The clinical significance of bile duct sludge: is it different from bile duct stones?

Effect of hypoxia on aquaporins and hepatobiliary transport systems in human hepatic cells

OBJECTIVES

Hepatic ischemia and hypoxia are accompanied by reduced bile flow, biliary sludge and cholestasis. Hepatobiliary transport systems, nuclear receptors and aquaporins were studied after hypoxia and reoxygenation in human hepatic cells.

METHODS

Expression of Aquaporin 8 (AQP8), Aquaporin 9 (AQP9), Pregnane X receptor (PXR), Farnesoid X receptor (FXR), Organic anion transporting polypeptide 1 (OATP1), and the Multidrug resistance-associated protein 4 (MRP4) were investigated in induced pluripotent stem cells (iPSCs) derived hepatic cells and the immortalized hepatic line HepG2. HepG2 was subjected to combined oxygen and glucose deprivation for 4 h followed by reoxygenation.

RESULTS

Expression of AQP8 and AQP9 increased during differentiation in iPSC-derived hepatic cells. Hypoxia did not alter mRNA levels of AQP8, but reoxygenation caused a marked increase in AQP8 mRNA expression. While expression of OATP1 had a transient increase during reoxygenation, MRP4 showed a delayed downregulation. Knock-down of FXR did not alter the expression of AQP8, AQP9, MRP4, or OATP1. Post-hypoxic protein levels of AQP8 were reduced after 68 h of reoxygenation compared to normoxic controls.

CONCLUSIONS

Post-transcriptional mechanisms rather than reduced transcription cause reduction in AQP8 protein concentration after hypoxia-reoxygenation in hepatic cells. Expression patterns differed between hepatobiliary transport systems during hypoxia and reoxygenation.

IMPACT

Expression of AQP8 and AQP9 increased during differentiation in induced pluripotent stem cells. Expression of hepatobiliary transporters varies during hypoxia and reoxygenation. Post-hypoxic protein levels of AQP8 were reduced after 68 h of reoxygenation. Post-transcriptional mechanisms rather than reduced transcription cause reduction in AQP8 protein concentration after hypoxia-reoxygenation in hepatic cells. Hypoxia and reoxygenation may affect aquaporins in hepatic cells and potentially affect bile composition.

Accuracy of SAGES, ASGE, and ESGE criteria in predicting choledocholithiasis

BACKGROUND

Patients with suspected choledocholithiasis (CDL) are stratified as high-risk (HR), intermediate-risk (IR), and low-risk (LR) according to the guidelines of Society of American Gastrointestinal and Endoscopic Surgeons (SAGES), American Society for Gastrointestinal Endoscopy (ASGE), and European Society of Gastrointestinal Endoscopy (ESGE). Although these approaches are invaluable, paucity of validation studies are currently available. This study aimed to evaluate the diagnostic accuracy of the above risk stratification criteria in predicting CDL.

METHODS

We conducted a retrospective cohort study of 280 patients with suspected CDL. All patients were stratified according to above professional societies as HR, IR, and LR, and diagnostic performance was evaluated.

RESULTS

In the HR group, area under the receiver operating characteristic curve (AUC) were 0.77 [95% confidence interval (CI), 0.70-0.84], 0.75 (95% CI, 0.68-0.81), and 0.74 (95% CI, 0.68-0.81) for SAGES, ASGE, and ESGE criteria, respectively. The diagnostic accuracy were 78.93% (81.13% sensitivity, 72.06% specificity), 75% (75.47% sensitivity, 73.53% specificity), and 70% (66.04% sensitivity, 82.35% specificity) for SAGES, ASGE, and ESGE criteria, respectively. Regarding the IR group, the diagnostic accuracy were 22.50% (16.98% sensitivity, 39.71% specificity), 25% (24.53% sensitivity, 26.47% specificity), and 30.00% (33.49% sensitivity, 19.12% specificity) for SAGES, ASGE, and ESGE criteria, respectively. The common bile duct stone (CBDS) visualized on imaging has the highest risk for CDL [odds ratio (OR), 13.59 (95% CI, 5.26-35.12)], followed by CBDS plus dilated common bile duct [OR, 13.33 (95% CI, 5.16-34.47)], CBDS plus cholangitis [OR, 13.33 (95% CI, 3.17-56.15)], and CBDS plus total bilirubin level > 1.7 mg/dL [OR, 9.89 (95% CI, 3.47-28.20)].

