EUS) has evolved from a diagnostic tool to a management technique for various gastroenterological conditions, including biliary strictures.

AIM

To summarize the current evidence on EUS’s role in diagnosing and managing biliary strictures.

METHODS

Two independent reviewers searched five electronic databases (PubMed, CENTRAL, Science Direct, Google Scholar, and EMBASE) for articles published up to January 2025. Included articles met specific criteria, and statistical software was used to analyze reported outcomes.

RESULTS

Of 935 articles, 19 met the inclusion criteria. Ten articles focused on diagnostic EUS, while nine focused on EUS-guided therapeutic interventions. EUS fine-needle aspiration demonstrated superior sensitivity [0.43-1.00; 95% confidence interval (CI): 0.24-1.00] compared to conventional techniques (0.36-0.96; 95%CI: 0.19-0.99) for diagnosing malignant biliary strictures. Both EUS-fine-needle aspiration and conventional methods exhibited high specificity, with most achieving 100% specificity. EUS-guided interventions showed significantly higher clinical success rates than control interventions (odds ratio = 2.89; 95%CI: 1.22-6.84; P = 0.02). No significant difference was observed in technical success rates (odds ratio = 0.97; 95%CI: 0.30-3.16; P = 0.96).

CONCLUSION

EUS is a promising tool for diagnosing and managing biliary strictures. Combining EUS-guided and conventional interventions improves diagnostic performance. Further research is needed to investigate the feasibility and use of EUS-guided interventions in this field.

Key Words: Endoscopic ultrasound; Biliary strictures; Endoscopic ultrasound guided fine-needle aspiration; Systematic review; Clinical success rate

Core Tip: Endoscopic ultrasound (EUS) has emerged as a valuable tool for diagnosing and managing biliary strictures. This systematic review and meta-analysis found that EUS-guided fine-needle aspiration is superior to conventional techniques for diagnosing malignant biliary strictures, with higher sensitivity while maintaining high specificity. For management, EUS-guided interventions showed significantly higher clinical success rates compared to conventional methods, though technical success rates were similar. EUS-guided biliary drainage and stenting appear promising for cases where endoscopic retrograde cholangiopancreatography fails. However, more research is needed on the efficacy of various EUS-guided therapies for biliary strictures. Overall, EUS demonstrates an expanding and important role in biliary stricture diagnosis and treatment.

INTRODUCTION

Endoscopic ultrasound (EUS) is one of the most significant innovations in gastroenterology and related disciplines[1]. EUS has evolved as a critical tool for the diagnosis and management of various conditions[2]. Furthermore, its use has advanced to include the management of complications that may arise during endoscopic procedures. EUS has emerged as a pivotal tool for the diagnosis and management of various biliary pathologies[3].

Biliary strictures are areas of narrowing in both the intrahepatic and extrahepatic biliary systems. This condition results in biliary obstruction, which often leads to antegrade bile flow and pathological manifestations of the disease[4]. The clinical manifestations of biliary strictures are often variable depending on the severity of the disease and underlying pathologies. These manifestations include pruritus and jaundice, with other patients often being asymptomatic and strictures being diagnosed only on routine imaging studies[5].

Various tools are used to diagnose biliary strictures, of which the most common is magnetic resonance cholangiopancreatography (MRCP). It is the most sensitive non-invasive diagnostic tool for biliary pathologies, including biliary strictures[6]. However, EUS has emerged as an alternative and potential choice for diagnosing and managing biliary strictures[7]. In this article, we aimed to summarize the current evidence regarding the utility of EUS in both the diagnosis and management of biliary strictures. EUS is an advanced imaging technique combining endoscopy with high-frequency ultrasound, providing detailed visualization of the gastrointestinal tract and adjacent structures. It involves inserting a flexible endoscope with an ultrasound transducer into the gastrointestinal tract, allowing close proximity imaging of organs like the pancreas and biliary system. EUS offers advantages for biliary strictures, including high-resolution imaging, tissue sampling capability through EUS-guided fine needle aspiration or biopsy, and interventional applications. Compared to MRCP, EUS is minimally invasive, allows direct tissue sampling, provides real-time imaging, and typically offers higher spatial resolution. However, EUS is more operator-dependent and less widely available than MRCP. While MRCP remains the initial non-invasive imaging modality for suspected biliary strictures, EUS has emerged as a valuable complementary tool, particularly for tissue acquisition and detailed characterization of strictures.

