FISTULA-RFA Trial: Radiofrequency Ablation for Perianal Fistula (FISTULA-RFA)

March 1, 2026 updated by: Sunseok Yoon, Korea University Ansan Hospital

FISTULA-RFA Trial (Fistula Inactivation by Segmental Thermal Uniform Lesion Ablation-Radiofrequency Ablation): A Prospective, Multicenter, Single-Arm Pilot Study in Patients With Perianal Fistula

The goal of this pilot clinical study is to learn whether radiofrequency ablation (RFA) can safely and effectively treat perianal fistulas in adults. It will also evaluate procedure-related safety and changes in symptoms over time. The main questions it aims to answer are:

  • How many participants achieve fistula closure by 6 months after RFA treatment?
  • How often do fistulas recur during follow-up?
  • What medical problems or adverse events occur after the RFA procedure (for example, pain, bleeding, infection, urinary retention, or changes in continence)?
  • How do patient-reported outcomes (such as pain and quality of life) change after treatment? This is a prospective, multicenter, single-arm pilot study. All participants will receive RFA treatment; there is no comparison (control) group.

Participants will:

  • Be screened and enrolled at one of the participating hospitals
  • Undergo a standardized RFA procedure for the perianal fistula
  • Attend follow-up visits with clinical assessments at regular time points up to 6 months (including key assessments around 3 and 6 months)
  • Report symptoms and any adverse events during the follow-up period

Study Overview

Status

Not yet recruiting

Conditions

Intervention / Treatment

Detailed Description

Perianal fistula is a chronic inflammatory tract that can cause persistent discharge, pain, recurrent abscess formation, and substantial impairment in daily activities and quality of life. While definitive surgical management aims to eradicate the fistula while preserving sphincter function, conventional approaches may be limited by variable healing rates, risk of recurrence, and concerns regarding sphincter injury and subsequent continence disturbance-particularly in complex fistulas or in patients at higher risk of incontinence. As a result, sphincter-preserving, minimally invasive techniques have been actively explored to improve clinical outcomes while minimizing functional compromise.

Radiofrequency ablation (RFA) is a thermal energy-based modality that can induce controlled tissue coagulation and remodeling. For perianal fistula treatment, RFA has the potential to ablate the fistula tract internally and promote tract closure without dividing sphincter muscles. However, a key challenge in energy-based fistula treatments is achieving consistent and uniform ablation along the entire tract length, because uneven energy delivery may lead to insufficient ablation in certain segments and treatment failure or recurrence. To address this limitation, a novel, dedicated RFA fistula device has been developed to deliver thermal energy in a standardized manner along the tract, with the intent of achieving more uniform ablation across tract segments (ie, segment-by-segment energy delivery rather than focal "dot" ablation). Prior preclinical work using a porcine perianal fistula model was performed to establish feasible operating parameters and to support translation to a first-in-human clinical pilot study.

Objectives The primary objective of this prospective multicenter single-arm pilot study is to evaluate the clinical efficacy of a novel RFA device for the treatment of perianal fistula in adult participants, with clinical fistula closure assessed at 6 months after the procedure. Secondary objectives are to evaluate safety (procedure- and device-related adverse events), recurrence patterns during follow-up, and changes in symptom burden and functional outcomes over time. In addition, this pilot study aims to assess procedural feasibility and to generate data that will inform the design of larger confirmatory studies, including refinement of outcome definitions, follow-up strategy, and operational standardization across sites.

Methods This is a prospective, multicenter, single-arm pilot interventional study enrolling adult participants with perianal fistula who are considered appropriate for a sphincter-preserving approach. All enrolled participants will receive RFA treatment using the dedicated fistula RFA device under a standardized procedural framework across participating sites.

Intervention (RFA procedure):

RFA will be delivered intraluminally to the fistula tract using the dedicated RFA catheter introduced via the external opening according to the standardized technique. The procedure is designed to apply controlled thermal energy along the tract to promote tract closure while minimizing injury to surrounding sphincter structures. Periprocedural management and post-procedure care will follow a harmonized protocol across sites to support consistent implementation and safety monitoring.

Follow-up and assessments:

Participants will be evaluated longitudinally after the procedure, with key clinical assessments at approximately 3 and 6 months post-procedure (in addition to immediate post-procedure assessment per routine clinical care). Clinical evaluation will include inspection and digital rectal examination to assess fistula healing status and to identify any signs of persistent or recurrent disease. Safety monitoring will include collection and documentation of adverse events from the time of the procedure through the final follow-up assessment, including severity and relationship to the procedure/device. Patient-reported symptoms (including pain) and functional outcomes (including continence-related measures and quality-of-life measures when applicable) will be captured at predefined time points.

