
==== Front
BMC Gastroenterol
BMC Gastroenterol
BMC Gastroenterology
1471-230X
BioMed Central London

39261769
3406
10.1186/s12876-024-03406-5
Research
Diagnostic yield of endoscopic ultrasound in dilated common bile duct with non-diagnostic cross-sectional imaging
Mahajan Ankit 1
Das Kshaunish 1
Kishalaya 1
Misra Debashis debcnmch@yahoo.com

1
Das Kausik 2
Dhali Gopal Krishna 1
1 grid.414764.4 0000 0004 0507 4308 Department of Gastroenterology, School of Digestive and Liver Diseases, Institute of PostGraduate Medical Education & Research, 244, A.J.C. Bose Road, Kolkata, West Bengal PIN 700020 India
2 grid.414764.4 0000 0004 0507 4308 Department of Hepatology, School of Digestive and Liver Diseases, Institute of PostGraduate Medical Education & Research, 244, A.J.C. Bose Road, Kolkata, West Bengal PIN 700020 India
12 9 2024
12 9 2024
2024
24 30918 5 2024
5 9 2024
© The Author(s) 2024
2024
https://creativecommons.org/licenses/by-nc-nd/4.0/ Open Access This article is licensed under a Creative Commons Attribution-NonCommercial-NoDerivatives 4.0 International License, which permits any non-commercial use, sharing, distribution and reproduction in any medium or format, as long as you give appropriate credit to the original author(s) and the source, provide a link to the Creative Commons licence, and indicate if you modified the licensed material. You do not have permission under this licence to share adapted material derived from this article or parts of it. The images or other third party material in this article are included in the article’s Creative Commons licence, unless indicated otherwise in a credit line to the material. If material is not included in the article’s Creative Commons licence and your intended use is not permitted by statutory regulation or exceeds the permitted use, you will need to obtain permission directly from the copyright holder. To view a copy of this licence, visit http://creativecommons.org/licenses/by-nc-nd/4.0/.
Background

Biliary dilatation without obvious etiology on cross sectional imaging warrants further investigation. This study aimed to assess yield of endoscopic ultrasound in providing etiologic diagnosis in such situation.

Methods

Prospective cohort of consecutive patients with biliary dilatation & non diagnostic computed tomography (CT) and /or magnetic resonance imaging (MRI) underwent endoscopic ultrasound (EUS) with/without fine needle aspiration cytology (FNAC) and were followed clinically, biochemically with/without radiology for up to six months. The findings of EUS were corroborated with histopathology of surgical specimens and endoscopic retrograde cholangiography (ERCP) findings in relevant cases.

Results

Median age of 121 patients completing follow up was 55 years. 98.2% patients were symptomatic and median common bile duct (CBD) diameter was 13 mm. EUS was able to identify lesions attributable for biliary dilatation in (67 out of 121) 55.4% cases with ampullary neoplasm being the commonest (29 out of 67 i.e. 43%). Multivariate logistic regression analysis identified jaundice as the predictor of positive diagnosis on EUS, of finding ampullary lesion and pancreatic lesion on EUS. EUS had sensitivity, specificity, positive predictive value and diagnostic accuracy of 95.65%, 94.23%, 95.65% and 95.04% respectively in providing etiologic diagnosis. Threshold value for baseline bilirubin of 10 mg%, for baseline CA 19.9 of 225 u/L and for largest CBD diameter of 16 mm were determined to have specificity of 98%, 95%, 92.5% respectively of finding a positive diagnosis on EUS.

Conclusion

EUS provides considerable diagnostic yield with high accuracy in biliary dilatation when cross sectional imaging fails to provide etiologic diagnosis.

Keywords

Common bile duct
Computed tomography
Choledochal cyst
Choledocholithiasis
Endosonography
Jaundice
Logistic models
Magnetic resonance cholangiopancreatography
Pancreatic neoplasms
Prospective studies
issue-copyright-statement© BioMed Central Ltd., part of Springer Nature 2024
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pmcIntroduction

Dilated common bile duct (CBD) with or without symptoms is a situation that is encountered by gastroenterologists in their daily practice. Magnetic resonance imaging (MRI) or computed tomography (CT) scan is usually employed for etiological evaluation of biliary obstruction after detection of dilated biliary tree on transabdominal ultrasound (USG). However, USG, CT and MRI all have their limitations in identifying the etiology of biliary obstruction. Transabdominal ultrasound has wide range of sensitivity in determining level (27 to 95%) and etiology (23 to 81%) of obstruction [1, 2]. The accuracy of CT scan in identifying the level of and etiology of obstruction is close to 90% [3, 4]. Magnetic resonance cholangiopancreatography (MRCP) also has high sensitivity and specificity for detection of benign and neoplastic biliary obstruction [5]. However, in 5 to 10% of cases the etiology of obstruction eludes CT & MRCP [3–5]. Endosonography or endoscopic ultrasound (EUS) is a helpful modality in this scenario to detect lesions producing biliary obstruction specially those located in the periampullary region [6, 7]. We undertook this single centre prospective observational study to assess the role of EUS in detecting lesions producing biliary obstructions when cross sectional imaging such as CT or MRI is unable to detect the same.

