Endoureteral ablation: A novel technique to occlude the ureter in patients with urinary tract fistulae

Abstract

Urinary fistulae are abnormal connections between the urinary system and adjacent body parts, often resulting from factors such as infection, radiation, malignancy, protracted labor, gynecologic surgery, and gastrointestinal tract surgery. These fistulae can lead to persistent urinary incontinence, skin breakdown, social humiliation, psychosocial trauma, and severe infections. Current treatments include surgical repair, urinary diversion, and ureteral embolization, though these can have complications and are not always successful or feasible for all patients. This manuscript proposes a novel approach to correcting urinary fistulae: Endoureteral ablation using laser or radiofrequency ablation. These techniques, known for treating various conditions, show promise in causing fibrosis to occlude fistulae. Early success in animal and human models suggests endoureteral ablation as a potentially more effective, less invasive, and cost-effective alternative to current methods, especially for patients unfit for surgery. However, further studies are needed to establish its viability and effectiveness.

Key Words: Urinary fistula; Radiofrequency ablation; Ureteral embolization; Laser ablation; Endoureteral ablation

Core Tip: Endoureteral ablation using laser or radiofrequency ablation presents a promising new treatment for urinary fistulae, converting energy to heat to induce fibrosis and occlude fistulas. Early successes in both animal and human models indicate that this method could offer a less invasive, more effective, and cost-efficient alternative to current treatments, particularly benefiting patients unfit for surgery. Further research is needed to confirm these findings and establish endoureteral ablation as a viable clinical option.

INTRODUCTION

Urinary fistulae are pathological connections between any component of the urinary system and an adjacent part of the body; examples include vesicouterine, ureteroarterial, vesicovaginal, and colovesical fistulae, just to name a few. Fistulae often result from factors such as infection, radiation, malignancy, protracted labor, gynecologic surgery, and surgery within the gastrointestinal tract[1-3]. Protracted labor is the primary cause, affecting millions of women globally[4]. Untreated, these fistulae can lead to persistent urinary incontinence, causing skin breakdown, social humiliation, and psychosocial trauma, and may also predispose individuals to infections, sepsis, and ultimately death[5,6].

ENDOURETERAL ABLATION

Current treatment options for urinary fistulae include surgical intervention and minimally invasive techniques of urinary diversion and ureteral embolization. Primary surgical repair has an approximate 80%-90% efficacy, although multiple surgeries may be necessary; in 10% of patients, complete fistula closure is unachievable[5,6]. Although surgical repair is often successful, many patients are not surgical candidates due to advanced disease and/or comorbidities. In such patients, interventional radiologists can divert urine from the fistulous tract by placing a percutaneous nephrostomy (PCN) tube. In cases refractory to urinary diversion in these patients, the ureter can be embolized by administering liquid embolic agents, sponges, vascular plugs, balloons, or coils[7-10]. Although embolization procedures may initially be effective, numerous studies have reported complications including ureter recanalization, coil migration, and PCN tube occlusion[11-13]. These procedures are also lengthy, which leads to significant anesthesia exposure for medically ill patients and predisposes both patients and the interventional radiology team to increased radiation exposure. Additionally, embolic agents are costly as are the instruments needed to deploy them.

Due to a high prevalence of urogenital fistulae, lack of standardized and cost-effective treatments, and limited efficacy of current treatment options, we propose a novel method of urinary tract fistula repair: Endoureteral ablation through light amplification by stimulated emission of radiation (laser) or radiofrequency ablation (RFA). Both laser ablation and RFA utilize the same basic principle: Converting energy to heat, leading to coagulative necrosis resulting in fibrosis and scar formation, which theoretically occludes the ureter[14]. RFA and laser ablation are currently used to treat benign and malignant tumors, varicose veins, nephroureteral calculi, and nerve pain. One noteworthy success involves cystoscopic-guided laser ablation in an animal model, effectively treating urinary incontinence in canines with ectopic ureters. The procedure encompasses identifying the ectopic ureter through cystoscopy, characterizing it under fluoroscopic guidance, and utilizing a diode laser wire for laser ablation. This procedure demonstrated safety and efficacy comparable to traditional surgical repair[15,16]. In the human model, various ablation techniques as treatment for urinary fistula have been recently published. In 2016, holmium laser ablation was successfully combined with partial vaginal excision for the treatment of a small vesicovaginal fistula; the patient remained fistula-free for at least 12 months following the procedure[17]. Additionally in 2024, microwave ablation was successfully utilized to treat a urinary fistula following a nephrectomy, which proved safe and successful, with no residual leakage[18].

Proper surgical planning and patient selection are of the utmost importance when discussing both patient safety and efficacy of treatment. Physicians performing the endoureteral ablation would undergo extensive training to operate laser equipment in an extremely precise and accurate manner; this would include training with the device manufacturers as well as simulation training to prepare for situations that may arise during the procedure. Patients selected for ablation would need to meet strict criteria and be evaluated during the preoperative planning phase to ensure to ensure the procedure is appropriate and safely carried out. Postoperatively, patients would be monitored closely through experienced nursing staff as well as frequent follow up visits with physicians to ensure successful treatment and monitor for complications. As with any medical procedure, complications are a possibility and must be discussed. We anticipate that endoureteral ablation may present similar complications to those observed in endovascular ablation, including ecchymosis, skin burns, pain, and infection[19]. Additionally, complications specific to the urogenital system, such as urinary tract infection or urinary stricture, may also occur. These complications are typically managed conservatively although severe adverse events may require further management, such as additional surgical intervention.

CONCLUSION

Ultimately, the early success in the animal and human models suggests that ablating the tissue surrounding the fistula orifice may cause fibrosis, thereby occluding the defect. This procedure has the potential to provide a more effective alternative to ureteral embolization with benefits of being less invasive, less costly, and improving likelihood of success. It also may provide a safer alternative for patients with small defects who would otherwise have to undergo invasive surgery to correct the fistulae as well as PCN tube and/or stent removal. Moreover, this technique may also be advantageous for patients with significant medical comorbidities who are not good surgical candidates. However, at this time, few human studies of endoureteral ablation exist. Therefore, we recommend further basic, translational, and clinical studies alike to explore endoureteral ablation for the treatment of urinary tract fistulae further and to identify whether our proposition is truly a viable option for patients. Until then, additional clinical studies are needed to translate early findings into meaningful results.