Ureteral Stents: Lifeline of Endourology
The use of ureteric stents is increasing and the list of indications for their use has expanded from temporary or permanent relief of ureteric obstruction to include temporary urinary diversion following surgical procedures on the urinary tract and stents are being used at a ‘drop of the hat’. Unfortunately, there remain many problems associated with the use of stents.
The increasing tendency to insert a stent at an earlier opportunity than before, on the basis that it will reduce morbidity of, for example, ureteric obstruction, is occurring at the cost of considerable discomfort to patients. The sequelae of stent insertion are under-reported and the incidence of stent removal or replacement is high.
Perhaps more worrying is the suggestion from clinical studies that stenting does not reliably relieve obstruction, commonly the very reason for stent insertion in the first place. This finding may be influenced by type of stent used, the material from which the stent is made, and the reason for the ureteric obstruction in the first place.
What properties would an ideal stent have to possess? The pathophysiological properties relate to the effect of the stent on ureteric mucosa and ureteric function and the effect of urine on the stent. These effects reflect the biocompatibility of the stent. Many physical properties of the stent material will affect both performance and comfort of the patient; these include tensile strength, compliance, flexibility and elasticity, and surface characteristics such as wettability and smoothness. The ideal stent material should possess the ability to resist fouling with formation of Biofilm and Encrustation.
For the patient, the stent should be inert and its presence should not be noticeable. The surgeon requires a stent that has a smooth profile for easy insertion and removal, a wettable surface on demand (for ease of insertion past obstructing stones, for example), good flexibility, and good ease of passage over a guide wire. For the purchaser, even the highest-quality product should still be affordable.
Of late several new stent materials have evolved having most of the qualities needed for a stent. But still this is an evolving area with many limitations to overcome. Despite the advances in Stent Design and Material, the morbidity associated with Ureteric Stents should make the urologists ask ‘Is a Stent really necessary’. It is true when it is said that ‘an Ideal Stent is not yet available’ and may be so for ‘years to come’.
There is a podcast by Dirk Lange (Episode 28in the latest issue) of Endourology Sound bites on ‘New Insights into Ureteral Stents’ which is worth listening and Understanding. (It has the previous sound bites as well for those interested)
On 8th August 2020, there was a Webinar Moderated by Vineet Gauhar on behalf of ITRUE on ‘Stents: Lifeline of Endourology’. One of the participants among the Galaxy of speakers was Ben Chew and he spoke on ‘Stents and Biomaterials’ which is worth listening to apart from other talks. I am providing the Link from which you can listen to this excellent Webinar if you did not have an opportunity earlier.
Many speakers who spoke in the webinar have extensively quoted from the articles Provided (links).
Finally I am providing a book edited Daniel Yachia, 2nd Ed 2004 on ‘Stenting of the Urinary System’. (PDF attached).
(If the Link does not open, for those interested I can provide the book)
It is with great pleasure I am providing these materials for knowledge need be disseminated and not kept to oneself.
With warm Regards,