MATERIALS AND METHODS

Protocol and registration

This systematic review was conducted according to the PRISMA 2020 guidelines[8]. The protocol for this review was not registered in any database.

Literature search

A literature search was conducted independently by two reviewers using two approaches. The reviewers defined a comprehensive search criterion for the electronic databases using the first approach. This criterion and the associated keywords were then used for the electronic search of five electronic databases: ScienceDirect, PubMed, Google Scholar, CENTRAL, and EMBASE. The keywords used for the electronic search included (Biliary strictures OR Malignant biliary strictures OR Benign biliary strictures OR Biliary obstruction) AND (Diagnosis) AND (Management) AND (EUS OR Ultrasound AND Endoscopic ultrasound-guided management). These keywords were then modified for each database to maximize the number of results obtained. After the electronic search, the reviewers reviewed the lists of references of the obtained studies to identify additional studies that would have likely been missed in the initial search. Lastly, the reviewers searched for any trials registered in the clinical trial.gov registry for any completed trial with results but lacking available publications.

Eligibility criteria

Once all the articles had been obtained from the databases and registries, the authors utilized the pre specified eligibility criteria to analyze each of the articles before their inclusion in the review.

The included articles were selected based on the following criteria: (1) Studies published in English; (2) Studies that included patients with both benign and malignant biliary strictures; (3) Studies investigating the use of EUS as a diagnostic tool for biliary strictures; (4) Studies investigating various EUS-guided interventions for biliary strictures; and (5) Studies designed as primary interventional studies, such as clinical trials.

Studies were excluded from the review during the eligibility analysis if they met the following criteria: (1) Studies that did not include patients with biliary strictures; (2) Studies that did not include EUS as a diagnostic tool or guide for various interventions; and (3) Secondary studies, including systematic reviews, meta-analyses, and narrative reviews.

Data extraction

Two independent reviewers conducted the study selection process in different phases. The phases entailed the removal of duplicate articles, screening abstracts and titles, and screening the available full texts. For inclusion in the review, the independent authors first screened the abstracts of articles obtained after removing duplicates. Articles that met the inclusion criteria were included in the study; however, if the reviewers could not ascertain their eligibility, they obtained the full text for screening. After completing the study selection process, the reviewers extracted all data and converted them into pilot-tested forms. The information extracted from each study included the study ID, study design, study setting, sample size, intervention, mean age of patients, inclusion criteria, and reported outcomes.

Quality assessment

Owing to the diverse designs of the included studies, we utilized various risk of bias (RoB) and methodological assessment tools to determine the RoB and methodological quality of the included studies. We used the RoB 2 tool provided by the Cochrane Collaboration for randomized controlled trials. For the diagnostic test accuracy (DTA) studies, we used the QUADAS2 to assess their methodological quality. Finally, we utilized the Newcastle-Ottawa scale for cohort and case-control studies to assess their methodological quality.

Statistical analyses

We used Review Manager Software (RevMan 5.4, The Cochrane Collaboration 2019, The Nordic Cochrane Centre, Copenhagen, Denmark) for quantitative synthesis. DTA meta-analysis was conducted for DTA studies. To facilitate the analysis, we used the data reported in the studies to calculate true positives, true negatives, false positives, and false negatives. To calculate these values from the summarized values provided in the studies, we utilized a web-based calculator provided by “2-way Contingency Table Analysis” (accessed at https://statpages.info/ctab2x2.html). These values were used to estimate the sensitivity and specificity of each diagnostic method. For interventional studies, we used the odds ratio (OR) to analyze the clinical and technical success rates as they were all dichotomous outcomes. We also used the I² to measure and quantify the heterogeneity of the studies.