Methods

Patients

One hundred forty-one consecutive patients attending Gastroenterology outpatient department (OPD) or admitted in Gastroenterology department of Institute of Post Graduate Medical Education & Research, Kolkata with dilated common bile duct as initially detected by USG and subsequently evaluated with MRI (1.5 Tesla or higher) or CT scan (16 slices or higher) or both but without etiological diagnosis, were planned to undergo EUS. Most of the patients were referred from different centres for evaluation in our tertiary referral centre with CT scan and/or MRCP. CT scans were of 16 slices or higher and MRI were of 1.5 Tesla or higher. Clinical history, biochemical profile such as liver function test (LFT), carbohydrate antigen (CA 19.9) and radiology work up (USG, CT, MRI) were recorded at baseline. Study enrolment was conducted from August 2020 to June 2021.

Inclusions criteria: Patients referred for evaluation of biliary ductal dilatation (defined as CBD diameter > 6 mm on USG [8, 9], > 8 mm on CT abdomen [10] and > 6 mm on MRCP, in those with GB in-situ); and > 10 mm in post-cholecystectomy patients [11] with no definite etiology of CBD dilatation on cross sectional imaging.

Exclusion criteria: a) The patients who are not willing to give written consent b) patient with altered anatomy due to previous surgery c) pregnant females d) patients with age less than 18 years e) unfit for sedation required for EUS examination.

Study protocol

EUS

EUS was performed in 139 patients after getting proper consent. EUS examinations were performed by two gastroenterologists with experience of more than 1000 EUS procedures. All EUS procedures were performed by “Pentax” linear echoendoscope with patients in left lateral position. It was performed under conscious sedation using intravenous medications such as midazolam and propofol. In appropriate situation fine needle aspiration cytology (FNAC) was also done. After the procedure was done, all the patients were kept in day care for next four hours & were discharged on the same day. EUS examination could not be completed in two patients due to gastric outlet obstruction.

CT scan

Patients were kept nothing per oral for 4 h before the procedure and were asked to drink 1 L water within 30 min before CT images were taken. 1.5 ml /kg body weight of intravenous contrast (iohexol) was administered. 1.5 mm slice thickness with no interslice gap was used with multiplanar reconstruction (axial, coronal and sagittal planes).

MRI

Patients were kept nothing per oral for 4 h before the procedure. Heavily T2 weighted images with reconstructed MRCP view, 3 mm slice thickness axial cut, proton density image and volumetric 3 D images were obtained.

Follow up protocol

All the patients were followed up at first month, third month & sixth month from the day of the procedure. The data was collected on regular OPD visits & regular phone conversations with the patients & family members regarding the symptoms, general condition & surgical (including ERCP and histopathology) follow up of the patients. At the end of 6 months, the patients with negative findings on EUS at the initial procedure, underwent MRCP scan or clinical follow up with LFT. After end of six month follow up, assessment was made to note for any change of diagnosis as determined by EUS. 16 patients were lost to follow up and analysis was done for 121 patients.

Definitions used

Positive diagnosis on EUS

Finding of a lesion that can be attributed as etiology of biliary dilatation.

Negative diagnosis on EUS

No lesion found that can be attributed as etiology of biliary dilatation or presence of normal bile duct diameter on EUS.

True positive

The etiologic lesion found on EUS was confirmed by later therapeutic or diagnostic procedure.

False Positive

The etiologic lesion found on EUS was changed by later therapeutic or diagnostic procedure.

True negative

The absence of any etiologic lesion as noted on EUS, remained the same at the end of follow up period.

False negative

Etiologic lesion was not found on EUS but subsequently lesion was found on follow up imaging or ERCP as treatment of cholangitis.

Largest CBD diameter: patients with both MRCP and CECT abdomen reports showing biliary dilatation, the greater diameter of CBD among the images were taken as maximum CBD diameter.

All enrolled patients provided informed consent for participating in the study and also for the publication of study findings. The study protocol was approved by institutional ethical committee (IPGME & R Research Oversight Committee, Institute of Post Graduate Medical Education & Research, Kolkata; IRB No: IPGME&R/IEC/2020/552) and the study was done in compliance with Helsinki guidelines.

Statistical analysis

Categorical and continuous variables are presented as number (percentage) and median (range), respectively. Comparison between the groups was done with Mann–Whitney U test. Binary logistic regression was done to find the predictive factors for a positive diagnosis on EUS and also separately for pancreatic, bile duct and ampullary mass lesions. Receiver operating characteristic (ROC) curves were plotted for serum bilirubin, serum CA 19.9 and maximum CBD diameter to see their performance for a positive diagnosis on EUS, and cut-off value of these variables were selected to have a high specificity (> 90%) of a positive diagnosis on EUS. Area Under ROC curve (AUROC) with 95% confidence interval, standard error and p-values are provided. Sensitivity (Sn), positive predictive value (PPV), negative predictive value (NPV), likelihood ratios for positive (LR +) and negative (LR-) tests, pre-test and post-test odds were calculated for the cut-off values selected for the said variables [12]. All p values were two-sided and value < 0.05 was taken as statistically significant.

Statistical analysis was done using SPSS software (IBM Corp. Released 2013. IBM SPSS Statistics for Windows, Version 22.0. Armonk, NY: IBM Corp).

