Endoscopic Radiofrequency Ablation Combined with Metal Stent Placement for Malignant Biliary Stricture

Summary

This protocol details endoscopic RFA combined with metal stent placement for unresectable malignant biliary strictures, aiming to standardize the minimally invasive procedure and guide its clinical application to improve biliary patency and patient outcomes.

Abstract

Malignant biliary strictures (MBS) are a challenging clinical issue with limited therapeutic options for unresectable cases. This protocol establishes a standardized minimally invasive approach of endoscopically-guided biliary radiofrequency ablation (RFA) combined with self-expandable metal stent (SEMS) placement via endoscopic retrograde cholangiopancreatography (ERCP) for MBS. The core workflow includes preoperative preparation, endoscopic exploration and cholangiography, direct cholangioscopic assessment, targeted RFA of the stenotic segment, SEMS deployment, and postoperative management and follow-up. Key procedural parameters are defined: bipolar RFA at 8 W for 90–120 s, and placement of a covered SEMS (CSEMS) with 1 cm extension beyond the stenosis margins. Clinical application in a representative case achieved rapid resolution of jaundice (70% reduction in total bilirubin at 5 days post-procedure) and technical success with unobstructed biliary patency at 1 month. The procedure has a favorable safety profile, with no major acute complications observed in the case. This standardized protocol provides a reproducible method for clinical practitioners, and the combined technique offers a valuable palliative option for unresectable MBS by prolonging stent patency and alleviating biliary obstruction symptoms. Further multicenter trials are needed to validate its long-term efficacy in larger patient cohorts.

Introduction

Malignant biliary strictures (MBS) are caused by primary or secondary tumors and are characterized by insidious onset and rapid progression, resulting in most patients being diagnosed at an advanced, unresectable stage¹. Surgical resection remains the only curative treatment option but is feasible in only 10%–40% of patients with cholangiocarcinoma, with a median survival of less than 24 months². Systemic therapies, including chemotherapy, radiotherapy, and immunotherapy, frequently demonstrate limited efficacy because of the complex tumor microenvironment and high genetic heterogeneity of biliopancreatic malignancies³. Progressive biliary obstruction can lead to severe biliary infection, obstructive jaundice, and liver failure, significantly impairing quality of life and survival outcomes, thereby making palliative biliary drainage an essential component of clinical management⁴. Endoscopic stent placement is considered the first-line palliative drainage strategy; however, approximately 30% of patients experience stent occlusion within 3 months, leading to recurrent cholangitis and repeated interventions⁵. Endobiliary radiofrequency ablation (RFA) has emerged as an important adjunctive treatment modality. By delivering thermal energy at 80–100 °C, RFA induces tumor coagulative necrosis, occludes tumor-feeding vessels, and stimulates anti-tumor immune responses^6,7,8. Combined application of RFA and stent placement has been shown to prolong both stent patency and overall survival in patients with unresectable MBS. A 2023 meta-analysis demonstrated that RFA combined with stenting increased median survival by 2.88 months and extended stent patency by 2.11 months compared with stenting alone, without increasing the incidence of adverse events^9,10.

Stent selection is a critical determinant of long-term therapeutic efficacy. Plastic stents are susceptible to sludge-related occlusion, covered self-expandable metal stents (CSEMS) may be associated with food reflux and migration, and uncovered self-expandable metal stents (USEMS) remain vulnerable to tumor ingrowth¹¹. Compared with plastic stents, metal stents provide superior drainage efficiency and longer patency in patients with extrahepatic cholangiocarcinoma and are therefore preferred for individuals with an expected survival exceeding 3 months. Endoscopic retrograde cholangiopancreatography (ERCP) and percutaneous transhepatic cholangiopancreatography (PTCD) represent the two principal approaches for combining RFA with biliary stenting. ERCP is generally recommended as the first-line approach because it is associated with improved long-term survival, whereas PTCD is reserved for patients with ERCP failure or complex anatomical conditions such as Bismuth-Corlett type IV hilar cholangiocarcinoma^12,13. Appropriate patient selection is essential for procedural safety and efficacy. Suitable candidates include patients with unresectable intrahepatic or extrahepatic MBS, an expected survival greater than 3 months, tolerance for ERCP, and focal biliary strictures without diffuse mucosal invasion^14,15. Patients with severe coagulopathy, uncontrolled acute cholangitis, diffuse biliary involvement, major vascular invasion, or contraindications to sedation are generally excluded from treatment^14,15.

