Two-step approach: Stone extraction after covered stent placement in Mirizzi syndrome: Early experience from a retrospective study

Abstract

BACKGROUND

Mirizzi syndrome is characterized by large impacted stones and concomitant relative stenosis of the distal bile duct, and its management poses significant clinical challenges. The optimal endoscopic therapeutic strategy for this condition remains a subject of active debate in clinical practice.

AIM

To investigate endoscopic therapeutic approaches for Mirizzi syndrome.

METHODS

This was a retrospective, non-controlled, observational study conducted at Renji Hospital, School of Medicine, Shanghai Jiao Tong University. All patients were diagnosed with Mirizzi syndrome and underwent stone extraction after fully covered stent placement between June 2021 and June 2025. Step 1: A fully covered stent was left in the biliary tract for approximately 8 weeks to expand the narrowed bile duct. Step 2: Stent removal and stone extraction using balloons, basket catheters, or electrohydraulic lithotripsy.

RESULTS

A total of 23 patients (14 females, 9 males; median age 69 years) underwent two-step stent-assisted stone extraction. Fully covered stents were successfully implanted in 23 patients with a median dwell time of 63 days. The stone extraction success rate was 82.6% (19/23) and the median stone extraction time was 21.5 minutes. Five cases of cholecystitis and three cases of pancreatitis were reported.

CONCLUSION

To our knowledge, this is the first study to evaluate the feasibility and safety of stone extraction after covered stent placement in patients with Mirizzi syndrome. Stone extraction after covered stenting is a viable option for Mirizzi syndrome, particularly in patients unsuitable for prolonged endoscopic retrograde cholangiopancreatography or those with marked distal bile duct stenosis.

Key Words: Mirizzi syndrome; Endoscopic retrograde cholangiopancreatography; Stone extraction; Fully covered stent; Bile duct stone

Core Tip: Mirizzi syndrome is characterized by large impacted stones and concomitant relative stenosis of the distal bile duct. In this study, 23 patients underwent two-step stent-assisted stone extraction (stone extraction after covered stent placement). The stone extraction success rate was 82.6% (19/23) and the median stone extraction time was 21.5 minutes. The findings suggest that stone extraction after covered stent placement is a viable option for Mirizzi syndrome.

INTRODUCTION

The management of Mirizzi syndrome presents considerable complexity and challenges, particularly in cases involving large impacted stones[1]. Laparoscopic cholecystectomy for Mirizzi syndrome is often complicated by inflammatory adhesions in the Calot’s triangle, distorted anatomical relationships, and an increased risk of bile duct injury, frequently necessitating additional procedures such as T-tube or choledochojejunostomy[2,3]. For patients with Mirizzi syndrome classified as Csendes type III or IV, the intraoperative placement of a T-tube or biliary-enteric anastomosis is almost unavoidable.

Over the past few decades, endoscopic retrograde cholangiopancreatography (ERCP) using basket catheters, balloon catheters, and mechanical lithotripsy has emerged as the first-line treatment for common bile duct stones[4]. With the evolution of endoscopic techniques, novel therapeutic approaches have been developed for the treatment of Mirizzi syndrome. In cases involving large or impacted bile duct stones, electrohydraulic lithotripsy is a well-established endoscopic modality for stone extraction[5]; however, it requires prolonged procedure time and multiple lithotripsy sessions. Mirizzi syndrome is frequently characterized by large impacted stones and relative stenosis of the distal bile duct, particularly in Csendes types III and IV[6]. The optimal ERCP-based therapeutic strategy for Mirizzi syndrome remains the subject of ongoing clinical debate.

MATERIALS AND METHODS

Study design

This retrospective, non-controlled, observational study was conducted at Renji Hospital, School of Medicine, Shanghai Jiao Tong University. Data were collected from June 2021 to June 2025, with approval by the Ethics Committee of Renji Hospital (Approval No. LY2025-430-B). All patients were diagnosed with Mirizzi syndrome either before or during ERCP.

Inclusion criteria: (1) Definite diagnosis of Mirizzi syndrome confirmed by imaging and clinical findings; and (2) Treated with endoscopic placement of a temporary fully covered biliary stent, followed by second-stage endoscopic biliary stone extraction.

Exclusion criteria: (1) Concurrent malignant tumors of the digestive system, including biliary malignancy, gallbladder carcinoma, cholangiocarcinoma, and pancreatic carcinoma; (2) Previous history of biliary surgery or biliary reconstruction; and (3) Severe missing clinical data or loss to follow-up, rendering efficacy and adverse event assessment unavailable. The study flow chart is shown in Figure 1.

Figure 1 Study flow chart.

