An interventional study of Laser ablation of fistula tract using 1000-µm radial fibre (Biolitec, 1470 nm, 12 W, continuous, 1 mm/s withdrawal). Internal opening closed with Vicryl 2/0 suture in all patients in Perianal Fistula, sponsored by Complejo Hospitalario Universitario de Santiago. Not yet recruiting. Open to participants aged Up to 18 Years. Per ClinicalTrials.gov, last updated 2026-09-09.
Sponsored by Complejo Hospitalario Universitario de Santiago · Not applicable, Interventional, and Treatment
Multi-recurrent cryptoglandular perianal fistula represents a challenging clinical problem with no established surgical solution after repeated failures. This pilot study evaluates the combination of fistula-tract laser closure (FiLaC) with perilesional injection of autologous platelet-rich growth factor (PRGF-Endoret) in 25 patients with a long-standing seton and no active sepsis. The primary outcome is clinical cure at 12 months. This study will provide preliminary safety and efficacy data to inform the design of a future randomised trial
Background
Perianal fistula is a benign but recurrent condition that causes significant morbidity. A subgroup of patients experiences repeated recurrence despite multiple surgical interventions, resulting in progressive fibrosis of the perianal tissue and increasing risk of sphincter damage with each reoperation. No sphincter-preserving technique consistently achieves cure after multiple surgical failures.
Fistula-tract laser closure (FiLaC) uses a radially emitting diode laser probe to achieve thermal ablation of the fistula tract epithelium. Its principal demonstrated advantage is an exceptional continence safety profile, with no cases of continence deterioration reported in large published series. However, failure rates exceed 40%, leaving a substantial proportion of patients without a definitive solution.
Platelet-rich growth factor (PRGF-Endoret; BTI Biotechnology Institute, Vitoria, Spain) is a fully autologous biological product obtained from the patient's own peripheral blood by low-speed centrifugation, free of leucocytes and exogenous activators. It releases a sustained supply of tissue repair growth factors that promote neoangiogenesis, fibroblast proliferation, and extracellular matrix remodelling. Prior studies combining platelet-rich plasma with surgical techniques for perianal fistula have reported improved clinical healing rates compared to surgery alone. The specific combination of FiLaC laser ablation with perilesional PRGF injection has not been previously evaluated.
Rationale The biological rationale for the PLASMA procedure is synergistic. Laser ablation removes the fistula tract epithelium and creates a receptive tissue bed. Immediate perilesional PRGF injection provides the growth factors required to accelerate healing and reduce the chronic inflammation that drives recurrence in multi-operated fistulas. Mandatory closure of the internal opening eliminates the high-pressure intestinal entry point that perpetuates the fistula. Selection of patients with a seton in situ for at least 6 months without active sepsis ensures a quiescent tissue microenvironment at the time of treatment.
Procedure All procedures are performed by a single surgeon under spinal anaesthesia as ambulatory day surgery. The PLASMA procedure consists of four sequential steps in a single operative session: (1) seton removal; (2) fistula tract laser ablation using a 1000-µm radially emitting FiLaC probe connected to a Leonardo Dual diode laser (1470 nm, 12 W, continuous mode, 1 mm/s withdrawal speed); (3) mandatory direct primary suture closure of the internal opening (Vicryl 2/0) in all patients; (4) perilesional injection of 7 ml of activated autologous PRGF-Endoret around the fistula tract and closure site using a 23-gauge needle under direct vision.
PRGF-Endoret is prepared on the day of surgery from 36 ml of peripheral venous blood collected in four sodium citrate tubes, centrifuged at 580 rpm for 8 minutes. The leucocyte-free platelet-rich fraction is activated with autologous calcium chloride solution immediately before injection. PRGF-Endoret has been authorised as a Sustancia de Origen Humano (SoHo) for use in this study by the Organizacion Nacional de Trasplantes (ONT) of Spain.
Statistical approach This is a descriptive pilot study. The primary endpoint will be expressed as a proportion with exact 95% confidence interval. Continence and quality of life scores will be compared between baseline and follow-up timepoints using the Wilcoxon signed-rank test for paired samples. Factors associated with clinical cure will be explored by exploratory post hoc univariate analysis. No multivariate analysis is planned. All results are hypothesis-generating and will not be interpreted as confirmatory evidence. Analyses will be performed in Python 3.12
219 studies on the registry are indexed under Fistula; 49 are open to participants now.
This study's planned enrollment of 25 is below the median of 50 across 152 interventional studies indexed under Fistula.
Browse Fistula studies →Complejo Hospitalario Universitario de Santiago is the lead sponsor of 2 studies on the registry; 2 are open to participants now.
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Exclusion Criteria:
Underlined terms in the criteria open these too. Explained by clinicaltrials.gg, not part of the registry record. The study team decides who can take part.
Blood cells that help blood clot. Too few raises the risk of bleeding and bruising. A usual adult range is about 150–400 × 10⁹/L (150,000–400,000 per µL); each lab has its own reference range.
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Malignancy means cancer. Criteria about another or earlier malignancy ask whether you have had a different cancer, usually within a set number of years.
Some are commonly allowed, such as treated skin cancers other than melanoma and early cancers removed completely — check the exceptions this study lists.
