In 2025, stone disease prevalence and incidence are increasing worldwide, and a retrograde approach is the most common endourologic procedure.

Smaller scopes, suction scopes, suction ureteral access sheaths, and lasers with more power allow treatment of high-burden stones in a retrograde fashion, but unfortunately, after these retrograde procedures, an increasing number of ureteral strictures have occurred. These strictures lead to long-term patient morbidity, increased health care costs, and reduced quality of life.¹

The most dangerous scenario for ureteral strictures is impacted ureteral stones. The degree of hydronephrosis, ureteral wall thickness, and number of Hounsfield units of the ureteral wall below the stone have been described as predictors of stone impaction. Ureteral stricture is a significant complication following laser treatment for impacted stones and occurs in up to 25% of cases. If we add damages caused by the stone and thermal injuries, the combination of impacted stone, inadequate laser setting, low irrigation, and prolonged laser time can be “the sum of all fears.”²

As described by the Ralph Clayman group in 2016, mechanical damage occurring during a ureteroscopy can be managed with double-J stent placement and time, but thermal injuries are different. Boiled or burned ureters cannot be resolved with a double-J stent and time.³

Thermal injuries are caused by the rising temperature around the tip of the laser fiber. When temperature exceeds 43 °C, cell damage, protein coagulation, and tissue injury occur, subsequentially progressing to a ureteral stricture. Above 43 °C, the time required to cause cellular damage decreases by half. This means that, after a few seconds of using inadequate settings and/or low fluid irrigation, the probability of ureteral stricture development strongly increases.

Thermal injuries are intricately related to laser power, laser time, and fluid irrigation. High-­frequency and/or high-energy settings will increase total power; therefore, the safety limit has been described as total power less than 12 to 15 watts and the use of low frequencies.

Other causes of ureteral strictures are failed pyeloplasty procedures. Since 1993, laparoscopic pyeloplasty became the treatment of choice for ureteropelvic junction obstructions. Ureteral stricture following laparoscopic pyeloplasty has been reported in between 2.5% and 10% of procedures, but compared with ureteral stricture after ureteroscopy, these numbers seem stable.

For the past 60 years, incision and dilation have been the 2 major techniques used to treat ureteral strictures.

Endoureterotomy with a standard urethrotome was described by John Edward Wickham from St Bartholomew’s Hospital in London in 1983 using a percutaneous approach.⁴ After Wickham’s reported cold incision, electrocautery incision or laser incision was described with similar results, with a 60% to 95% success rate and a median follow-up of 10 months. Laser incision has the advantage of being used with semirigid to flexible scopes and, comparing different lasers, a thulium fiber laser produces a precise cut, has the shortest tissue penetration, and can be used with smaller fibers.

The concept of incision and self-healing was described by David M. Davis from Jefferson Medical College in Philadelphia in 1948.⁵ Among the questions Dr Davis asks in his paper, “How does the ureter and particularly its muscularis heal around the tube?” is the key to understanding the target of paclitaxel-coated balloons. Paclitaxel is an inhibitor of ureteral smooth muscle cell proliferation and collagen production, which regulates the healing process.

Balloon dilation was described by Marc Banner from Pennsylvania University in 1983 and had a success rate of 47%.⁶ In 2019, Javier Zeballos from Uruguay showed the first use of a paclitaxel and dextran–coated balloon to treat a ureteral stricture.⁷ Interestingly, balloon dilation with coated balloons seems to add some benefits, answering Davis’s question related to smooth muscle cell proliferation.

The use of paclitaxel as an inhibitor of ureteral smooth muscle cell proliferation and collagen production was described in animal models more than 20 years ago. Also, prevention in hyperplastic proliferation of ureteral tissue was found in vitro. Paclitaxel-coated balloons received Food and Drug Administration approval for urethral strictures after the clinical trial published by Ramon Virasoro from Eastern Virginia Medical School in 2020.⁸

In 2022, Panagiotis Kallidonis from the University of Patras published the results of 25 patients with ureteral strictures treated with a paclitaxel-coated balloon, with a success rate of 88% after 1 year of follow-up.⁹

A paclitaxel and dextran–coated balloon received CE (conformité européenne) marking for the treat­ment of fibrotic strictures. Its use in the ureter is supported by clinical data but may require case-by-case clinical justification. The use of dextran polymer as the ­controller of drug delivery has been studied in peripheral arteries and showed a better release pattern compared with paclitaxel-only–coated ­balloons. In 2024, at the 41st World Congress of Endourology, our group from Uruguay and Argentina showed the results of 21 patients with ureteral strictures following ureteroscopic or laparoscopic procedures using a paclitaxel and dextran (2/1 ratio: 2.2 μg paclitaxel and 0.7 μg dextran)–coated balloon with a success rate of 90% and a median follow-up of 21 months (Figure).¹⁰

In summary, ureteral strictures are a real problem in our daily ­endourologic practice, and their incidence seems to be increasing. As with any other iatrogenic event, ­prevention is the key.

Quick treatment for impacted stones and proper laser, fluid, and time settings are unequivocal parts of the strategies to prevent ureteral strictures. The use of paclitaxel-­coated balloons to prevent strictures after ureteroscopy in impacted stones needs to be proven but appears to be an interesting idea.

There are proven benefits of using paclitaxel and dextran–coated balloons to perform dilation of a ureteral stricture. They act in the pathogenesis of the stricture by inducing fibrosis and recurrence.

In summary, paclitaxel-coated balloons provide added value to an old practice.

Conflicts of Interest: Dr Contreras is a consultant for AR Baltic Medical. Dr Zeballos is a speaker for AR Baltic Medical.