Study objective

Fully covered stents, which were tubular metal mesh scaffolds sheathed with a thin waterproof synthetic covering, were frequently employed in the treatment of biliary strictures[7]. The study aimed to evaluate the feasibility and safety of stone extraction after fully covered stent placement in patients with Mirizzi syndrome. The primary endpoint was stone retrieval success rate after the second-stage procedure, defined as the proportion of patients confirmed to have no residual biliary stones on postoperative imaging and endoscopic follow-up. Secondary endpoints mainly included: (1) The operative time of the first-stage and second-stage endoscopic procedures; and (2) The incidence of postoperative complications, including bleeding, perforation, cholecystitis, pancreatitis, and cholangitis. All adverse events occurring during and after the procedures were fully recorded.

All patients underwent stone extraction after fully covered stent placement. Step 1: Complete blood count, liver function, coagulation function, and abdominal magnetic resonance cholangiopancreatography/computed tomography were performed to identify the stone location and determine the Csendes type. Cholangiography was used to confirm common hepatic duct stricture and the site of stone impaction. A fully covered stent (typically 10 mm × 60 mm or 10 mm × 80 mm) was left in the biliary tract for approximately 8 weeks to expand the narrowed bile duct (Figure 2). The stent was placed with its proximal end positioned above the stone and its distal end passing through the duodenal papilla into the intestinal lumen; an appropriate stent length was selected for each patient's bile duct. Fasting was maintained for 24 hours after the procedure. Amylase, liver function, and infection markers were monitored. Prophylactic antibiotics, enzyme inhibition, and liver-protective therapy were administered. Step 2: The fully covered stent was grasped and retrieved. After biliary cholangiography, baskets or balloons were used to extract the impacted stones (Figure 3). Video 1 showed the procedure in a patient with Mirizzi syndrome.

Figure 2 Fully covered biliary stents were placed after evaluation by magnetic resonance cholangiopancreatography and cholangiography (step 1). A: Magnetic resonance cholangiopancreatography before fully covered stent placement. The orange arrow indicates the impacted stone; B: Cholangiography before fully covered stent placement. The orange arrow indicates the impacted stone; C: Fully covered stent placement; D: Cholangiography after fully covered stent placement. The patient previously underwent biliary stent placement (7 Fr × 7 cm).

Figure 3 Fully covered stent removal and stone extraction (step 2). A: Fully covered stent after placement for 8 weeks; B: Cholangiography after fully covered stent removal; C: Removed common bile duct stone.

Data management and statistical analysis

All consecutive Mirizzi syndrome patients undergoing ERCP were retrospectively enrolled at our center. Statistical analyses were performed using SPSS software (version 22.0; IBM Corp.). Continuous variables were summarized as mean, median, SD, minimum, and maximum values. Categorical variables were reported as n (%).

RESULTS

Patient characteristics

Between June 2021 and June 2025, 23 patients (14 females and 9 males; median age 69 years) underwent two-step stent-assisted stone extraction. The median stone diameter was 11.0 mm and median downstream bile duct diameter was 6.0 mm (Table 1).

Table 1 Patient characteristics.

Items	Value
Patients
Female	14
Male	9
Age (year)	69.0 (24.0, 82.0)
Maximum stone diameter (mm)	11.0 (7.0, 16.0)
Downstream bile duct diameter (mm)	6.0 (3.0, 9.0)
Stone number
≥ 3	7
< 3	16
Csendes type
I and II	5
III and IV	18
Previous ERCP	5

Data were presented as median (range) for continuous variables. ERCP: Endoscopic retrograde cholangiopancreatography.

Stone retrieval success rate

In step 1, fully covered stents were successfully implanted in 23 patients. The median stent placement time was 9.0 minutes. Subsequently, a fully covered stent was left in the biliary tract for approximately 8 weeks (median dwell time, 63 days). In step 2, stones were successfully extracted from 19 patients, while 4 patients still had residual stones. The median stone extraction time was 21.5 minutes. Four patients with Csendes type IV Mirizzi syndrome and impacted stones underwent electrohydraulic lithotripsy after fully covered stent removal. Among these, one patient achieved successful stone extraction, whereas three patients had residual stones and underwent staged lithotripsy. Post-extraction laparoscopic cholecystectomy was performed in 17 patients within 4 weeks (Table 2).

Table 2 Treatment outcomes and complication rates.