Endpoints overview:

The primary endpoint is clinical fistula closure at 6 months after RFA treatment, based on standardized clinical criteria. Secondary endpoints include recurrence during follow-up, safety outcomes (adverse events/serious adverse events), symptom trajectories (eg, pain), functional outcomes (eg, continence), quality of life measures, and the need for additional fistula-related interventions.

Data analysis:

As a pilot study, analyses will primarily be descriptive and estimation-focused to characterize preliminary efficacy and safety signals. Outcome measures will be summarized using appropriate descriptive statistics, and clinically relevant proportions (eg, closure and recurrence rates) will be reported with confidence intervals where applicable. The resulting data will be used to inform sample size assumptions, endpoint operationalization, and protocol optimization for subsequent larger-scale studies.

Study Type

Interventional

Enrollment (Estimated)

80

Phase

  • Not Applicable

Contacts and Locations

This section provides the contact details for those conducting the study, and information on where this study is being conducted.

Study Contact

  • Name: Kwang Dae Hong, MD, PhD, Professor
  • Phone Number: +82-031-412-4380
  • Email: drhkd@korea.ac.kr

Study Contact Backup

  • Name: Korea University Ansan Hospital IRB Desk
  • Phone Number: +82-031-412-6520

Participation Criteria

Researchers look for people who fit a certain description, called eligibility criteria. Some examples of these criteria are a person's general health condition or prior treatments.

Eligibility Criteria

Ages Eligible for Study

  • Adult
  • Older Adult

Accepts Healthy Volunteers

No

Description

Inclusion Criteria:

  • Adults aged 20 to 74 years
  • Able and willing to provide written informed consent after receiving explanation of the study purpose, procedures, potential benefits, and risks

  • Diagnosed with one or more of the following perianal fistula types:

    1. High trans-sphincteric fistula
    2. Low trans-sphincteric fistula with high risk of fecal incontinence (sphincter injury risk)
    3. Fistula with seton placement (seton in situ or previously placed per protocol)
    4. Crohn's disease-associated perianal fistula
    5. Complex fistula, including cases with a history of perineal or gynecologic surgery and/or recurrent fistula

Exclusion Criteria:

  • Superficial fistula that is expected to be curable with simple fistulotomy with minimal risk of sphincter injury
  • Fistula related to malignancy
  • Any contraindication to RFA, including: History of stapled hemorrhoidopexy, Presence of endoscopic clips (or similar metallic clips) within the anal canal, Fecal diversion with stoma (diverting stoma in place), Pregnancy

Study Plan

This section provides details of the study plan, including how the study is designed and what the study is measuring.

How is the study designed?

Design Details

  • Primary Purpose: Treatment
  • Allocation: N/A
  • Interventional Model: Single Group Assignment
  • Masking: None (Open Label)

Arms and Interventions

Participant Group / Arm
Intervention / Treatment
Experimental: Radiofrequency Ablation (RFA) Treatment Arm
Participants in this single-arm, prospective multicenter pilot study will undergo radiofrequency ablation (RFA) for treatment of perianal fistula using a standardized procedural protocol across sites. Clinical outcomes and safety will be assessed longitudinally through follow-up, with the primary clinical assessment at 6 months after the procedure.
Device: Radiofrequency Ablation (RFA) for Perianal Fistula
Radiofrequency ablation (RFA) will be delivered to the fistula tract using a dedicated RFA catheter introduced through the external opening under standardized technique. The procedure aims to apply controlled thermal energy along the tract to promote tract closure while minimizing injury to surrounding sphincter structures. Participants will receive a single RFA treatment per protocol, with post-procedure care and safety monitoring during scheduled follow-up.

What is the study measuring?

Primary Outcome Measures

Outcome Measure
Measure Description
Time Frame
Fistula Closure (Clinical Healing)
Time Frame: Baseline(post-procedure) and at 3 and 6 months after RFA
Fistula closure will be determined by clinical assessment, defined as: (1) complete epithelialization/absence of the external opening on inspection, (2) no drainage/discharge (spontaneous or on gentle pressure), and (3) no clinically apparent fistula tract opening on digital rectal examination (DRE). Symptom improvement (including reduced pain) will be recorded as supportive patient-reported information.
Baseline(post-procedure) and at 3 and 6 months after RFA