Results

Baseline characteristics

Complete follow up data of 121 patients were available for analysis. 51.2% of patients were male with median age of the cohort being 55 years. Most of the patients were symptomatic with abdominal pain (51.2%), jaundice (41.3%) and significant weight loss (25.8%) being the common presenting symptoms. Baseline characteristics are shown in Table 1. Table 1 Characteristics of the patients and outcome of endoscopic ultrasound examination

Variables	
Male/Total; n (%)	62/121 (51.2)	
Age (years); Median (IQR)	55 (40–61)	
Clinical presentation; n (%)	
 a) Symptomatic patients	119 (98.3)	
 b) Abdominal pain	62 (51.2)	
 c) Jaundice	50 (41.3)	
 d) Cholangitis (Charcot’s triad)	8 (6.6)	
 e) Abdominal lump	3 (2.6)	
 f) Significant weight loss	31 (25.8)	
 g) Anorexia	29 (24.2)	
Subjects with Comorbidity; n (%)	66 (54.5)	
Type of Comorbidity; n (%)	
 a) Diabetes	25 (20.6)	
 b) Hypertension	26 (21.4)	
 c) CAD	6 (4.9)	
 d) Dyslipidemia	2 (1.6)	
 e) COPD	1 (0.8)	
 f) Others	2 (1.6)	
 g) Multiple	4 (3.2)	
History of surgery; n (%)	23 (19%)	
Bilirubin (Total) (mg/dL); Median (IQR)	1.7 (1.1–8.2)	
AST (IU/L) categories; n (%)		
 a) Normal	49 (40.5)	
 b) < 2X ULN	33 (27.3)	
 c) > 2XULN	39 (32.2)	
ALT (IU/L) categories; n (%)	
 a) Normal	49 (40.5)	
 b) < 2X ULN	33 (27.3)	
 c) > 2XULN	39 (32.2)	
ALP (IU/L) categories; n (%)	
 a) Normal	41 (33.9)	
 b) < 2X ULN	15 (12.4)	
 c) > 2XULN	65 (53.7)	
CA 19.9 (U/L); Median (IQR)	23 (3–267)	
CA 19.9 categories; n (%)		
 a) Normal	52 (42.9)	
 b) < 2X ULN	7 (5.7)	
 c) > 2X ULN	27 (22.3)	
 d) Not available	35 (28.9)	
Outcome; n (%)		
 a) Normal CBD	16 (13.2)	
 b) Idiopathic dilated CBD /Choledochal cyst	38 (31.4)	
 c) Ampullary neoplasm	29 (24)	
 d) Pancreatic mass	14 (11.6)	
 e) CBD calculus / worm	8 (6.6)	
 f) CBD/GB mass	7 (5.8)	
 g) Lymph node	5 (4.1)	
 h) Chronic pancreatitis	4 (3.3)	
Abbreviations: IQR Interquartile range represented as 25th and 75th percentile values, CAD Coronary artery disease, COPD Chronic obstructive pulmonary disease, AST Aspartate aminotransferase, ULN Upper limit of normal, ALT Alanine aminotransferase, ALP Alkaline phosphatase, CA 19.9 Carbohydrate antigen 19.9, CBD Common bile duct, GB Gall bladder

Outcome of EUS examination

EUS was able to find out lesions responsible for biliary dilatation in more than half of the cases (67 out of 121 or 55.4%). Ampullary neoplasm, pancreatic mass lesion and bile duct calculus or worm were the common pathologies detected by EUS. In 54 (44.6%) patients, EUS did not find out any lesion attributable to biliary dilatation. Choledochal cyst was the commonest benign lesion. Outcome of EUS shown in Table 1. We performed EUS-FNAC in total ten (10) patients. Three patients of < 50 years of age with pancreatic SOL where diagnoses other than adenocarcinoma were considered. Two (2) patients with CCP and mass formation and five (5) patients with lymph nodes underwent EUS-FNAC.

Median (range) dimension of maximum & minimum diameter of the lesions picked up by EUS were 19 (10–27) and 15 (9–20) mm respectively (Table 2). Table 2 Dimensions of the lesions detected on EUS as the etiology of biliary obstruction

	Median (Range)	
	Overall	
Maximum dimension in mm	19 (10–27)	
Minimum dimension in mm	15 (9–20)	
	Ampullary lesion	
Maximum dimension in mm	17 (10–24)	
Minimum dimension in mm	14 (9–20)	
	Pancreatic lesion	
Maximum dimension in mm	20.5 (17–27)	
Minimum dimension in mm	16 (10–20)	
	Bile duct lesion	
Maximum dimension in mm	20 (12–23)	
Minimum dimension in mm	12 (10–16)	
	Bile duct calculus	
Maximum dimension in mm	4 (3.4–5.2)	
Abbreviation: EUS Endoscopic ultrasound

EUS findings with normal side view endoscopy examination

Twenty-nine (29) of the patients out of 121 with complete follow up data was noted to have normal finding on side view endoscopy. Among them eight & four patients were diagnosed with ampullary and pancreatic neoplasm. At the end of follow up, EUS diagnosis was confirmed (with surgical biopsy) in six of the patients with ampullary neoplasm and all those i.e. four with pancreatic neoplasm. Thus, EUS detected neoplastic condition in almost one third (10 out of 29 or 34.5%) of subjects with normal side view endoscopy examination. The other notable diagnoses of patients with normal side view examination were choledochal cyst (10 out of 29 or 34.5%), choledocholithiasis & chronic pancreatitis (two each out of 29 or 7%).