RESULTS

Search outcomes

Our electronic search retrieved 935 articles from the databases. Duplication assessment helped remove 686 duplicates. The remaining 249 publications were assessed based on their title and abstract relevance, leading to the removal of 177 irrelevant studies. Seventy-two articles were then retrieved and evaluated based on our eligibility criteria. Finally, 19 articles that met the inclusion criteria were selected. The remaining articles were excluded for the following reasons: 8 published in language other than English, 7 other secondary studies, 12 did not report any of the required outcomes, 9 did not include patients with biliary strictures, and 17 did not include any EUS-guided interventions for either the management or diagnosis of biliary strictures. The PRISMA diagram in Figure 1 presents a detailed summary of the search strategy.

Figure 1 PRISMA diagram summarizing the search strategy. EUS: Endoscopic ultrasound.

Characteristics of the included studies

The review included 19 studies, of which 10 were DTA studies[9-18], and 9 were interventional studies[19-27]. Of the nine interventional studies, seven investigated biliary drainage after biliary obstruction secondary to biliary strictures, and two investigated the feasibility of using EUS-guided biliary stenting to manage biliary strictures. The characteristics of the included DTA studies are summarized in Table 1, and those of the included interventional studies are summarized in Table 2.

Table 1 Characteristics of included diagnostic test accuracy studies.

Ref.	Study design	Location of lesion	Sample size	Inclusion criteria	Diagnostic intervention	Gold standard	Findings	Center type
Novis et al, 2010[9]	Comparative study	Distal	46	Biliary obstruction	EUS-FNA and ERCP	Histology, surgery, and follow-up	Benign lesions (n = 7) and malignant lesions (n = 37)	SC
Fritscher-Ravens et al, 2004[10]	Prospective	Proximal	44	Patients with obstructive jaundice and a clinical suspicion of cancer	EUS-FNA	Autopsy, surgery, or follow-up	Benign (n = 12) and malignant (n = 31)	SC
Ohshima et al, 2011[11]	Prospective	Biliary	22	Patients with suspected malignant biliary strictures	EUS-FNA	Histology, surgery, and follow-up	Malignant (n = 16) and benign (n = 6)	SC
Weilert et al, 2014[12]	Prospective	Biliary	51	Patients with suspected pancreaticobiliary pathologies	EUS-FNA and ERCP	Surgery, definitive findings, and follow-up	Benign (n = 3) and malignant (n = 48)	SC
DeWitt et al, 2006[13]	Prospective	Proximal	24	Patients with suspected or confirmed proximal biliary strictures	EUS-FNA	Surgical pathology findings and follow-up	Malignant (n = 17) and benign (n = 7)	SC
Eloubeidi et al, 2004[17]	Prospective	Biliary	25	Patients with common bile duct strictures	EUS-FNA	Follow-up and surgical pathology	Malignant (n = 31) and benign (n = 7)	SC
Rösch et al, 2004[14]	Prospective	Biliary	50	Patients with indeterminate biliary strictures	EUS-FNA and ERCP	Follow-up and surgical pathology or other biopsy results	Malignant (n = 28) and benign (n = 22)	SC
Lee et al, 2019[15]	Prospective	Distal	181	Patients with suspected malignant biliary strictures	EUS-FNA, ERCP, and POC-FB	Surgical pathology findings and malignant diagnosis after biopsy or during follow-up	Malignant (n = 51) and benign (n = 8)	MC
Yeo et al, 2019[16]	Retrospective	Biliary	93	Patients with suspected biliary strictures	EUS-TS and ERCP-TS	Histopathology findings based on the surgical specimen, cytology findings of either EUS-TS or ERCP-TS, or during clinical follow-up	Malignant (n = 70) and benign (n = 16)	MC
Lee et al, 2017[18]	Prospective	Biliary	178	Patients with suspected malignant biliary strictures	ERCP with TPB and EUS-FNA	Histopathologic findings of the surgical specimens, diagnosis based on TPB or EUS-FNAB, or during the clinical imaging on follow-up	Malignant (n = 171) and benign (n = 7)	MC

