Magnetic resonance cholangiopancreatography and laparoscopic bile duct exploration should be standard procedures for patients with the ice-breaking sign?

Abstract

The authors introduce a new magnetic resonance cholangiopancreatography (MRCP) radiologic feature, the “ice-breaking sign” (IBS), and present a retrospective case-control study comparing patients with common bile duct stones who exhibit the IBS with a control group without this sign. The two groups were matched using a propensity score based on patient age and sex. However, the matching process did not account for the size of the choledocholithiasis, which may represent a significant confounding factor. Both groups were not homogeneous. The authors advocate for the use of MRCP as the primary diagnostic tool to guide the decision. However, in clinical practice, MRCP availability is often limited, particularly when compared to endoscopic ultrasound, which may be more available. The authors compared the clinical course and therapeutic responses to cholangiopancreatography (ERCP) and laparoscopic common bile duct exploration (LCBDE) between the two groups. The results demonstrated a markedly low ERCP success rate in both the study and control, falling below international standards, whereas the success rate of LCBDE was only slightly reduced. Despite the study’s limitations and potential biases, the authors conclude that IBS is a valuable predictor for treatment planning and suggest that LCBDE should be considered the first-line approach. Despite its growing acceptance, LCBDE remains infeasible in many hospitals due to the steep learning curve

Key Words: Ice breaking sign; Magnetic resonance cholangiopancreatography; Choledocholithiasis; Laparoscopic bile duct exploration; Common bile duct stones treatment; Endoscopic retrograde cholangiopancreatography

Core Tip: The study makes a noteworthy contribution by identifying a novel magnetic resonance cholangiopancreatography radiologic sign, the "ice-breaking sign" (IBS), which may help define a subgroup of patients with common bile duct stones (CBDS) at increased risk for failure of endoscopic treatment. The authors conducted a retrospective case-control study comparing patients exhibiting the IBS with a control group of CBDS patients without this sign. The objective was to evaluate treatment outcomes in both groups following endoscopic retrograde cholangiopancreatography (ERCP) and laparoscopic common bile duct exploration (LCBDE). Despite the novel contribution, several limitations, including group heterogeneity and suboptimal ERCP success rates, weaken the strength of the conclusions. At present, the evidence is insufficient to establish the IBS as a reliable predictor for treatment planning or to support a general recommendation for LCBDE as a first-line therapy.

INTRODUCTION

Zhao et al[1] present an interesting and thought-provoking retrospective case-control study conducted between 2018 and 2023, involving patients with choledocholithiasis [common bile duct stones (CBDS)] confirmed by preoperative magnetic resonance cholangiopancreatography (MRCP) and treated with either laparoscopic common bile duct exploration (LCBDE) or endoscopic retrograde cholangiopancreatography (ERCP).

The authors describe a new radiological MRCP finding, referred to as the “ice-breaking sign” (IBS). This sign is characterized by distal common bile duct stenosis located below a filling defect, accompanied by proximal bile duct dilation.

The study analyzes the clinical course and therapeutic outcomes of patients with CBDS treated with ERCP and LCBDE, comparing those who exhibited the IBS to those who did not. The aim was to evaluate whether the presence of this sign could predict failure of endoscopic treatment and help identify patients who may benefit from primary surgical management with LCBDE.

THE IBS

The authors describe a partially novel radiologic sign termed the IBS, which bears resemblance to previously recognized signs such as the 'meniscus sign' and the 'beak sign,' without clearly comparing or distinguishing it from these established findings. They propose assessing the presence of this sign in all patients with CBDS before determining the most appropriate therapeutic approach.

To evaluate its clinical relevance, the authors compared a case group—patients with CBDS who displayed the IBS on MRCP—with a matched control group of CBDS patients who underwent the same treatments but did not exhibit the sign.

The authors confirm that the case group exhibited a significantly higher incidence of jaundice compared to those without the sign, suggesting that the IBS may indicate more severe biliary obstruction. However, the two groups were not homogeneous, which may impact the validity of the comparisons.

Based on their clinical experience with this patient cohort, the aim of the study was to test the hypothesis that this radiologic sign can help identify a subgroup of patients with CBDS who may present challenges for both endoscopic and surgical management. The authors conclude that, for these patients, LCBDE should be considered as the preferred first-line treatment option moving forward.

The IBS, as described by Zhao et al[1], refers to a filling defect accompanied by a distal common bile duct stricture (dCBD) and proximal common bile duct dilation. This radiologic sign resembles dCBD, which is one of the key features of the so-called ‘difficult bile duct stone’ group—a category well known for posing significant challenges to endoscopic treatment[2].

Additional features that define a “difficult bile duct stone” include the following: Stones larger than 15 mm; the shape and hardness of the stones (e.g., square or cylindrical); the number of calculi (more than three); location of calculi in the cystic duct or intrahepatic ducts; biliary anatomical anomalies; dCBD distal common bile duct stenosis; a sigmoid or sharply angulated common bile duct (angle greater than 135°); and a short common bile duct (less than 36 mm). Additional factors that may complicate endoscopic treatment include the presence of a peripapillary diverticulum, duodenal stenosis, and prior surgeries that alter gastrointestinal anatomy, such as Roux-en-Y or Billroth II reconstructions[3,4].