CONCLUSIONS

The current SAGES, ASGE, and ESGE criteria have acceptable diagnostic accuracy for CDL. The patients with visualized CBDS on imaging have the highest risk for CDL.

Do endosonographers agree on the presence of bile duct sludge and the subsequent need for intervention?

Background and study aims  Endoscopic ultrasonography (EUS) is a tool widely used to diagnose bile duct lithiasis. In approximately one out of five patients with positive findings at EUS, sludge is detected in the bile duct instead of stones. The objective of this study was to establish the agreement among endosonographers regarding: 1. presence of common bile duct (CBD) stones, microlithiasis and sludge; and 2. the need for subsequent treatment. Patients and methods  30 EUS videos of patients with an intermediate probability of CBD stones were evaluated by 41 endosonographers. Experience in EUS and endoscopic retrograde cholangiopancreatography, and the endosonographers' type of practices were recorded. Fleiss' kappa statistics were used to quantify the agreement. Associations between levels of experience and both EUS ratings and treatment decisions were investigated using mixed effects models. Results  A total of 1230 ratings and treatment decisions were evaluated. The overall agreement on EUS findings was fair (Fleiss' κ 0.32). The agreement on presence of stones was moderate (κ 0.46). For microlithiasis it was fair (κ 0.25) and for sludge it was slight (κ 0.16). In cases with CBD stones there was an almost perfect agreement for the decision to subsequently perform an ERC + ES. In case of presumed microlithiasis or sludge an ERC was opted for in 78 % and 51 % of cases, respectively. Differences in experience and types of practice appear unrelated to the agreement on both EUS findings and the decision for subsequent treatment. Conclusions  There is only slight agreement among endosonographers regarding the presence of bile duct sludge. Regarding the need for subsequent treatment of bile duct sludge there is no consensus.

One-step percutaneous transhepatic cholangioscopic lithotripsy in patients with choledocholithiasis

BACKGROUND

Endoscopic retrograde cholangiopancreatography (ERCP) may be inappropriate for most patients with choledocholithiasis. This study aimed to evaluate one-step percutaneous transhepatic cholangioscopic lithotripsy (PTCSL) in the treatment of patients with choledocholithiasis who could not undergo ERCP (e.g., failed ERCP, altered anatomy, and/or contra-indications).

METHOD

This was a retrospective single-centre series of 67 patients who underwent choledocholithiasis between November 2015 and March 2018: 35 with one-step PTCSL (Group A) and 32 with laparoscopic common bile duct (CBD) exploration (Group B).

RESULTS

Compared with Group B, Group A showed shorter duration of operation, length of stay in the hospital, postoperative hospital stay, postoperative drainage time, and time to oral intake (all P<0.05). Intraoperative blood loss, costs, conversion to open surgery (one in group A vs. seven in group B; P=0.023), and bile leakage (none in group A vs. four in group B; P=0.047) were lower in Group A than in Group B. There were no significant differences between the two groups regarding the intraoperative clearance rate, ultimate clearance rate, and several postoperative complications.

CONCLUSION

One-step PTCSL could be an alternative for patients with choledocholithiasis, especially when ERCP is not feasible.

Upper Gastrointestinal Bleeding With Hemobilia Caused by Gallstones

BACKGROUND

Hemobilia refers to bleeding in the biliary tract, commonly due to iatrogenic, traumatic, and neoplastic causes. It is a rare source of upper gastrointestinal hemorrhage, but it can be severe and fatal. However, gallstones account for 5%-15% of hemobilia cases.

CASE REPORT

A 60-year-old woman with diabetes mellitus and chronic kidney disease visited the emergency department with complaints of epigastric pain and vomiting of coffee ground-like content for 2 days. Physical examination revealed epigastric tenderness and hyperactive bowel sounds. Laboratory tests showed anemia with a hemoglobin count of 10.7 mg/dL and elevated liver function tests with total and direct bilirubin levels of 3.6 mg/dL and 2.5 mg/dL, respectively. Panendoscopy showed oozing of coffee ground-like material at the orifice of the ampulla of Vater and second portion of the duodenum, leading to suspicion of hemobilia. After admission, endoscopic retrograde cholangiopancreatography revealed common bile duct (CBD) dilatation with choledocholithiasis, biliary sludge, and filling defect at the middle section of the CBD. Endoscopic sphincterotomy with balloon lithotripsy was performed. After biliary decompression and broad-spectrum antibiotic administration, abdominal pain was relieved, and liver enzyme and total bilirubin levels improved. Symptoms of hemobilia depend on the bleeding rate and presence of bile duct obstructions due to clots. Minor and slow bleeding tend to form clots and cause biliary obstruction. WHY SHOULD AN EMERGENCY PHYSICIAN BE AWARE OF THIS?: Although minor hemobilia may remain asymptomatic and tends to resolve spontaneously, the cause of hemobilia must be corrected to prevent recurrent bleeding or obstruction.