Comparison between groups with positive or negative diagnosis on EUS

Among the clinico epidemiological factors, male sex and proportion of patients with jaundice, anorexia and significant weight loss at presentation were significantly higher in the group with a positive diagnosis on EUS. Median value of serum total bilirubin, serum CA 19.9 along with median diameter of common bile duct on imaging (trans abdominal ultrasound, MRCP, CECT abdomen or the highest diameter of either CT or MRCP) were significantly higher in the group with positive diagnosis on EUS (Table 3). Table 3 Comparison between groups with or without etiological diagnosis after endoscopic ultrasonography

	Findings on EUS	P value	
Negative	Positive		
N = 54	N = 67		
Age in years; median (IQR)	55 (38–61)	54 (40–62)	0.93	
Male; n (%)	16 (29.6)	46 (68.7)	< 0.001	
Presence of comorbid illness n (%)	28 (51.9)	38 (56.7)	0.53	
Past surgical history n (%)	13 (24.1)	9 (13.4)	0.14	
Abdominal pain n (%)	27 (50.0)	29 (43.3)	0.44	
Fever n (%)	6 (11.1)	16 (23.9)	0.07	
Jaundice n (%)	8 (14.8)	48 (71.6)	< 0.001	
Significant weight loss n (%)	0	30 (44.7)	< 0.001	
Anorexia n (%)	2 (3.7)	26 (38.8)	< 0.001	
Baseline abnormal LFT n (%)	9 (16.7)	34 (50.7)	< 0.001	
Baseline total bilirubin in mg%; median (IQR)	1.2 (0.9–1.5)	6.0 (1.8–12.5)	< 0.001	
Baseline CA 19.9 in U/L; median (IQR)	10.5 (3–31)	97 (12.5–455.5)	< 0.001	
CBD diameter in USG in mm: mean ± SD	9 ± 2	12 ± 5	0.001	
CBD diameter in Cross sectional image in mm: mean ± SD	12 ± 3	15 ± 5	< 0.0001	
CBD diameter in MRCP in mm: mean ± SD	11 ± 3	14 ± 5	< 0.001	
CBD diameter in CT in mm: mean ± SD	11 ± 3	15 ± 5	< 0.001	
Abbreviations: EUS Endosonography, IQR Interquartile range, LFT Liver function test, CA 19.9 Carbohydrate antigen 19.9, CBD Common bile duct, USG Ultrasonography, SD Standard deviation, MRCP Magnetic resonance cholangiopancreatography, CT Computed tomography

Predictors for positive diagnosis on EUS

Multivariate regression analysis identified jaundice at presentation being the sole predictive factor for positive diagnosis on EUS and also for detecting ampullary and pancreatic lesion (Table 4). Anorexia and significant weight loss at presentation were also the predictors for detecting mass lesion in ampulla and common bile duct respectively. Table 4 Multivariate analysis for predictor of i) etiological diagnosis on endoscopic ultrasound ii) ampullary mass lesion iii) pancreatic mass lesion iv) common bile duct mass lesion

	Coefficient of regression	Standrad error	Odds ratio	95% Confidence interval	P value	
Etiological diagnosis on EUS (all etiologies combined)	
 Jaundice	2.47	0.67	11.89	3.19–44.30	< 0.0001	
Ampullary mass lesion	
 Jaundice	1.58	0.67	4.87	1.32–18.0	0.01	
 Anorexia	2.21	0.90	9.15	1.54–54.37	0.01	
Pancreatic mass lesion	
 Jaundice	1.59	0.69	4.93	1.26–19.29	0.02	
CBD mass lesion	
 Weight loss	2.72	1.21	15.25	1.42–163.69	0.02	

Threshold value for variables with high specificity for positive diagnosis on EUS:

Threshold value for baseline bilirubin of 10 mg%, for baseline CA 19.9 of 225 u/L and for largest CBD diameter of 16 mm were determined to have specificity of 98%, 95%, 92.5% respectively of finding a positive diagnosis on EUS (Fig. 1).Fig. 1 Receiver operating characteristic curve for positive diagnosis on EUS for serum bilirubin, serum CA 19.9 and maximum CBD diameter

Comparison between patients with or without jaundice at presentation

Fifty patients had jaundice as compared to 71 patients who were anicteric at presentation. In subgroup analysis, we noted that patients with jaundice at presentation also had higher proportion of patients with anorexia and significant weight loss at presentation compared to anicteric group (38% & 44% in icteric group compared to 14.3% & 12.9% respectively; p < 0.001 in both). The mean baseline level of CA 19.9 and mean diameter of CBD at baseline were also higher in former group (mean CA 19.9 level 171 U/l in icteric vs 13 U/l in anicteric group; mean CBD diameter 16 mm in icteric vs 11 mm in anicteric group; p < 0.001 in both). In terms of outcome, icteric group had significantly higher positive diagnosis compared to anicteric patients (90% in icteric vs 31% in anicteric group; p < 0.001) with ampullary or pancreatic mass being the common pathology in the former (ampullary mass in 44% and pancreatic mass in 22% of icteric patients) and ampullary mass and choledocholithiasis being the common finding in latter group (ampullary mass in 9.8% & choledocholithiasis in 8.4% of anicteric patients).