This study presents a standardized protocol for ERCP-guided RFA combined with CSEMS placement in patients with unresectable MBS. The protocol establishes a reproducible workflow designed to achieve effective local tumor control while maintaining sustained biliary drainage. The manuscript further describes the complete procedural sequence, critical technical parameters, and safety precautions required for safe and consistent clinical implementation. A representative clinical case involved a 73-year-old male patient without a history of diabetes, hypertension, or coagulation dysfunction. The patient was diagnosed with gallbladder cancer in February 2024 and subsequently underwent laparoscopic cholecystectomy, hepatic lymph node dissection, segmental liver resection (S4b and S5), and partial transverse colon resection in March 2024. Postoperative pathology confirmed stage IIIa gallbladder carcinoma (pT3N0M0). The patient later received three cycles of adjuvant oral chemotherapy with tegafur-gimeracil potassium (S-1, 40 mg twice daily). In March 2025, the patient developed painless jaundice of one-week duration and underwent ERCP with plastic biliary stent placement; however, recurrent jaundice developed within two weeks, necessitating readmission. Physical examination revealed scleral and cutaneous jaundice without abdominal tenderness, rebound tenderness, hepatosplenomegaly, or a positive Murphy’s sign. Contrast-enhanced computed tomography demonstrated thickening of the duodenojejunal common bile duct wall with proximal biliary dilatation (Figure 1A), while magnetic resonance cholangiopancreatography showed proximal dilation of the intrahepatic and common bile ducts with mid-luminal stenosis and a suspected filling defect (Figure 1B). Laboratory evaluation revealed elevated total bilirubin (219.4 µmol/L), direct bilirubin (156.7 µmol/L), alanine aminotransferase (189 U/L), and aspartate aminotransferase (126 U/L), with normal coagulation function (INR 1.05). Based on imaging findings, laboratory results, and clinical history, the patient was diagnosed with postoperative biliary metastasis of gallbladder cancer, causing an unresectable extrahepatic malignant biliary stricture with obstructive jaundice. Benign biliary strictures and other metastatic tumors were excluded through comprehensive clinical and radiological evaluation. Considering the unresectable status, preserved general condition, and expected survival exceeding 3 months, ERCP-guided RFA combined with CSEMS placement was selected to ablate local tumor tissue, maintain biliary patency, and relieve jaundice. Standalone stent placement was not considered appropriate because of the rapid occlusion of the previously placed plastic stent. Potential complications, including pancreatitis, cholangitis, bleeding, and biliary perforation, were anticipated, and prophylactic antibiotics together with close postoperative monitoring were planned to minimize procedural risks.

Protocol

All procedures were performed in accordance with the 1964 Declaration of Helsinki and its later amendments. Written informed consent was obtained from the patient before all interventions. The reagents and the equipment used are listed in the Table of Materials.

1. Preoperative preparation

1. Patient position: Position the patient in the left lateral or prone decubitus position, with the head tilted to the right to facilitate endoscopic insertion.
2. Anesthesia method: Administer deep intravenous sedation with endotracheal intubation general anesthesia to ensure analgesia, amnesia, and muscle relaxation.
   1. Inject fentanyl 2–4 µg/kg intravenously for anesthesia induction.
   2. Inject propofol 1.5–2.5 mg/kg intravenously for sedation and loss of consciousness.
   3. Inject cis-atracurium 0.15 mg/kg intravenously for muscle relaxation prior to tracheal intubation.
   4. To maintain anesthesia, use 0.5%–1% sevoflurane, and combine with continuous infusion of propofol (4–8 mg/(kg·h)) + remifentanil at 0.15–0.7µg/kg via intravenous pump, keeping the BIS (Bispectral Index) within the 40–60 range.
3. Instrument and consumable preparation
   1. Prepare the following equipment: duodenoscope, standard ERCP accessories (0.035-inch hydrophilic guidewire, ERCP cannula, sphincterotome), single-use video cholangioscope, biliary radiofrequency ablation catheter, RFA generator, and covered biliary self-expandable metal stent (CSEMS).
      NOTE: Verify the functionality of all electronic devices (RFA generator, ablation catheter, endoscopy system) before the procedure.