Biliary spontaneous dislodgement spiral stent for patients who underwent mechanical lithotripsy

BACKGROUND

The incidence of post-endoscopic retrograde cholangiopancreatography (ERCP) cholangitis (PEC) in patients who underwent mechanical lithotripsy (ML) for large stone removal is high (up to 13.3%). One of the main causes is remaining small fragments or sludge that can impair normal biliary drainage. Endoscopic placement of a nasobiliary tube or a conventional plastic biliary stent has been commonly used under such conditions, but the patient may suffer from significant discomfort after the placement of a nasobiliary tube, while additional endoscopy is required for stent removal. We developed a biliary spontaneous dislodgement spiral stent (BSDSS) to overcome those shortcomings.

AIM

To evaluate the feasibility, safety, and effectiveness of inserting a BSDSS for patients who underwent ML for large stone removal.

METHODS

We conducted a single-center, retrospective, cohort study at West China Hospital, Sichuan University. A total of 91 consecutive patients with large biliary stones (≥ 10 mm) in the common bile duct who underwent ML between November 2017 and July 2018 were included. The 49 eligible patients were divided into the BSDSS group and the nasobiliary tube group. Technical success, post-ERCP adverse events (including PEC, post-ERCP pancreatitis, stone recurrence, BSDSS retention, self-extraction and dislocation of the nasobiliary tube), drainage time, and postoperative stay were measured and compared.

RESULTS

Twenty-one patients in the BSDSS group and 28 patients in the nasobiliary tube group were included in the analyses. The baseline characteristics and clinical information were similar in the two groups. Insertions of BSDSS and nasobiliary tube were technically successful in all 49 patients. There was no significant difference in the incidence of overall post-ERCP adverse events between the two groups (4.8% in the BSDSS group vs 17.9% in the nasobiliary tube group, P = 0.219). The median duration of drainage time (3 d in the BSDSS group vs 4 d in the nasobiliary tube group) and length of postoperative stay (4 d in the BSDSS group vs 5 d in the nasobiliary tube group) also did not differ (P = 0.934, and P = 0.223, respectively).

CONCLUSION

Endoscopic placement of a BSDSS appears to be feasible, safe and effective for patients who underwent ML for large stone removal.

Efficacy of endoscopic ultrasound after removal of common bile duct stone

Objective: Endoscopic retrograde cholangiopancreatography (ERCP) is a standard procedure for choledocholithiasis. Nonetheless, the recurrence rate remains quite high. This study aimed to investigate the prevalence and related factors of remnant biliary stone or sludge using endoscopic ultrasound (EUS) after the removal of common bile duct (CBD) stone and to evaluate the long-term clinical outcomes. Methods: A prospective study enrolling a consecutive series of patients who underwent ERCP for CBD stone removal was performed between June 2014 and November 2015. Following confirmation of complete CBD stone removal by the operator, EUS was performed to determine whether biliary stone or sludge remained. Patients underwent cholecystectomy if a gallstone was identified and were subsequently followed up at a regular interval of 3-6 months. We investigated whether symptomatic recurrence would occur. Results: A total of 130 patients were enrolled. The presence of remnant biliary stone or sludge after ERCP was confirmed in 36.9% (48/130) of patients. Acute angulation of the distal CBD was the sole factor associated with remnant biliary stone or sludge (p < .01). During the follow-up period, the overall recurrence rate was 17.7% (23/130). Recurrent symptomatic choledocholithiasis was predicted by remnant biliary sludge and large CBD diameter in multivariate analysis. Conclusions: Acute angulation of the distal CBD was associated with remnant biliary stone or sludge after ERCP. Remnant biliary sludge on EUS and large CBD diameter were strong predictors of symptomatic recurrence. EUS evaluation following CBD stone removal could be an effective strategy in the treatment of choledocholithiasis.