Diagnostic performance of EUS

Overall, EUS was found to have sensitivity, specificity and accuracy of 95.65, 94.23% and 95.04% respectively in providing etiologic diagnosis of dilated biliary tree. In subgroup analysis, it was noted that EUS had higher sensitivity and diagnostic accuracy in those presenting with jaundice compared to those without. Specificity of EUS was higher in those without jaundice compared to those with jaundice (Table 5). Table 5 Diagnostic performance of endoscopic ultrasound in etiological diagnosis of dilated extrahepatic bile duct

	Sensitivity	Specificity	Positive predictive value	Negative predictive value	Positive likelihood ratio	Negative likelihood ratio	Accuracy	
Overall	95.65	94.23	95.65	94.23	16.58	0.04	95.04	
Patients with jaundice	97.72	66.67	95.5	80	2.93	0.03	94	
Patients without jaundice	92	83.33	95.83	71.42	5.52	0.09	90.32	

Adverse events

No adverse events were reported in any of the patients undergoing the endoscopic ultrasound with or without FNA.

Discussion

Biliary dilatation as detected by transabdominal ultrasound often requires further evaluation with cross sectional imaging such as CT scan or MRI or both. All the above three modalities have their limitations in detecting etiological diagnosis in the given setting. Endoscopic ultrasound, despite being invasive in nature, has the advantage of being in close proximity to distal bile duct and pancreas to detect lesions which might be missed by cross sectional imaging. Thereby, EUS have close to 100% specificity in detecting benign lesions and greater than 90% sensitivity and accuracy in detecting pancreatic neoplasms [13, 14]. Few studies have looked into role of EUS for evaluation of dilated bile duct as detected by transabdominal ultrasound without subjecting the patients to cross sectional imaging [15, 16]. However, in most of the institutions, as of today, patients undergo cross sectional imaging in attempt to detect etiology for biliary dilatation and EUS is usually employed after non-contributory cross-sectional imaging. Multiple studies have analysed role of EUS in detecting etiology of biliary dilatation after non-contributory CT [17, 18] or MRCP [19, 20] or both in retrospective [17–21] and prospective [22] fashion.

Current study attempted to find the diagnostic role of EUS in this real-world scenario in prospective fashion. In this cohort, most of the patients were symptomatic as was noted in another prospective study [22]. In more than half of the cases (54%), EUS was able to detect lesion responsible for biliary dilatation in our cohort with ampullary neoplasm being the commonest detected pathology. Similarly, EUS was noted to establish a positive diagnosis in other studies with outcome in favour of either neoplastic [16, 22] or benign [15] etiologies.

This study identified clinical jaundice at presentation as a predictor for a positive diagnosis on EUS as well as for finding ampullary mass or pancreatic mass on EUS. Male sex, altered LFT, elevated pancreatic enzymes and dilated MPD with CBD were noted to be predictors in the retrospective study by Carriere et al. [17]. However, the later study employed bivariate analysis for the same instead of multivariate analysis as was done in present study. Pausawasdi et al. [23], noted that intrahepatic biliary dilatation, in addition to male sex and elevated aminotransferase and alkaline phosphatase were predictive of pathological obstruction. However, in contrast to the present study, it was retrospective in nature.

On the other hand, we found 31% patients without jaundice at presentation had a pathologic biliary obstruction. Ampullary mass and CBD calculus were the common pathologies detected in this subgroup. Similar observation was reported by Malik et al. [20], where periampullary diverticulum and choledocholithiasis were found to be the common reasons for biliary dilatation in anicteric patients. This study also noted that almost one third of patients with normal side view endoscopy examination had pathologic obstruction detected by EUS.

Our study identified a threshold for serum bilirubin, CA 19.9 and CBD diameter to have a high specificity (98, 95, 92.5% respectively) of positive diagnosis on EUS. The sensitivity of EUS at those threshold values go down below 50%. However, EUS being an invasive test which is done at a later part of diagnostic algorithm, threshold for high specificity was chosen at the cost of low sensitivity.

In this study, EUS was noted to have high sensitivity, specificity, positive predictive value and diagnostic accuracy (~ 95%, 94%, 95%, 95% respectively) in etiological diagnosis of dilated biliary tree. In the meta-analysis done by Garrow D et al. [6], pooled sensitivity and specificity of EUS were noted to be 88% and 90% respectively with higher sensitivity and specificity noted for benign conditions compared to neoplastic ones. A recent prospective study by Atalla et al. [22] also revealed sensitivity, specificity and diagnostic accuracy of EUS was more than 98%. These figures corroborate with the findings in our study.