EUS: Endoscopic ultrasound; FNA: Fine-needle aspiration; CI: Confidence interval; ERCP: Endoscopic retrograde cholangiopancreatography; SC: Surgical control; POC-FB: Peroral cholangioscopy with forceps biopsy; TS: Technical success; TPB: Transpapillary biopsy; FNAB: Fine needle aspiration biopsy; MC: Multi-center.

Table 2 Characteristics of the included interventional studies.

Ref.	Study design	Study setting	Study group	Sample size	Mean age (years)	Inclusion criteria	Reported outcomes	Center type
Bang et al, 2018[19]	RCT	United States	EUS-BD	33	69.4 ± 12.6	Patients with obstructive jaundice and a pancreatic head mass	Rate of adverse events, technical success, treatment success, re-interventions, and procedural duration	MC
Paik et al, 2018[20]	RCT	South Korea	EUS-BD	64	64.8	Adult patients with unresectable malignant biliary strictures	Technical success rates, clinical success rates, median hospital stay, and early adverse events	MC
Sharaiha et al, 2016[21]	Retrospective case-control study	United States	EUS-BD	47	-	Patients with either malignant or benign biliary obstruction	Technical and clinical success, post-procedural pain, and incidence of adverse events	SC
Bapaye et al, 2013[22]	Retrospective case-control study	India	EUS-BD	25	59.9 ± 13.3	Patients with unresectable malignancies causing biliary obstruction	Successful stent placement and incidence of complications	SC
Huang et al, 2017[23]	Retrospective case-control study	China	EUS-BD	36	68 ± 4.62	Patients with failed ERCP for the management of obstructive jaundice secondary to malignancy	Technical and clinical success rates, complications, and length of hospital stay	SC
Lee et al, 2016[24]	RCT	South Korea	EUS-BDS	34	66.5	Patients with distal MBOs	Technical and functional success, procedure-related adverse events, reintervention rate, and hospital stay	MC
Khashab et al, 2015[25]	Retrospective case-control study	UnitedStates	EGBD	64	64.9 ± 12.5	Patients with distal MBOs with at least one failed ERCP session	Adverse events, procedure-related costs, and reintervention rates	SC
Artifon et al, 2012[26]	RCT	Brazil	EUS-CD	13	63.4 ± 11.1	Patients with unresectable MBOs	Success rate, quality of life outcomes, and incidence of adverse events	SC
Bill et al, 2016[27]	Retrospective case–control study	United States	EUSr	25	65.4 ± 11.6	Patients with MDBO with a previous failed ERCP	Technical and clinical success, length of hospital stay, and repeat procedure rate	SC

RCT: Randomized controlled trial; EUS-BD: Endoscopic ultrasound-biliary drainage; MC: Multi-center ; SC: Surgical control; EUS-BDS: Endoscopic ultrasound-biliary drainages; EGBD: Endoscopy guided biliary drainage; EUS-CD: Endoscopic ultrasound-guided choledochoduodenostomy; MBOs: Malignant biliary obstructions; MDBO: Malignant distal biliary obstruction; ERCP: Endoscopic retrograde cholangiopancreatography.