2. Endoscopic exploration and cannulation

1. Duodenoscopy: Insert a duodenoscope through the mouth to the descending duodenum, and observe the morphology of the duodenal papilla (Figure 2A).
2. Remove the pre-existing plastic stent: Grasp the distal end of the indwelling plastic stent using foreign-body forceps. Gently retract the stent to remove it completely from the biliary tract.
3. Selective biliary catheterization: Perform selective biliary cannulation via the major papilla using a sphincterotome loaded with a 0.035-inch biliary guidewire. Adjust the direction and axis to advance the guidewire selectively into the left intrahepatic bile duct. Aspirate approximately 5 mL of bile for laboratory analysis.
4. Cholangiography: Inject 5 mL of iohexol contrast medium (mixed with gentamicin) under fluoroscopic guidance to obtain a cholangiogram (Figure 2B).
   NOTE: Avoid excessive injection of contrast agent to prevent biliary pressure elevation and cholangitis.

3. Cholangiography and stenosis assessment

1. Observe the cholangiographic images under fluoroscopy to clearly identify the location, length, and degree of biliary stricture, and assess the extent of proximal biliary dilation. Record all imaging findings for procedural planning (Figure 3).

4. Direct cholangioscopic assessment

1. Cholangioscope insertion: Advance the cholangioscope over the guidewire into the bile duct lumen. Proceed to the stenotic segment under direct visualization (Figure 4).
2. Visual evaluation and biopsy: Inspect mucosal texture, vascular proliferation, and bleeding tendency. Obtain 3–4 tissue samples from the most stenotic area using biopsy forceps (Video 1).
   NOTE: Avoid excessive biopsies to prevent severe bleeding or biliary perforation in the tumor-infiltrated segment.

5. Radiofrequency ablation (RFA) procedure

1. RFA catheter placement
   1. Withdraw the cholangioscope. Advance the bipolar RFA catheter over the guidewire into the stenotic segment. Confirm that the electrode segment fully spans the entire stenosis under fluoroscopic guidance (Figure 5).
2. Ablation parameter setting
   1. Set the RFA generator to bipolar soft-mode. Configure energy at 8 W and ablation duration at 90–120 s.
3. Ablation execution
   1. Activate the RFA generator after confirming a stable catheter position. Deliver ablation for 90 s, then withdraw the catheter slowly and uniformly to ensure full coverage of the stenotic segment.
4. Procedural safeguards to avoid thermal injury
   1. Limit ablation strictly to the tumor-involved stricture segment. Avoid direct contact between the RFA electrode and normal bile duct mucosa or vessel-rich peritumoral tissue to prevent excessive thermal damage, bleeding, or bile duct perforation¹⁴.
   2. Maintain stable guidewire positioning and perform gentle catheter manipulation throughout energy delivery to prevent unintended electrode migration¹⁶.
5. Intra-procedural monitoring
   1. Continuously monitor heart rate, blood pressure, and oxygen saturation. Use cholangioscopy to assess mucosal vascularity, bleeding tendency, and tissue charring.
   2. Repeatedly use fluoroscopy to verify catheter alignment and avoid unintended contact with adjacent vessels or organs¹⁷.
6. Criteria for early termination of ablation: Stop ablation immediately if any of the following occurs¹⁸:
   1. Observe new-onset sustained bleeding from the ablation site.
   2. Observe significant mucosal charring, bubbling, or tissue disruption.
   3. Detect sudden hypotension, arrhythmia, or other hemodynamic instability.
   4. Observe severe abdominal pain or patient intolerance despite adequate anesthesia.
   5. Suspect bile duct perforation or contrast extravasation under fluoroscopy.
      NOTE: Pause the procedure immediately if the patient shows signs of hemodynamic instability or severe abdominal pain during ablation.