Secondary Outcome Measures

Outcome Measure
Measure Description
Time Frame
Fistula Recurrence
Time Frame: Up to 6 months after RFA (assessed at 3 and 6 months)
Recurrence after initial clinical closure, defined as reappearance of an external opening, recurrent drainage/discharge, or clinical evidence of a fistula tract on examination during follow-up.
Up to 6 months after RFA (assessed at 3 and 6 months)
Time to Fistula Closure
Time Frame: Up to 6 months after RFA
Time from the RFA procedure to first documented clinical closure as defined in the primary outcome criteria.
Up to 6 months after RFA
Incidence of Adverse Events (AEs) and Serious Adverse Events (SAEs)
Time Frame: From the day of procedure through 6 months after RFA
Number and proportion of participants experiencing procedure- or device-related AEs/SAEs (eg, bleeding, infection/abscess, urinary retention, severe pain requiring intervention, hospitalization, or reoperation), graded by severity and relationship to the procedure/device.
From the day of procedure through 6 months after RFA
Change in Pain Severity
Time Frame: Baseline (pre-procedure), 3 months, and 6 months after RFA
Change in patient-reported pain interference compared with baseline, assessed using the PROMIS® Pain Interference - Short Form 8a. The instrument includes 8 items, each scored on a 5-point Likert scale (1=not at all to 5=very much). Item scores are summed to generate a raw total score ranging from 8 to 40, with higher scores indicating worse pain interference. The outcome will be reported as the change in raw total score from baseline at each follow-up time point.
Baseline (pre-procedure), 3 months, and 6 months after RFA
Change in Fecal Continence
Time Frame: Baseline, 3 months, and 6 months after RFA
Change in continence status assessed by a validated score (Wexner/St. Mark's incontinence score), compared with baseline.
Baseline, 3 months, and 6 months after RFA
Change in Health-Related Quality of Life
Time Frame: Baseline, 3 months, and 6 months after RFA
Change in quality of life using a validated patient-reported measure (PROMIS), compared with baseline.
Baseline, 3 months, and 6 months after RFA
Need for Additional Fistula-Related Intervention
Time Frame: Up to 6 months after RFA
Proportion of participants requiring additional fistula-related procedures or treatments during follow-up (eg, drainage, seton placement, repeat ablation, or surgery).
Up to 6 months after RFA

Other Outcome Measures

Outcome Measure
Measure Description
Time Frame
Patient Global Impression of Improvement (PGI-I)
Time Frame: 3 months and 6 months after RFA
Patient-reported global improvement using a single-item global rating (PGI-I)
3 months and 6 months after RFA
Procedural Feasibility and Technical Success
Time Frame: During the procedure (day of RFA)
Successful completion of the planned RFA procedure per protocol (eg, ability to access the tract and deliver energy as intended) without intra-procedural device failure.
During the procedure (day of RFA)
Procedure Duration
Time Frame: Day of procedure
Procedure duration, defined as the time recorded in the operative report from the start of the fistula procedure to completion (minutes).
Day of procedure
Same-day Discharge
Time Frame: Day of procedure (post-procedure day 0)
Proportion of participants discharged on the day of the procedure (post-procedure day 0), recorded as Yes/No.
Day of procedure (post-procedure day 0)
Time to Return to Normal Activity
Time Frame: Up to 30 days after RFA procedure
Time (days) from the procedure to return to usual/normal daily activities, as reported by the participant.
Up to 30 days after RFA procedure

Collaborators and Investigators

This is where you will find people and organizations involved with this study.

Sponsor

Korea University Ansan Hospital

Investigators

  • Study Chair: Kwang Dae Hong, MD, PhD, Professor, Department of Colorectal Surgery, Korea University Ansan Hospital

Publications and helpful links

The person responsible for entering information about the study voluntarily provides these publications. These may be about anything related to the study.

General Publications

Study record dates

These dates track the progress of study record and summary results submissions to ClinicalTrials.gov. Study records and reported results are reviewed by the National Library of Medicine (NLM) to make sure they meet specific quality control standards before being posted on the public website.

Study Major Dates

Study Start (Estimated)

April 1, 2026

Primary Completion (Estimated)

January 30, 2027

Study Completion (Estimated)

August 30, 2027

Study Registration Dates

First Submitted

February 11, 2026

First Submitted That Met QC Criteria

March 1, 2026

First Posted (Actual)

March 5, 2026

Study Record Updates

Last Update Posted (Actual)

March 5, 2026

Last Update Submitted That Met QC Criteria

March 1, 2026

Last Verified

February 1, 2026

More Information

Terms related to this study

Keywords

Additional Relevant MeSH Terms

Other Study ID Numbers

  • 2025AS0310

Plan for Individual participant data (IPD)

Plan to Share Individual Participant Data (IPD)?

UNDECIDED

Drug and device information, study documents

Studies a U.S. FDA-regulated drug product

No

Studies a U.S. FDA-regulated device product

No

This information was retrieved directly from the website clinicaltrials.gov without any changes. If you have any requests to change, remove or update your study details, please contact register@clinicaltrials.gov. As soon as a change is implemented on clinicaltrials.gov, this will be updated automatically on our website as well.

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