Methodological quality and RoB of the included studies

Most of the included DTA studies had good methodological quality with a low RoB (Figure 2). In the study by Yeo et al[16], there were some concerns due to a lack of blinding and the absence of a registered protocol. All cohort and case-control studies had good Agency for Healthcare Research and Quality standards for methodological quality. The studies were noted as having a good methodology for the selection of participants and reporting of outcomes (Table 3). Of the five randomized controlled trials, only one had a low RoB[20]. The remainder had “some concerns” attributed to bias in deviations from the intended intervention and selection of the reported results (Figure 2B)[19,24-26].

Figure 2 Methodological quality and risk of bias of the included studies. A: Summary graph of the methodological quality of the included diagnostic test accuracy studies; B: Risk of bias graph of the included randomized controlled trials.

Table 3 The Newcastle-Ottawa scale summarizes the methodological quality of the cohort and case-control studies.

Ref.	Selection	Comparability	Reporting	AHRQ standard
Khashab et al, 2015[25]	3	1	3	Good
Sharaiha et al, 2016[21]	3	2	3	Good
Bapaye et al, 2013[22]	3	1	3	Good
Huang et al, 2017[23]	3	2	3	Good
Bill et al, 2016[27]	3	1	3	Good

AHRQ: Agency for Healthcare Research and Quality.

Meta-analysis results

Diagnostic accuracy of EUS-fine-needle aspiration for malignant biliary strictures: The meta-analysis was performed separately for DTA and interventional studies. Meta-analysis showed that the sensitivity of EUS-fine-needle aspiration (FNA) in the diagnosis of malignant biliary strictures ranged from 0.43 [95% confidence interval (CI): 0.24-0.63] to 1.00 (95%CI: 0.79-1.00), with a very high specificity of 1.00 (95%CI: 0.16-1.00) (Figure 3). In contrast, the conventional diagnostic methods had a sensitivity ranging from 0.36 (95%CI: 0.19-0.56) to 0.96 (95%CI: 0.90-0.99). These methods also had high specificity for the detection of malignant biliary strictures, with specificity ranging from 0.89 (95%CI: 0.89) (95%CI: 0.52-1.00) to 1.00 (95%CI: 0.85-1.00) (Figure 3). To further elucidate the results, we generated standardized receiver operating curves for the two diagnostic methods. While RevMan 5.4 did not allow us to generate the value of the area under the curve for each diagnostic method, a visual inspection of the curve indicated that the area under the curve of EUS-FNA was greater than that of conventional methods (Figure 4). Thus, we concluded that EUS-FNA has superior diagnostic efficacy.

Figure 3 Forest plot showing the diagnostic accuracy of endoscopic ultrasound fine-needle aspiration compared with conventional methods. EUS: Endoscopic ultrasound; FNA: Fine-needle aspiration; CI: Confidence interval; TP: True positives; FP: False positives; FN: False negatives; TN: True negatives.

Figure 4 Standardized receiver operating curves curve showing the comparative diagnostic accuracy of endoscopic ultrasound and conventional diagnostic methods. EUS: Endoscopic ultrasound; FNA: Fine-needle aspiration; CI: Confidence interval.

Efficacy of EUS-guided therapies for biliary strictures: We analyzed the efficacy of two EUS-guided therapies for managing biliary strictures: EUS-guided biliary drainage and EUS-guided biliary stent placement.

Technical success rate: Technical success rates were reported in nine studies. We pooled the reported results and found no significant difference in the technical success rate of EUS-guided procedures and conventional methods (OR = 0.97; 95%CI: 0.30-3.16; P = 0.96) (Figure 5A). In the included studies, two interventions were investigated; therefore, we conducted a subgroup analysis to determine the comparative efficacy of each intervention. Similarly, the technical success rates of EUS-guided biliary drainage and EUS-guided biliary stent placement were comparable to those of conventional interventions (OR = 0.65; 95%CI: 0.18-2.29; P = 0.50) and (OR = 2.99; 95%CI: 0.15-60.58; P = 0.48), respectively (Figure 5A).