This study addresses the role of endoscopic ultrasound as a diagnostic modality in a common clinical scenario where the conventional and often used imaging techniques fail to provide an etiologic answer. The study identifies clinical predictors of finding any positive diagnosis on endoscopic ultrasound and also separately the same for pancreatic, bile duct or ampullary lesions. Threshold for biochemical and imaging parameters were ascertained with high specificity of etiological diagnosis established by EUS. Detection of pathologic lesions by EUS in almost one-third of patients with normal side view endoscopy examination also affirms role of EUS in diagnostic algorithm. The study being prospective in nature, it circumvents the drawbacks of cross-sectional observational studies and helps us to corroborate the findings of endoscopic ultrasonography during the follow up duration of the patients. Thus, diagnostic performance of endoscopic ultrasound in this context was ascertained.

Single centre observation with short duration of follow up (six months) for patients without any positive diagnosis on EUS are the drawbacks of the study. We did not perform any cholangioscopy or brush cytology for dilated CBD without obvious mass lesion, and therefore there was a chance of missing slow growing malignant stricture of bile duct which might not be clinically apparent in a follow up duration of six months. Most of the patients also came with the CT/MRI reports from outside as they were referred to our institute as it is a tertiary referral centre. Many of the CT scans were also not of pancreatic protocol. The possible interobserver variability along with technical difference of image acquisition at baseline cross sectional imaging studies (as they were from different centres and interpreted by different radiologists) can be cited as a drawback of this study. The study also did not seek to evaluate role of elastography or contrast EUS as the modalities were not available at the place of study.

In conclusion, EUS provides considerable diagnostic yield with high accuracy in patients with dilated biliary tree and non-diagnostic cross-sectional imaging (Fig. 2). Therefore, EUS should be included in diagnostic algorithm of dilated biliary tree, even with normal side view endoscopy examination and especially in symptomatic patients with bilirubin > 10 mg% and CBD diameter of more than 16 mm.Fig. 2 Sensitivity, positive predictive value & accuracy of endoscopic ultrasound are close to 95% for establishing diagnosis in patients with dilated biliary tree and non diagnostic cross sectional imaging

Abbreviations

CT Computed tomography

MRI Magnetic resonance imaging

EUS Endoscopic ultrasound

FNAC Fine needle aspiration cytology

ERCP Endoscopic retrograde cholangiopancreatography

CBD Common bile duct

USG Transabdominal ultrasound

MRCP Magnetic resonance cholangiopancreatography

LFT Liver function test

CA 19.9 Carbohydrate antigen 19.9

OPD Out patient department

ROC Receiver operating characteristic

AUROC Area under ROC curve

Sn Sensitivity

PPV Positive predictive value

NPV Negative predictive value

LR +  Positive likelihood ratios

LR Negative likelihood ratios

Acknowledgements

Radiologists in the department of Radiology and Gastrointestinal Radiology department of IPGME & R, Kolkata for their inputs and interpretation of abdominal images including cross sectional imaging. Pathologists in the department of GI pathology of IPGME & R for their contribution of providing results of EUS guided FNAC and surgical biopsies.

Ethical statement

All procedures followed were in accordance with the ethical standards of the responsible committee on human experimentation (institutional and national) and with the Helsinki Declaration of 1964 and later versions.

Authors’ contributions

AM, KD, DM, GKD contributed to the study conception and design. Material preparation, data collection and analysis were performed by AM, K, K D, D M, K D. The first draft of the manuscript was written by DM and all authors commented on previous versions of the manuscript. All authors read and approved the final manuscript.

Funding

No funding was received for this study.

Availability of data and materials

The datasets used and/or analysed during the current study are available from the corresponding author on reasonable request.

Declarations

Ethics approval and consent to participate

Study protocol was approved by institutional ethical committee (IPGME & R Research Oversight Committee, Institute of Post Graduate Medical Education & Research, Kolkata; IRB No: IPGME&R/IEC/2020/552, dated 10/08/2020). Informed consent for it was obtained from all patients for being included in the study.

Consent for publications

Consent for it was obtained from all patients for publication of the result of the study.

Competing interests

The authors declare no competing interests.

Publisher’s Note

Springer Nature remains neutral with regard to jurisdictional claims in published maps and institutional affiliations.
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References