Items	Value
Covered stent time (minute)	9.0 (6.0, 17.0)
Difficult cannulation	2 (8.7)
Covered stent success	23 (100.0)
Covered stent dwell time (day)	63 (52, 86)
Stone extraction time (minute)	21.5 (7.0, 57.0)
Use of a basket for extraction	16 (69.6)
Use of a balloon for extraction	21 (91.3)
Stone extraction success	19 (82.6)
Residual stone	4 (17.4)
Following electrohydraulic lithotripsy	4 (17.4)
Following LC	17 (73.9)
Adverse event
Bleeding	0 (0)
Perforation	0 (0)
Pancreatitis	3 (13.0)
Cholangitis	0 (0)
Cholecystitis	5 (21.8)

Data were presented as n (%) for categorical variables and as median (range) for continuous variables. LC: Laparoscopic cholecystectomy.

Complication rates

No severe complications (e.g., bleeding, perforation, or cholangitis) occurred. Five cases of cholecystitis were reported. Three cases of pancreatitis were observed and resolved with conservative management (Table 2).

DISCUSSION

This study is the first report, to our knowledge, on the feasibility and safety of stone extraction after fully covered stent placement in Mirizzi syndrome. Our findings show that this approach might be effective and safe.

Due to large impacted stones and relative stricture of the distal bile duct, conventional extraction balloons or baskets often fail to remove the stones, making endoscopic retrieval challenging in cases of Mirizzi syndrome, particularly in Csendes types III and IV. Electrohydraulic lithotripsy is a conventional method for treating refractory common bile duct stones, with a reported stone clearance rate of 75.8%[8]. However, it is often associated with prolonged procedure times and frequently requires repeated interventions. A randomized controlled trial demonstrated that, compared with conventional stone extraction methods, electrohydraulic lithotripsy improved the endoscopic clearance rate for large bile duct stones although it increased the procedure time[9]. Similarly, a large international retrospective multicenter study of patients with difficult biliary stones undergoing electrohydraulic lithotripsy reported an overall success rate of 96.7%, a single-session clearance rate of 74.5%, and a mean procedure time of 73.9 minutes[10]. However, in Mirizzi syndrome, tenaciously impacted stones increase the difficulty of extraction, whereas a large stone size and relative biliary stenosis lead to prolonged lithotripsy time and an increased risk of residual stones.

Failure to address the biliary stricture not only hinders the passage of instruments but also prevents complete stone clearance. Plastic stents were easy to place and remove and could relieve biliary obstruction caused by stones, while providing limited improvement in distal bile duct strictures. Shirly et al[11] reported a method of treating type I Mirizzi syndrome using ERCP-guided plastic stent placement combined with cholecystectomy. Some researchers attempted to address distal stenosis by placing a fully covered stent in the bile duct, followed by stone extraction, although its potential risks include possible erosion of the duodenal wall, difficulty in repositioning or removal, and obstruction of the pancreatic duct by covered stents[12]. Mandai et al[13] reported successful biliary stone removal after fully covered metal stent placement for post-endoscopic sphincterotomy papillary stenosis. Another study reported that a fully covered self-expandable metallic stent used as a cystic duct overtube facilitated stone removal from the gallbladder[14]. Koksal et al[7] reported the use of fully covered self-expandable metal stent placement for the management of difficult biliary stones, achieving complete stone clearance in 90.9% (30/33) of the patients. Here, the success rate of secondary stone extraction after fully covered stent placement was 82.6%, and the median stone extraction time was 21.5 minutes. Three cases of pancreatitis were observed, potentially related to cannulation or stent implantation, comparable to the incidence reported in a previous study[15]. Additionally, 5 cases of cholecystitis occurred, which may be associated with Mirizzi syndrome. Thus, stone extraction after a fully covered stent is a viable option for Mirizzi syndrome, particularly for patients unsuitable for prolonged ERCP or those with marked distal bile duct stenosis, although individualized decision-making based on anatomy and operator expertise is essential. Notably, four patients in the present study still required electrohydraulic lithotripsy for stone removal after dilation with covered stents, suggesting that for large and hard stones, additional stone removal modalities may still be necessary in combination with covered stents.

This study is among the few to explore the endoscopic management of Mirizzi syndrome, but it has limitations: The cohort was small and heterogeneous, and its non-randomized, retrospective design may introduce bias related to variation in biliary anatomy and endoscopist experience. These findings should be interpreted cautiously, and further randomized trials are warranted to refine endoscopic strategies.

CONCLUSION

This is the first study, to our knowledge, on the feasibility and safety of stone extraction after fully covered stent placement in Mirizzi syndrome. These data underscore the need for further evaluation of this novel technique in large-scale, prospective, multicenter trials, preferably with the inclusion of a control group.

ACKNOWLEDGEMENTS

We thank the Endoscopy Center, Renji Hospital, for their support.