However, in this study, the dCBD associated with the IBS did not appear to be of organic origin. The authors indirectly demonstrate that many of the strictures seen on MRCP disappeared once the obstruction was relieved, supporting the notion that these are functional, rather than structural, narrowing of the bile duct.

MRCP FOR EVERY PATIENT WITH CBDS

Another important and clinically relevant point raised—though not directly stated—is the implication that MRCP should be performed routinely in all patients with CBDS, as part of the preoperative diagnostic approach outlined in their methodology.

The American Society for Gastrointestinal Endoscopy guidelines classify patients into different risk categories for CBDS. High-risk patients include those presenting with clinical jaundice, significant elevations in liver function tests, acute cholangitis, bile duct dilation, or direct visualization of CBDS on ultrasound (US). In such cases, it is recommended to proceed directly to ERCP.

Additional diagnostic studies, such as endoscopic ultrasound (EUS) or MRCP, are generally not indicated before ERCP, as they may delay definitive treatment and are unlikely to change the treatment plan in patients with a confirmed diagnosis of choledocholithiasis. Moreover, MRCP is not widely available in emergency departments, and elective scheduling is often delayed due to long waiting lists.

In clinical practice, an easily accessible and rapid imaging study, such as an abdominal computed tomography (CT) scan, may be conducted to confirm US findings and exclude alternative diagnoses, including underlying pancreaticobiliary malignancies.

For patients classified as intermediate risk—those presenting with non-conclusive signs such as mild liver function test abnormalities or biliary pain without jaundice—noninvasive imaging studies such as MRCP or EUS are the most recommended diagnostic options[5].

Today, the choice between the EUS and MRCP largely depends on local availability and institutional expertise. Both modalities offer high sensitivity and specificity: Approximately 95% and 97% for EUS, and 93% and 96% for MRCP, respectively[4,6].

Currently, there is insufficient evidence to support the superiority of one modality over the other in terms of cost-effectiveness, safety, or patient experience. Therefore, an individualized approach is recommended based on clinical context and available resources[7].

If the results of Zhao et al’s study[1] are confirmed, MRCP should be considered the first-line diagnostic tool for evaluating suspected choledocholithiasis, regardless of the patient’s risk stratification for CBDS[5].

TREATMENT OF CBDS

In patients with confirmed CBDS who are classified as high or intermediate risk based on US, CT scan, MRCP, or EUS—the recommended first-line therapeutic approach is preoperative ERCP, followed by laparoscopic cholecystectomy (LC).

Regarding the endoscopic treatment of difficult bile duct stones using ERCP, complementary techniques may be required during the procedure, such as balloon papilloplasty, cholangioscopy-assisted lithotripsy, extracorporeal shock wave lithotripsy, or biliary stenting with planned bile duct clearance in a subsequent session[2]. These factors can influence, and in some cases alter, the choice between endoscopic and surgical management.

Transcystic or transductal LCBDE is a well-established, safe, and effective technique for clearing bile duct stones during LC[8]. It is indicated in patients with choledocholithiasis confirmed by preoperative MRCP, EUS, or intraoperative cholangiography. It is also suitable for patients with altered gastrointestinal anatomy, such as those who have undergone Roux-en-Y gastric bypass or Billroth II reconstruction, where ERCP is technically challenging.

LCBDE enables the simultaneous treatment of choledocholithiasis and cholelithiasis in a single procedure, with success, efficacy, and safety rates comparable to those of ERCP.

The transcystic approach is safer and technically simpler, making it more accessible to general surgeons. In contrast, the transcholedochal approach provides better duct clearance and access to intrahepatic ducts, but it carries a higher risk of complications and requires more advanced surgical expertise[8,9].

LCBDE is indicated when ERCP fails or when local surgical expertise is available. If LCBDE is not feasible, open cholecystectomy with common bile duct exploration remains a viable rescue option.

Despite its advantages, LCBDE is not widely adopted as a first-line therapy in clinical practice. This is primarily due to limited availability and the uneven distribution of surgical expertise, particularly given the procedure’s steep and technically demanding learning curve.

Rogers et al[10] published a prospective study comparing two therapeutic strategies for the management of patients with confirmed choledocholithiasis and low anesthetic risk: LC combined with LCBDE (LC + LCBDE), and preoperative ERCP with sphincterotomy followed by LC (ERCP/S + LC). Both approaches demonstrated similar efficacy in clearing the bile duct; however, the LC + LCBDE group had a shorter hospital stay. No significant differences were observed between the groups regarding cost, patient acceptance, or reported quality of life.

LCBDE: THE PROPOSED FIRST-LINE TREATMENT FOR PATIENTS WITH CBDS AND THE “ICE-BREAKING” RADIOLOGIC SIGN

Zhao et al[1] utilized both ERCP and LCBDE as first-line therapeutic approaches for patients with CBDS. Upon analyzing outcomes in the subgroup of patients exhibiting IBS, they observed a significantly higher failure rate with ERCP compared to LCBDE. Based on these results, the authors propose that LCBDE should be the preferred first-line treatment for patients presenting with IBS.