1. Blackbourne LH Earnhardt RC Sistrom CL Abbitt P Jones RS The sensitivity and role of ultrasound in the evaluation of biliary obstruction Am Surg 1994 60 683 690 8060040
Blackbourne LH, Earnhardt RC, Sistrom CL, Abbitt P, Jones RS. The sensitivity and role of ultrasound in the evaluation of biliary obstruction. Am Surg. 1994;60:683–90.8060040
2. Koenigsberg M Wiener SN Walzer A The accuracy of sonography in the differential diagnosis of obstructive jaundice: a comparison with cholangiography Radiology 1979 133 157 165 10.1148/133.1.157 472285
Koenigsberg M, Wiener SN, Walzer A. The accuracy of sonography in the differential diagnosis of obstructive jaundice: a comparison with cholangiography. Radiology. 1979;133:157–65.472285 10.1148/133.1.157
3. Pedrosa CS Casanova R Lezana AH Fernandez MC Computed tomography in obstructive jaundice. Part II: the cause of obstruction Radiology. 1981 139 635 45 10.1148/radiology.139.3.7232730 7232730
Pedrosa CS, Casanova R, Lezana AH, Fernandez MC. Computed tomography in obstructive jaundice. Part II: the cause of obstruction. Radiology. 1981;139:635–45.7232730 10.1148/radiology.139.3.7232730
4. Kim HC Park SH Park SI Three-dimensional reconstructed images using multidetector computed tomography in evaluation of the biliary tract Abdom Imaging 2004 29 472 478 10.1007/s00261-003-0123-x 14716449
Kim HC, Park SH, Park SI, et al. Three-dimensional reconstructed images using multidetector computed tomography in evaluation of the biliary tract. Abdom Imaging. 2004;29:472–8.14716449 10.1007/s00261-003-0123-x
5. Romagnuolo J Bardou M Rahme E Joseph L Reinhold C Barkun AN Magnetic resonance cholangiopancreatography: a meta-analysis of test performance in suspected biliary disease Ann Intern Med 2003 139 547 557 10.7326/0003-4819-139-7-200310070-00006 14530225
Romagnuolo J, Bardou M, Rahme E, Joseph L, Reinhold C, Barkun AN. Magnetic resonance cholangiopancreatography: a meta-analysis of test performance in suspected biliary disease. Ann Intern Med. 2003;139:547–57.14530225 10.7326/0003-4819-139-7-200310070-00006
6. Garrow D Miller S Sinha D Endoscopic ultrasound: a meta-analysis of test performance in suspected biliary obstruction Clin Gastroenterol Hepatol 2007 5 616 623 10.1016/j.cgh.2007.02.027 17478348
Garrow D, Miller S, Sinha D, et al. Endoscopic ultrasound: a meta-analysis of test performance in suspected biliary obstruction. Clin Gastroenterol Hepatol. 2007;5:616–23.17478348 10.1016/j.cgh.2007.02.027
7. Chhoda A Dawod S Grimshaw A Gunderson C Mahadev S Evaluation of diagnostic yield of EUS among patients with asymptomatic common bile duct dilation: systematic review and meta-analysis Gastrointest Endosc 2021 94 890 901.e8 10.1016/j.gie.2021.07.002 34245751
Chhoda A, Dawod S, Grimshaw A, Gunderson C, Mahadev S. Evaluation of diagnostic yield of EUS among patients with asymptomatic common bile duct dilation: systematic review and meta-analysis. Gastrointest Endosc. 2021;94:890-901.e8.34245751 10.1016/j.gie.2021.07.002
8. Baron RL Tublin ME Peterson MS Imaging the spectrum of biliary tract disease Radiol Clin North Am 2002 40 1325 1354 10.1016/S0033-8389(02)00045-3 12479714
Baron RL, Tublin ME, Peterson MS. Imaging the spectrum of biliary tract disease. Radiol Clin North Am. 2002;40:1325–54.12479714 10.1016/S0033-8389(02)00045-3
9. Cohen SM Kurtz AB Biliary sonography Radiol Clin North Am 1991 29 1171 1198 10.1016/S0033-8389(22)02472-1 1947040
Cohen SM, Kurtz AB. Biliary sonography. Radiol Clin North Am. 1991;29:1171–98.1947040 10.1016/S0033-8389(22)02472-1
10. Baron RL Computed tomography of the bile ducts Semin Roentgenol 1997 32 172 187 10.1016/S0037-198X(97)80005-3 9253068
Baron RL. Computed tomography of the bile ducts. Semin Roentgenol. 1997;32:172–87.9253068 10.1016/S0037-198X(97)80005-3
11. Niederau C Müller J Sonnenberg A Extrahepatic bile ducts in healthy subjects, in patients with cholelithiasis, and in postcholecystectomy patients: a prospective ultrasonic study J Clin Ultrasound 1983 11 23 27 10.1002/jcu.1870110106 6403584
Niederau C, Müller J, Sonnenberg A, et al. Extrahepatic bile ducts in healthy subjects, in patients with cholelithiasis, and in postcholecystectomy patients: a prospective ultrasonic study. J Clin Ultrasound. 1983;11:23–7.6403584 10.1002/jcu.1870110106
12. Trevethan R Sensitivity, Specificity, and Predictive Values: Foundations, Pliabilities, and Pitfalls in Research and Practice Front Public Health 2017 5 307 10.3389/fpubh.2017.00307 29209603
Trevethan R. Sensitivity, Specificity, and Predictive Values: Foundations, Pliabilities, and Pitfalls in Research and Practice. Front Public Health. 2017;5:307.29209603 10.3389/fpubh.2017.00307
13. Tse F Liu L Barkun AN Armstrong D Moayyedi P EUS: a meta-analysis of test performance in suspected choledocholithiasis Gastrointest Endosc 2008 67 235 244 10.1016/j.gie.2007.09.047 18226685