Figure 5 Forest plot. A: Forest plot showing the technical success rate of endoscopic ultrasound-guided interventions compared to conventional methods for managing biliary strictures; B: Forest plot showing the clinical success rate of endoscopic ultrasound-guided procedures compared to conventional methods. EUS: Endoscopic ultrasound; CI: Confidence interval.

The distinction between technical and clinical success rates in EUS-guided interventions is critical, with technical success referring to the successful completion of the procedure itself, while clinical success relates to the achievement of the desired clinical outcome or symptom resolution. Limitations due to heterogeneity include patient population variability, different control interventions, sample size limitations, study design variability, and subgroup analysis limitations. The inclusion of both malignant and benign biliary strictures introduces variability affecting result interpretation and generalizability. Different comparators complicate the assessment of comparative effectiveness, while limited studies for some interventions potentially affect conclusion reliability. Differences across included studies contribute to heterogeneity, and the inability to conduct detailed subgroup analyses due to heterogeneity limits insights into various factors' impact on outcomes. These limitations should be acknowledged as they affect the strength and generalizability of conclusions.

Clinical success rate: The clinical success rate was reported in eight of the included studies. A pooled analysis of these results showed that the clinical success rate of EUS-guided procedures was significantly higher than that of conventional methods (OR = 2.89; 95%CI: 1.22-6.84; P = 0.02) (Figure 5B). Similarly, when we conducted a subgroup analysis, we found that the clinical success rate of EUS-guided biliary stent placement was significantly higher than that of endoscopic retrograde cholangiopancreatography-guided stent placement (OR = 8.18; 95%CI: 2.10-31.83; P = 0.002). However, the clinical success rate of EUS-guided biliary drainage was comparable to that of ERCP-guided biliary drainage (OR = 2.14; 95%CI: 0.83-5.49; P = 0.11) (Figure 5B).

DISCUSSION

Our results show that EUS-FNA is superior to other diagnostic methods for malignant biliary strictures. In addition, EUS-guided interventions have inconsistent efficacy in managing biliary strictures compared with conventional diagnostic methods. Although the clinical success of EUS-guided procedures is significantly higher than that of conventional diagnostic methods, the technical success rate is still comparable.

Utility of EUS in the diagnosis of biliary strictures

While EUS has shown promising results in the diagnosis of biliary strictures, the current diagnostic approach does not focus solely on one diagnostic method. Instead, most clinicians advocate a multimodal approach for diagnosing most biliary strictures[28,29]. Notably, in most of the studies included in this review, EUS-FNA was considered after an initial diagnosis of ERCP, which yielded negative results. This indicates that ERCP plays a crucial role in diagnosing malignant biliary strictures in the general population. However, owing to the low sensitivity of ERCP, clinicians are considering EUS-FNA to mitigate the limitations of ERCP. Furthermore, in some studies, combining ERCP with EUS has significantly increased the sensitivity and specificity of the combined approach[9].

Our study found that EUS-FNA had superior diagnostic efficacy compared with conventional diagnostic methods. Similar to our findings, a previous review by De Moura et al[30] found that EUS was superior to ERCP in the diagnosis of malignant biliary strictures. Another review reported similar results and highlighted the utility of EUS-FNA in diagnosing distal malignant biliary strictures[31]. While our review did not stratify our outcomes according to the anatomic location of the lesion, previous studies have highlighted EUS-FNA as a promising tool with positive results in the diagnosis of distal malignant biliary strictures[32]. However, more research should be conducted to determine if the anatomic location of the biliary stricture affects the diagnostic performance of EUS-FNA. It is imperative to note that both EUS-FNA and conventional methods, such as ERCP, have high specificity for malignant biliary strictures.