They adopted a retrospective case-control design; however, several major methodological limitations raise substantial concerns about the validity and strength of the conclusions.

An undetermined number of patients who required conversion to open surgery were excluded from the study, without detailed justification. This exclusion likely removed a subgroup of more complex cases with higher morbidity, potentially introducing selection bias and limiting the generalizability of the findings.

Another source of bias was the construction of the control group using propensity score matching based solely on age and sex, without accounting for other critical variables related to difficult stones, such as stone diameter. As a result, the groups were not homogeneous and showed significant differences in key clinical features, including the incidence of jaundice, sepsis, stone size, and the need for lithotripsy, which was completely absent in the control group. All of these factors undoubtedly impact the study’s conclusions.

The therapeutic efficacy of ERCP in the control group was 80%, which is significantly lower than the widely accepted standard of 90%[11]. This may help explain the even lower success rate of 25% observed in the study group. Notably, 12 out of 16 patients in the study group who underwent ERCP experienced treatment failure; Among these, three spontaneously expelled the calculus, while the remaining nine were subsequently treated successfully with LCBDE.

It is important to note that the lower ERCP success rate of 25%, compared to the LCBDE success rate of 69.4%, likely does not reflect the expected outcomes for this subgroup of patients with difficult bile duct stones. However, despite the relatively low success rate of LCBDE in the study group (12 out of 47 procedures failed), this still reflects the complexity of the cases. Importantly, it is not significantly lower than the ERCP success rate in the same group. Moreover, the LCBDE success rate in the control group was 93.8%, which aligns well with international standards and further supports its reliability as a treatment option[12].

Marks and Al Samaraee[12] conducted a systematic review of 36 studies, reporting that LCBDE achieves a success rate greater than 84%, with an average hospital stay of 5.6 days and a conversion rate to open surgery ranging between 5%-8%. The transcystic approach was associated with better outcomes compared to the transductal approach, including lower morbidity, shorter operative time, and reduced hospital stay.

In this regard, the study’s strong recommendation to adopt LCBDE as the first-line treatment for CBDS in the presence of IBS is not fully supported. This conclusion is based on notably low ERCP success rates—even within the non-complex control group—and should be interpreted considering the methodological limitations and potential biases previously outlined.

If the authors’ conclusions are correct, the diagnostic and therapeutic approach to patients with symptomatic CBDS would require a significant shift. MRCP would need to be routinely performed to identify the IBS. If identified, patients should proceed directly to laparoscopic LCBDE.

However, this proposal diverges markedly from current clinical practice, where ERCP is typically the first-line treatment—often initiated based solely on US findings, with or without a CT scan. According to existing guidelines, MRCP or EUS is not deemed necessary for patients at high risk of CBDS and is considered optional for those at intermediate risk, as both imaging modalities offer similar diagnostic yield. The use of MRCP or EUS is often influenced by local resource availability. In many hospital emergency departments, MRCP remains limited in availability, and elective scheduling is often constrained by long waiting lists.

Moreover, it is essential to underscore why ERCP remains the gold standard and preferred first-line treatment for CBDS. Although comparative studies between LCBDE and ERCP have shown no significant differences in efficacy[7-9], LCBDE is limited by a steep learning curve and reduced availability, particularly outside specialized centers.

The SAGES in their guidelines: Clinical Spotlight Review: Laparoscopic Common Bile Duct Exploration and posted 14 December, 2017, referred to a recent study using the United States Nationwide Inpatient Sample found that only 7% of patients with common duct stones were treated with LCBDE as opposed to 93% with ERCP. In contrast, ERCP is more widely accessible and supported by advanced adjunctive tools, such as biliary stents, which can serve as effective rescue strategies comparable to T-tubes in surgical settings.

In summary, the study suggests that IBS identifies a subgroup of CBDS patients with difficult bile duct stones and severe biliary obstruction, marked by a distal bile duct stenosis that appears to be functional and reversible. Whether this sign can reliably predict a high ERCP failure rate—and therefore serve as a criterion for referring patients directly to first-line treatment with LCBDE—remains to be confirmed through future prospective studies.

We would like to emphasize that the true importance and significance of this study lie in the identification, explanation, and highlighting of a key MRCP radiologic sign that all clinicians should recognize, given its strong association with therapeutic challenges encountered during both ERCP and LCBDE. A logical next step would be to expand this research in a multicenter setting, with careful attention to minimizing the potential biases discussed in this editorial.

CONCLUSION

Despite the study’s methodological limitations and potential biases, it provides a valuable contribution by identifying a new MRCP radiologic sign that may help define a subgroup of CBDS patients at higher risk for endoscopic and LCBDE treatment. However, the recommendation to perform MRCP in all patients with CBDS remains debatable. Given the study’s design flaws and the unusually low ERCP success rates reported in both the case and control groups, the authors’ conclusions cannot be fully supported. Further prospective studies are needed to validate these findings and clarify their clinical implications.