Two Weeks Too Long: Optimal Duration for Ureteral Prestenting and Its Physiologic Effects on the Ureter in a Yorkshire-Landrace Pig Model

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

OBJECTIVES

Larger ureteral access sheaths (UAS) have the potential to improve ureteroscopic stone removal outcomes, but are often avoided by surgeons due to 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 one 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 8-24Fr in 2Fr increments, 37cm in length. Each dilator was sequentially passed while applying the UAS force sensor to measure insertion force before and after one week of stent placement. Each ureter was randomized to receive either a 4.7Fr or 7.0Fr stent (20cm). Maximum ureteral luminal circumference was defined as successful 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). Following passage of the largest dilator at 6N, flexible ureteroscopy was performed and a post-ureteroscopic lesion score (PULS) was recorded.

RESULTS

After one week of stent placement, the median ureteral luminal circumference increased to 15Fr representing a mean increase of 3.8Fr + 2.8 (p<0.001). Twenty-one (88%) of the pre-stented ureters had an increase in luminal circumference, with 12 ureters (50%) dilated to >16Fr (p=0.032), six ureters (25%) dilated to >18Fr, and in two cases a maximum size of 24Fr 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 4Fr increase in the luminal circumference of porcine ureters.

In Vivo Evaluation of a Novel Pigtail Suture Stent

OBJECTIVE

To compare pressure, dilation, and histology in a porcine model after stenting with a pigtail suture stent (PSS)-where the ureteral and bladder component consists of a suture and a double J (DJ) stent.

METHODS

Twelve pigs were studied with a PSS (4.8F/MiniJFil®) and DJ stent (4.8F/RocaJJ Soft) inserted in both sides, except in one where the DJ was not placed to serve as control. Intrapelvic pressure (IPP) and ureteral pressures were recorded. Five pigs were stented for 7 days, and the next 7 for 13-15 days, where a retrograde study was performed after stent removal. Ureteral histology in 4 and 3 pigs stented for 7- and 13-15 days, respectively, were assessed in a blinded manner.

RESULTS

In total, 11 renal units were stented with PSS and DJ, respectively. There was a rise in IPP and ureteral pressure after stenting. There were no significant differences in post-stenting pressures between DJ and PSS systems. Ureteral dilation occurred in 100% of DJ and 83% of PSS units. PSS suture migration occurred in 3 of 11. Gross edema at the ureteral orifice was greater with the DJ compared to the PSS (82% vs 18%; p = .003). Histology demonstrated greater inflammation at the ureteral orifice in the DJ group (2.3 vs 1; p = .016) when stented for 13-15 days.

CONCLUSION

There was no difference in IPP after stenting with a PSS compared to a DJ stent. When stented for 13-15 days, the PSS resulted in ureteral dilation, but with less edema and inflammation at the ureteral orifice.

Clinical Effectiveness of Single Pigtail Suture Stent on Patient Comfort: A Double-Blind Prospective Randomized Trial

Background: A double-pigtail ureteral stent (DPUS) can cause untoward symptoms, such as urgency, frequency, urinary incontinence, hematuria, and body pain that are bothersome to patient's quality of life (QoL). By reducing the quantity of material in the bladder, it could be reasonable to decrease stent-related symptoms (SRSs). We aimed to evaluate the tolerability of single pigtail suture stent (SPSS) with a validated questionnaire after uncomplicated retrograde semirigid ureteroscopic lithotripsy (URSL). Materials and Methods: A total of 130 patients who underwent ureteral stent placement after URSL for unilateral symptomatic ureteral stones with <15 mm diameter were randomized prospectively into two groups. Polyurethane ureteral stent (6 Fr, 24 or 26 cm) was placed in all patients, which was removed postoperatively with a mean of 14 days. There were 65 patients in both groups. All subjects completed the ureteral stent symptoms questionnaire (USSQ), which explores the SRSs. The questionnaires were conducted on the day of stent removal (at week 2) with the stent in situ and 4 weeks after removal (at week 6, poststent). The severity of SRSs and QoL were compared between the two groups. Results: SPSS was associated with perfect effect on all domains of USSQ, except from sexual and general health index scores. Pain index scores, visual analog scores (VAS), and analgesic requirements in SPSS group were found significantly low compared with those in the DPUS group. The QoL scores were significantly better in patients indwelling SPSS. Conclusion: SPSS is a potentially beneficial option to minimize ureteral SRSs after uncomplicated URSL.