EUS-guided therapies for biliary strictures

The current guidelines of the American Society of Gastrointestinal Endoscopy recommend ERCP as the initial intervention for patients with biliary strictures after liver transplantation[33]. However, the European Society of Gastrointestinal Endoscopy discourages routine biliary drainage in patients with biliary obstruction and instead recommends the placement of self-expandable metal stents for preoperative and palliative extrahepatic biliary obstruction[34]. The placement of these stents was mainly performed under ERCP guidance. However, when ERCP-guided stenting fails, EUS-guided drainage is preferred to percutaneous drainage[35]. Our review found no significant difference in the technical success of EUS-guided drainage after failed ERCP and transhepatic biliary drainage.

Our study also found that EUS-guided biliary stent placement was a promising and feasible method for managing biliary strictures. While we only summarized data from two studies, our findings indicate that EUS-guided biliary stenting exhibited a better clinical success rate than control interventions. However, as our review is based on a limited number of studies, further research is required to generate more empirical evidence on the utility of EUS-guided biliary stenting in managing biliary strictures.

Limitations of the study

In the current review, we employed a robust methodological approach to summarize the current evidence regarding the role of EUS in the diagnosis and management of biliary strictures. However, this review has some limitations. First, the study population was heterogeneous. The sample population included patients with malignant or other biliary strictures. The generalizability of the results may be limited because of the diversity in the patient population. Second, in the DTA meta-analysis, we could only determine the comparative diagnostic accuracy of EUS-FNA in the diagnosis of malignant biliary strictures. While malignant biliary strictures are of clinical significance due to their prognostic implications for the patient population, it is also essential to determine the accuracy of EUS-FNA in diagnosing other types of biliary strictures. Furthermore, we could only analyze the efficacy of EUS-guided biliary drainage and stent placement. However, only two of the included studies investigated the effectiveness of EUS-guided biliary stent placement. Therefore, this factor limits the sample size from which we draw our conclusions and findings. Lastly, the control interventions varied, including ERCP and percutaneous transhepatic biliary drainage, thereby affecting the outcome of our analysis. However, we could not conduct further subgroup analyses to determine whether different types of control interventions affected the comparative effectiveness of EUS-FNA. Here is a paragraph explicitly stating limitations due to heterogeneity in this article.

Other important limitations due to heterogeneity across the included studies. The study population was heterogeneous, including patients with both malignant and benign biliary strictures. This diversity in the patient population may limit the generalizability of the results. Additionally, there was heterogeneity in the control interventions used across studies, including both ERCP and percutaneous transhepatic biliary drainage. This variability in comparator interventions affects the interpretation of the comparative effectiveness analyses. Furthermore, only a limited number of studies were available for some interventions, such as EUS-guided biliary stent placement, restricting the sample size for drawing conclusions about those specific techniques. The heterogeneity in study designs, patient populations, interventions, and comparators precluded more detailed subgroup analyses that could have elucidated the impact of these factors on outcomes. Overall, the heterogeneity across studies limits the strength of conclusions that can be drawn, particularly regarding specific EUS-guided therapies for managing biliary strictures.

The article acknowledges potential publication bias as a limitation in the systematic review of EUS in managing biliary strictures. This bias may arise from the tendency to publish positive or significant results more frequently than negative or inconclusive findings, leading to an overrepresentation of favorable outcomes in the literature. The review's reliance on published studies could skew the perceived efficacy of EUS-guided interventions, as studies with less favorable results might remain unpublished or underreported. Consequently, this could affect the overall conclusions drawn regarding the effectiveness of EUS in diagnosing and managing biliary strictures, highlighting the need for more comprehensive research that includes unpublished data to provide a balanced perspective on the topic.

CONCLUSION

Our study results show that EUS-FNA is superior to ERCP and other conventional diagnostic modalities for the diagnosis of malignant biliary strictures. Furthermore, EUS-guided therapies have shown promising results in the management of biliary strictures. However, the current evidence of their superior efficacy is inconsistent and is based on a limited number of studies. Therefore, we recommend that further studies should be conducted to determine the feasibility and effectiveness of a wider range of EUS-guided therapies for managing biliary strictures.