Restrictive strategy versus usual care for cholecystectomy in patients with gallstones and abdominal pain (SECURE): a multicentre, randomised, parallel-arm, non-inferiority trial

BACKGROUND

International guidelines advise laparoscopic cholecystectomy to treat symptomatic, uncomplicated gallstones. Usual care regarding cholecystectomy is associated with practice variation and persistent post-cholecystectomy pain in 10-41% of patients. We aimed to compare the non-inferiority of a restrictive strategy with stepwise selection with usual care to assess (in)efficient use of cholecystectomy.

METHODS

We did a multicentre, randomised, parallel-arm, non-inferiority study in 24 academic and non-academic hospitals in the Netherlands. We enrolled patients aged 18-95 years with abdominal pain and ultrasound-proven gallstones or sludge. Patients were randomly assigned (1:1) to either usual care in which selection for cholecystectomy was left to the discretion of the surgeon, or a restrictive strategy with stepwise selection for cholecystectomy. For the restrictive strategy, cholecystectomy was advised for patients who fulfilled all five pre-specified criteria of the triage instrument: 1) severe pain attacks, 2) pain lasting 15-30 min or longer, 3) pain located in epigastrium or right upper quadrant, 4) pain radiating to the back, and 5) a positive pain response to simple analgesics. Randomisation was done with an online program, implemented into a web-based application using blocks of variable sizes, and stratified for centre (academic versus non-academic and a high vs low number of patients), sex, and body-mass index. Physicians and patients were masked for study-arm allocation until after completion of the triage instrument. The primary, non-inferiority, patient-reported endpoint was the proportion of patients who were pain-free at 12 months' follow-up, analysed by intention to treat and per protocol. A 5% non-inferiority margin was chosen, based on the estimated clinically relevant difference. Safety analyses were also done in the intention-to treat population. This trial is registered at the Netherlands National Trial Register, number NTR4022.

FINDINGS

Between Feb 5, 2014, and April 25, 2017, we included 1067 patients for analysis: 537 assigned to usual care and 530 to the restrictive strategy. At 12 months' follow-up 298 patients (56%; 95% CI, 52·0-60·4) were pain-free in the restrictive strategy group, compared with 321 patients (60%, 55·6-63·8) in usual care. Non-inferiority was not shown (difference 3·6%; one-sided 95% lower CI -8·6%; p_{non-inferiority}=0·316). According to a secondary endpoint analysis, the restrictive strategy resulted in significantly fewer cholecystectomies than usual care (358 [68%] of 529 vs 404 [75%] of 536; p=0·01). There were no between-group differences in trial-related gallstone complications (40 patients [8%] of 529 in usual care vs 38 [7%] of 536 in restrictive strategy; p=0·16) and surgical complications (74 [21%] of 358 vs 88 [22%] of 404, p=0·77), or in non-trial-related serious adverse events (27 [5%] of 529 vs 29 [5%] of 526).

INTERPRETATION

Suboptimal pain reduction in patients with gallstones and abdominal pain was noted with both usual care and following a restrictive strategy for selection for cholecystectomy. However, the restrictive strategy was associated with fewer cholecystectomies. The findings should encourage physicians involved in the care of patients with gallstones to rethink cholecystectomy, and to be more careful in advising a surgical approach in patients with gallstones and abdominal symptoms.

FUNDING

The Netherlands Organization for Health Research and Development, and CZ healthcare insurance.

Laparoscopic Ultrasonography Versus Magnetic Resonance Cholangiopancreatography in Laparoscopic Surgery for Symptomatic Cholelithiasis and Suspected Common Bile Duct Stones

BACKGROUND

There continues to be controversy regarding the optimal screening modality in patients with symptomatic cholelithiasis and suspected common bile duct (CBD) stones. The aim of this study was to assess the diagnostic accuracy of laparoscopic ultrasonography (LUS) compared to magnetic resonance cholangiopancreatography (MRCP).

METHODS

Both LUS and MRCP were performed to evaluate the CBD stones and biliary anatomy in 200 patients undergoing laparoscopic surgery. Pre-, intra-, and postoperative data were collected prospectively and reviewed retrospectively.