Tse F, Liu L, Barkun AN, Armstrong D, Moayyedi P. EUS: a meta-analysis of test performance in suspected choledocholithiasis. Gastrointest Endosc. 2008;67:235–44.18226685 10.1016/j.gie.2007.09.047
14. Dewitt J Devereaux BM Lehman GA Sherman S Imperiale TF Comparison of endoscopic ultrasound and computed tomography for the preoperative evaluation of pancreatic cancer: a systematic review Clin Gastroenterol Hepatol. 2006 4 717 25 10.1016/j.cgh.2006.02.020 16675307
Dewitt J, Devereaux BM, Lehman GA, Sherman S, Imperiale TF. Comparison of endoscopic ultrasound and computed tomography for the preoperative evaluation of pancreatic cancer: a systematic review. Clin Gastroenterol Hepatol. 2006;4:717–25 quiz 664.16675307 10.1016/j.cgh.2006.02.020
15. Songür Y Temuçin G Sahin B Endoscopic ultrasonography in the evaluation of dilated common bile duct J Clin Gastroenterol 2001 33 302 305 10.1097/00004836-200110000-00009 11588544
Songür Y, Temuçin G, Sahin B. Endoscopic ultrasonography in the evaluation of dilated common bile duct. J Clin Gastroenterol. 2001;33:302–5.11588544 10.1097/00004836-200110000-00009
16. Abou Bakr S Elessawy H Ghaly S Abo Elezz M Farahat A Zaghloul M Diagnostic accuracy of endoscopic ultrasound in evaluation of patients with obstructive jaundice: single-center experience Egypt Liver Journal 2021 12 1 6
Abou Bakr S, Elessawy H, Ghaly S, Abo Elezz M, Farahat A, Zaghloul M. Diagnostic accuracy of endoscopic ultrasound in evaluation of patients with obstructive jaundice: single-center experience. Egypt Liver Journal. 2021;12:1–6.
17. Carriere V Conway J Evans J Shokoohi S Mishra G Which patients with dilated common bile and/or pancreatic ducts have positive findings on EUS? J Interv Gastroenterol 2012 2 168 171 10.4161/jig.23739 23687603
Carriere V, Conway J, Evans J, Shokoohi S, Mishra G. Which patients with dilated common bile and/or pancreatic ducts have positive findings on EUS? J Interv Gastroenterol. 2012;2:168–71.23687603 10.4161/jig.23739
18. Sousa M Fernandes S Proença L Diagnostic yield of endoscopic ultrasonography for dilation of common bile duct of indeterminate cause Rev Esp Enferm Dig 2019 111 757 759 10.17235/reed.2019.6278/2019 31373506
Sousa M, Fernandes S, Proença L, et al. Diagnostic yield of endoscopic ultrasonography for dilation of common bile duct of indeterminate cause. Rev Esp Enferm Dig. 2019;111:757–9.31373506 10.17235/reed.2019.6278/2019
19. Rana SS Bhasin DK Sharma V Rao C Gupta R Singh K Role of endoscopic ultrasound in evaluation of unexplained common bile duct dilatation on magnetic resonance cholangiopancreatography Ann Gastroenterol 2013 26 66 70 24714761
Rana SS, Bhasin DK, Sharma V, Rao C, Gupta R, Singh K. Role of endoscopic ultrasound in evaluation of unexplained common bile duct dilatation on magnetic resonance cholangiopancreatography. Ann Gastroenterol. 2013;26:66–70.24714761
20. Malik S Kaushik N Khalid A EUS yield in evaluating biliary dilatation in patients with normal serum liver enzymes Dig Dis Sci 2007 52 508 512 10.1007/s10620-006-9582-6 17211694
Malik S, Kaushik N, Khalid A, et al. EUS yield in evaluating biliary dilatation in patients with normal serum liver enzymes. Dig Dis Sci. 2007;52:508–12.17211694 10.1007/s10620-006-9582-6
21. Oppong KW Mitra V Scott J Endoscopic ultrasound in patients with normal liver blood tests and unexplained dilatation of common bile duct and or pancreatic duct Scand J Gastroenterol 2014 49 473 480 10.3109/00365521.2014.881547 24472065
Oppong KW, Mitra V, Scott J, et al. Endoscopic ultrasound in patients with normal liver blood tests and unexplained dilatation of common bile duct and or pancreatic duct. Scand J Gastroenterol. 2014;49:473–80.24472065 10.3109/00365521.2014.881547
22. Atalla H Menessy A Hakim H Shiomi H Kodama Y Ghoneem E Clinical utility of linear endosonography in patients with unexplained biliary dilatation and negative MRCP, with predictors for detection of neoplastic lesions Egypt Liver Journal 2022 12 1 10 10.1186/s43066-021-00164-x
Atalla H, Menessy A, Hakim H, Shiomi H, Kodama Y, Ghoneem E. Clinical utility of linear endosonography in patients with unexplained biliary dilatation and negative MRCP, with predictors for detection of neoplastic lesions. Egypt Liver Journal. 2022;12:1–10.10.1186/s43066-021-00164-x
23. Pausawasdi N Hongsrisuwan P Kamani L Maipang K Charatcharoenwitthaya P Diagnostic Value of Endoscopic Ultrasonography for Common Bile Duct Dilatation without Identifiable Etiology Detected from Cross-Sectional Imaging Clin Endosc 2022 55 122 127 10.5946/ce.2021.122 34974680
Pausawasdi N, Hongsrisuwan P, Kamani L, Maipang K, Charatcharoenwitthaya P. Diagnostic Value of Endoscopic Ultrasonography for Common Bile Duct Dilatation without Identifiable Etiology Detected from Cross-Sectional Imaging. Clin Endosc. 2022;55:122–7.34974680 10.5946/ce.2021.122