6. Post-ablation choledochoscopic re-observation

1. Second-look cholangioscopy: Reinsert the cholangioscope over the guidewire to the ablated segment. Inspect mucosal status, luminal patency, and absence of active bleeding or perforation. Confirm adequate ablation before stent placement (Video 2).

7. Covered Self-Expandable Metal Stent (CSEMS) placement

1. Stent selection: Select a biliary covered Self-Expandable Metal Stent (CSEMS) with a diameter of 6 mm and a length of 80 mm.
2. Stent positioning and deployment: Insert the CSEMS delivery system along the guidewire into the bile duct. Position the stent so that both ends extend at least 1 cm beyond the proximal and distal margins of the stenosis, as confirmed under DSA fluoroscopy. Slowly release the stent to ensure full expansion and complete coverage of the stenosis (Figure 6).
   NOTE: Confirm stent position and expansion before withdrawing the delivery system to avoid stent migration.

8. Postoperative management and precautions

1. Monitor the patient’s vital signs (blood pressure, heart rate, body temperature) continuously for 24 h postoperatively. Test blood routine and blood amylase at 3 h, 6 h, and 12 h postoperatively, and test liver function at 24 h and 72 h postoperatively. Observe for clinical symptoms including abdominal pain, abdominal distension, black stool, and hematemesis.
2. Antibiotic prophylaxis: Administer broad-spectrum antibiotics intravenously (e.g., third-generation cephalosporins) to prevent cholangitis.

9. Follow-up plan

1. Perform liver function tests and abdominal ultrasound 1 month postoperatively to assess stent patency and biliary dilation. Perform MRCP or upper abdominal contrast-enhanced CT every 3 months postoperatively to monitor tumor progression and stent position/patency.
2. Record all adverse events (e.g., stent occlusion, cholangitis, pancreatitis) and reintervention measures during follow-up.

Results

This protocol integrates ERCP, cholangioscopic direct assessment, targeted RFA, and CSEMS placement into a complete diagnosis-ablation-drainage workflow, establishing a standardized minimally invasive treatment model for unresectable MBS.

The technique achieved technical success and favorable short-term clinical outcomes in the representative case, with clear procedural and clinical metrics that validate the reproducibility and efficacy of the method. Below is a detailed analysis of the proced...

Discussion

This protocol details a standardized ERCP-guided RFA combined with CSEMS placement technique for unresectable MBS, with a focus on procedural reproducibility, key technical steps, and clinical safety. The representative case validates the technical feasibility and short-term efficacy of the method, and the following discussion addresses critical procedural steps, troubleshooting strategies, technical limitations, and the clinical significance of the technique, aligned with the methods-focused requirements of a JoVE publi...

Materials

List of materials used in this article

Name	Company	Catalog Number	Comments
Biliary radiofrequency ablation catheter:Habib EndoHPB bipolar electrode	Boston Scientific	M00500070	The working area is composed of two stainless steel electrodes with a length of 8mm and an interval of 8mm, with a total length of 180cm and a diameter of 8fr, suitable for 0.035 guidewire.
Biliary self-expanding metal stents	Micro-Tech Medical (Nanjing)	BDS-Z-6/80-3/1800-A	Cemented stent, diameter 6mm,Length: 80 cm
Disposable Sphincterotome	Olympus	KD-V411M-0725
duodenoscope	Olympus	TJF-260V
guidewire	Olympus	G-260-2545S/G-260-3545S	0.035/0.025 inch hydrophilic guidewire
radio frequency generator	ERBE Elektromedizin GmbH	VIO 200
Single-use Video Pancreaticobiliary Scope:eyeMax	Micro-Tech Medical (Nanjing) Co., Ltd	CDS22001