RESULTS

Coexisting CBD stones were identified in 64 of 200 (32%) patients by surgical exploration or postoperative ERCP. For the detection of CBD stones, LUS yielded a positive predictive value of 100%, a negative predictive value of 99.3%, a sensitivity of 98.4%, and a specificity of 100%. Preoperative MRCP had a positive predictive value of 87.9%, a negative predictive value of 95.5%, a sensitivity of 90.6%, and a specificity of 94.1%. The non-random concordance between MRCP and LUS was considered to be excellent with a kappa coefficient of 0.92 (p < 0.01).

CONCLUSIONS

LUS can reduce the need for MRCP examination and can become the primary imaging method for the evaluation of CBD stones in laparoscopic surgery.

The Usefulness of Early Endoscopic Ultrasonography in Acute Biliary Pancreatitis with Undetectable Choledocholithiasis on Multidetector Computed Tomography

Background/Aims

EUS can detect bile duct stones (BDS) that are undetectable on multidetector computed tomography (MDCT). BDS associated with acute biliary pancreatitis (ABP) are small and tend to be excreted spontaneously. This study evaluated the usefulness of early EUS in patients with ABP and undetectable BDS on MDCT.

Methods

Forty-one patients with ABP and undetectable BDS on MDCT underwent EUS within 24 hours of admission and were diagnosed with BDS, sludge, dilated common bile duct (CBD), or normal CBD. ERCP was performed in patients with BDS, sludge, or clinical deterioration. The diagnostic yield and the effects of early EUS on morbidity, mortality, and the length of hospitalization were evaluated.

Results

EUS detected BDS or sludge in 48.8% of patients examined. BDS was the diagnosis in 13 patients, sludge in seven, and neither for 21 patients. ERCP was performed in 20 patients with BDS or sludge, in two patients with coexisting cholangitis, and in one patient with worsening liver function tests. ERCP identified BDS in 12 patients and sludge in seven. No lesions were diagnosed in four patients by ERCP. All patients improved, and the length of hospitalization in patients with ERCP was 9.0 days, without ERCP 7.1 days. Two patients with major complications by ERCP were hospitalized for a prolonged time.

Conclusions

Early EUS may be useful to select patients for therapeutic ERCP in cases of suspected ABP with undetectable BDS on MDCT.

Clinical Importance and Natural History of Biliary Sludge in Outpatients

OBJECTIVES

Gallbladder sludge is a common diagnosis on routine abdominal sonography, yet its clinical importance is uncertain, especially in outpatients. To determine its natural history and potential future complications in this setting, we reviewed the imaging and clinical histories of nonhospitalized patients with a diagnosis of sludge on sonography.

METHODS

We conducted a retrospective search of our institutional radiology information system for all sonographic reports using the key words "biliary sludge without gallstones" over a 3-year period. For each of the 104 patients with isolated biliary sludge on initial sonography, we reviewed the electronic medical records and all imaging for the development of pancreaticobiliary complications.

RESULTS

We found an overall prevalence of biliary sludge in outpatients of 1.8%. Of the 104 patients reviewed with a mean follow up of 630 days (21 months), 25 developed a pancreaticobiliary complication, including cholelithiasis, cholecystitis, choledocholithiasis, and pancreatitis. The most frequent complication was cholecystitis, with a total of 14 diagnoses (12 chronic acalculous and 2 acute with gallstones). An additional 6 patients developed gallstones without cholecystitis features; 4 patients developed pancreatitis; and 1 developed choledocholithiasis. Biliary sludge remained quiescent or resolved in 76% of patients.

CONCLUSIONS

Biliary sludge always represents a pathologic process, but its clinical implications among outpatients have not been previously investigated. Our ambulatory population developed pancreaticobiliary complications at similar rates as prior mixed-patient setting studies. Regardless of the patient setting, biliary sludge is likely of more clinical importance than previously regarded.

Tumefactive gallbladder sludge: the MRI findings

AIM

To evaluate the conventional and diffusion-weighted magnetic resonance imaging (MRI) images of tumefactive gallbladder sludge.

MATERIALS AND METHODS

The institutional review board approved this retrospective study. Between January 2006 and January 2015, 3478 patients were diagnosed with gallbladder sludge by ultrasonography (US). Of them, 12 patients (eight male, four female; mean age, 63.6 years) with 12 tumefactive gallbladder sludge lesions, who underwent subsequent MRI for further evaluation within 1 month, were included in this study. Data regarding the clinical features, presence of enhancement, and signal intensities of the T2-, T1-, and diffusion-weighted images were collected.

