The Impact of One Week of Pre-Stenting on Porcine Ureteral Luminal Circumference.

Objectives: Larger ureteral access sheaths (UASs) have the potential to improve ureteroscopic stone removal outcomes but are often avoided by surgeons because of concerns of ureteral injury. Using our novel UAS force sensor and previously defined force thresholds for ureteral injury, we sought to evaluate the impact of 1 week of stenting on the maximum safe dilation of ureteral luminal circumference. Methods: Twelve juvenile female Yorkshire pigs (24 ureters) were evaluated. The inner (i.e., luminal) circumference of each ureter was determined using Cook urethral dilators ranging from 8F to 24F in 2F increments, 37 cm in length. Each dilator was sequentially passed while applying the UAS force sensor to measure insertion force before and after 1 week of stent placement. Each ureter was randomized to receive either a 4.7F or 7.0F stent (20 cm). Maximum ureteral luminal circumference was defined as effective passage of the dilator to the ureteropelvic junction with ≤6 newtons (N) of force (the force threshold previously defined by porcine and clinical studies to avoid ureteral damage). After passage of the largest dilator at 6 N, flexible ureteroscopy was performed and a post-ureteroscopic lesion scale (PULS) was recorded. Results: After 1 week of stent placement, the median ureteral luminal circumference increased to 15F representing a mean increase of 3.8F ± 2.8F (p < 0.001). Twenty-one (88%) of the pre-stented ureters had an increase in luminal circumference, with 12 ureters (50%) dilated to ≥16F (p = 0.032), 6 ureters (25%) dilated to ≥18F, and in 2 cases a maximum size of 24F was recorded. The PULS grade was ≤2 in all cases, indicating no high-grade ureteral injuries. Laterality and stent size did not impact ureteral luminal circumference after pre-stenting (p = 0.232 and p = 0.337, respectively). Conclusions: One week of ureteral stenting resulted in nearly a 4F increase in the luminal circumference of porcine ureters.

Comparison of silicone versus polyurethane ureteral stents: a prospective controlled study.

BACKGROUND: Approximately 80% of patients with indwelling ureteral stents experience stent related symptoms (SRS). We believe SRS can be reduced through altering the composition of ureteral stents to a less firm material. Therefore, we aim to compare modern silicone and polyurethane ureteral stents in terms of SRS intensity and safety. METHODS: From June 2018 to October 2018, patients from two distinct clinical centers were prospectively enrolled in the study and stratified (non-randomly) into either control group A, patients who received polyurethane stents (Rüsch, Teleflex), or experimental group B, patients who received silicone stents (Cook Medical). Each participant completed a survey 1 h after stent insertion, in the middle of the stent dwelling period, and before stent removal or ureteroscopy noting body pain and overactive bladder via the visual analog scale pain (VASP) and overactive bladder (OAB) awareness tool, respectively. Additionally, successfulness of stent placement, hematuria, number of unplanned visits, and stent encrustation rates were assessed within each group. RESULTS: A total of 50 patients participated in the study, control group A consisted of 20 patients and experimental group B consisted of 30 patients. Participants in group B, silicone ureteral stents, demonstrated significantly lower mean values of VASP 2 weeks prior to stent removal and promptly before stent removal (p = 0.023 and p = 0.014, respectively). No other comparisons between the two groups were statistically significant. CONCLUSIONS: Compared to polyurethane ureteral stents, silicone ureteral stents are associated with lower body pain intensity assessed by VASP 2 weeks before stent removal and at the time of stent removal. TRIAL REGISTRATION: Current Controlled Trials NCT04000178. Retrospectively registered on June 26, 2019.