A weakened immune system. It can come from an illness, such as HIV or some blood cancers, or from medicines that turn the immune system down, for example after an organ transplant or for an autoimmune disease; steroids at higher doses count.
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Platelets
Blood cells that help blood clot. Too few raises the risk of bleeding and bruising. A usual adult range is about 150–400 × 10⁹/L (150,000–400,000 per µL); each lab has its own reference range.
Explained by clinicaltrials.gg, not part of the registry record. The study team decides who can take part.
Informed consent
Before you join, the study team explains what taking part involves — its purpose, what happens, the risks and possible benefits — and answers your questions, so you can decide freely. Consent is usually recorded on a form (the informed consent form, ICF) signed by you or, where the law allows, by someone legally authorised to decide for you.
You can keep asking questions during the study, you are told of new information that matters, and you can choose to leave at any time.
Explained by clinicaltrials.gg, not part of the registry record. The study team decides who can take part.
Cancer (malignancy)
Malignancy means cancer. Criteria about another or earlier malignancy ask whether you have had a different cancer, usually within a set number of years.
Some are commonly allowed, such as treated skin cancers other than melanoma and early cancers removed completely — check the exceptions this study lists.
Explained by clinicaltrials.gg, not part of the registry record. The study team decides who can take part.
Immunosuppression
A weakened immune system. It can come from an illness, such as HIV or some blood cancers, or from medicines that turn the immune system down, for example after an organ transplant or for an autoimmune disease; steroids at higher doses count.
Read whether the line is about a condition or about medicines, and which medicines and doses it means.
Explained by clinicaltrials.gg, not part of the registry record. The study team decides who can take part.
Single ambulatory procedure under spinal anaesthesia: seton removal, FiLaC laser ablation (1470 nm, 12 W, 1 mm/s), direct primary suture closure of internal opening (Vicryl 2/0), perilesional injection of 7 ml autologous PRGF-Endoret. Intervention.
Procedure: Laser ablation of fistula tract using 1000-µm radial fibre (Biolitec, 1470 nm, 12 W, continuous, 1 mm/s withdrawal). Internal opening closed with Vicryl 2/0 suture in all patients
Perilesional injection of 7 ml of autologous platelet-rich growth factor (PRGF-Endoret; BTI Biotechnology Institute, Vitoria, Spain), prepared from 36 ml of peripheral venous blood collected in four 9-ml sodium citrate tubes, centrifuged at 580 rpm for 8 minutes. The platelet-rich fraction, free of leucocytes and erythrocytes, is activated with autologous calcium chloride solution (0.05 ml of CaCl₂ 10% per ml of PRGF) immediately before injection and administered perilesionally around the fistula tract and internal opening closure site using a 23-gauge needle under direct vision.
Measure: Clinical cure at 12 months
Complete closure of the external opening without spontaneous or compression-induced drainage on clinical examination
Time frame: 12 months after the procedure
Incidence of Postoperative Complications Classified by Clavien-Dindo Grade [Safety]
Any postoperative complication within 30 days classified by Clavien-Dindo system: Grade I = minor deviation requiring no treatment; Grade II = pharmacological treatment; Grade III = surgical/endoscopic/radiological intervention; Grade IV = organ dysfunction; Grade V = death). Proportion with Grade III or above reported separately.
Time frame: 30 days after the procedure
Clinical cure at 6 months
Complete closure of the external opening without spontaneous or compression-induced drainage on clinical examination at 6 months after the procedure.
Time frame: 6 months
Change in Faecal Continence Assessed by Wexner Continence Grading Scale
Wexner Continence Grading Scale (range 0-20; 0 = perfect continence, 20 = complete incontinence; lower scores indicate better continence). Change from baseline to each timepoint reported.
Time frame: Baseline (preoperative), 3, 6, and 12 months after the procedure
Postoperative Pain Assessed by Visual Analogue Scale
Visual Analogue Scale for pain (range 0-10 cm; 0 = no pain, 10 = worst imaginable pain; lower scores indicate less pain)..
Time frame: 24 hours, 48 hours, 7 days, and 1 month after the procedure
Fistula recurrence | 12 months • New surgical intervention
Reopening of a previously healed external orifice with drainage after documented clinical cure at any prior follow-up visit.
Time frame: 12 months
No study locations are listed for this record.
Plan to share: No — Individual participant data will not be shared publicly. Data are pseudonymised and stored under applicable Spanish and European data protection legislation (GDPR / Ley Orgánica 3/2018). Anonymised aggregate data supporting the published findings may be available upon reasonable request to the corresponding author, subject to ethics committee approval.
Start is estimated for Oct 2026; primary completion for Dec 2028, 26 months later.
Of 45 non-industry interventional studies with no phase under Fistula, half reached primary completion within 26 months of starting (the median), counting those still running; a quarter within 15 and three quarters within 56. This study's planned 26 months is close to that.
Counting every sponsor, half of 51 studies reached it within 23 months; a quarter within 14 and three quarters within 52.
How these figures are worked out, and which studies are left out of them.
This study is not yet recruiting, as verified in Aug 2026. You cannot join it, but the record below documents what was studied.
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Complejo Hospitalario Universitario de Santiago