RESULTS

All cases of tumefactive sludge were detected incidentally. None of the patients had any predisposing factors for biliary sludge. The tumefactive gallbladder sludge was predominantly seen as a well-defined mass-like lesion. It showed hyperintensity on T1-weighted images (91.7%, 11/12), and variable signal intensities on T2-weighted images. Most of the tumefactive sludge lesions showed no enhancement on the dynamic phases (90%, 9/10). There were no cases with diffusion restriction. Among the patients with follow-up US data (n=7), all the lesions were found to have either disappeared or decreased in size.

CONCLUSION

Although tumefactive gallbladder sludge on US can mimic gallbladder cancer, its hyperintensity on a T1-weighted image, and the absence of enhancement and diffusion restriction on MRI images can be helpful for differentiating it from a tumorous condition.

Comparison of the clinical characteristics and imaging findings of acute cholangitis with and without biliary dilatation

OBJECTIVE

To evaluate the causes of acute cholangitis without biliary dilatation and to compare the clinical characteristics and the imaging findings between patients with acute cholangitis with and without biliary dilatation.

METHODS

93 patients diagnosed with acute cholangitis underwent contrast-enhanced CT. Among them, 17 patients were classified as not having biliary dilatation (Group 1) and 76 patients were classified as having biliary dilatation (Group 2). The causes of acute cholangitis were evaluated in both groups. Clinical characteristics and imaging findings were compared between the two groups.

RESULTS

The causes of acute cholangitis without biliary dilatation included common bile duct (CBD) stones (n=11), CBD sludge (n=3), a passed stone (n=1) and unknown causes (n=2). The total bilirubin levels of Group 1 were significantly lower than those of Group 2 (p=0.001). By contrast, Group 1 had higher median alanine aminotransferase (ALT) levels than Group 2 (p=0.04). The length of hospital stay was significantly longer in Group 2 than in Group 1 patients (p<0.001). In the imaging findings, the extent of transient hepatic attenuation differences (THADs) (p=0.003) were significantly smaller in Group 1 than in Group 2.

CONCLUSION

CBD stones and sludge were the most common causes of acute cholangitis in patients without biliary dilatation. These patients showed lower levels of bilirubin and higher levels of ALT than those with acute cholangitis with biliary dilatation, and had a shorter duration of hospital stay. The extent of THADs was the only discriminative CT finding between the two groups.

ADVANCES IN KNOWLEDGE

Acute cholangitis can present without biliary dilatation on imaging, and the most common causes are CBD stones and sludge. The patients with acute cholangitis without biliary dilatation have different clinical characteristics and imaging findings compared with those with acute cholangitis presenting with biliary dilatation.

Tissue harmonic sonography in the diagnosis of common bile duct stones: a comparison with endoscopic retrograde cholangiography

PURPOSE

To revisit the diagnostic accuracy of sonography in the detection of choledocholithiasis using modern equipment with tissue harmonic imaging (THI) and endoscopic retrograde cholangiopancreatography (ERCP) with sphincterotomy as the gold standard.

METHODS

A total of 107 patients with clinically suspected choledocholithiasis were examined with THI before undergoing ERCP. The sonographic findings that were prospectively evaluated included the presence of choledocholithiasis, size of common bile duct, sonographic view and patient position that best visualized the stone(s), visualization of the distal common duct, and duration of examination. The accuracy of sonography compared with ERCP and sphincterotomy was calculated.

RESULTS

Sonography correctly detected stones in 65 of 76 patients (sensitivity of 86%). The specificity and the overall accuracy were 87% and 86%, respectively. The sensitivity of sonography was higher with dilated extrahepatic duct (44% in patients with common bile duct measuring less than 6 mm in diameter, 82% between 6 and 10 mm, and 100% with common bile duct larger than 10 mm). The lateral approach with the patient in left lateral decubitus position of the patient was the most effective in 47% of the cases.

CONCLUSION

Sonography with THI is an accurate technique for the detection of choledocholithiasis that may be used as the first-choice technique to avoid unnecessary procedures in a high percentage of patients, especially those with dilated biliary tree.