V03-09: Complicated removal of an encrusted Allium™ ureteral stent
Allium stents are indicated for long-term stenting of lower ureteral stenoses and are fully covered by a polymeric coating designed to prevent tissue in-growth into the lumen as well as reduce encrustation, stone formation and calcification. According to the manufacturer’s instructions for use, Allium stents are easy to remove. We report about a complicated removal of an encrusted Allium ureteral stent.
A 66 years old male had an Allium stenting of his right distal ureter 9 months ago at our institution. He suffered from a distal ureteral stenosis causing a urine outflow obstruction and was known for recurring stone disease. We agreed for a diagnostic ureteroscopy (Flex Xc, Karl Storz, Germany) and stent removal trial with the patient.
A retrograde ureteropyelography revealed full patency of the Allium stent. Diagnostic ureteroscopy revealed calcifications along the entire inner lumen of the stent. Identification of the distal nitinol loop of the Allium stent allowed us to perform the first extraction trial. We chose a 3.0 Fr Boston scientific Tricep to securely anchor the distal nitinol loop. Despite several trials, we were not able to extract the Allium stent hereby. We then inserted a 3.0 Fr Boston scientific Piranha forceps over a semi-rigid ureteroscope. The extraction of the stent was not possible by these means either. Finally, a foreign-body grasper inserted over the semi-rigid ureteroscope made the extraction of the Allium stent possible. High force levels were necessary to extract the stent. The coating of the Allium stent got ripped off the nitinol wires and a spontaneous rupture of the stent occurred during stent extraction. Unraveling of the stent did not occur. A control ureteropyelography did not reveal any contrast media extravasation. A control ureteroscopy showed extended mucosa oedema with several mucosal lesions Grad I according to the Traxer classification. Noteworthy, a few additional calcifications were found between the former external surface of the Allium stent and the ureteral mucosa. In light of the complicated stent removal, we decided to replace the Allium stent by two double J Tumorstents (7F / 30 mm, Bard). The insertion was performed in a parallel manner.
This video teaches us that Allium ureteral stent removal is not always as easy as stated by the manufacturer. In this particular case, the unraveling of the stent did not occur and may have been responsible for the high resistance to extraction. Potential complications such as stent calcification and ureteral mucosa damage have to be considered whenever an Allium stent has been inserted.