Hideyuki Terao

Ureteral stent encrustation, incrustation, and coloring: morbidity related to indwelling times.

BACKGROUND AND PURPOSE Ureteral stents are a fundamental part of many urologic procedures. Serious complications, including migration, fragmentation, and stone formation, still occur, especially when stents have been forgotten for a long time. No widespread consensus for the type or indwelling time to avoid ureteral stent complications has been reached, however. We investigated the correlation between the indwelling time and encrustation, incrustation, coloration, and resistance to removal. PATIENTS AND METHODS A total of 330 ureteral stents in 181 patients were examined. RESULTS Overall, 155 (47.0%) stents were encrusted, and the encrustation rate was 26.8% at less than 6 weeks, 56.9% at 6 to 12 weeks, and 75.9% at more than 12 weeks. A total of 46 (13.9%) stents resisted removal, and 3 of these could not be removed by cystoscopy. The median indwelling time was 72 (14-124) days for stents that resisted removal and 31 (30-60) days for irremovable stents. The frequency of encrustation with coloration was higher than that without coloration in the period of less than 6 weeks and the period between 6 to 12 weeks of indwelling time. CONCLUSIONS In our study, although ureteral stent encrustation was related to the indwelling time, heavily encrusted ureteral stents necessitating additional procedures for removal occurred within an indwelling time of 3 months. The exact interval for removal of an indwelling ureteral stent to avoid additional procedures for removal is therefore difficult to determine.

Ureteroscopy assisted retrograde nephrostomy: a new technique for percutaneous nephrolithotomy (PCNL).

Study Type – Therapy (case series)

Predictive Value of Attenuation Coefficients Measured as Hounsfield Units on Noncontrast Computed Tomography During Flexible Ureteroscopy with Holmium Laser Lithotripsy: A Single-Center Experience

PURPOSE To assess the utility of attenuation coefficients as predictors of surgical outcome after a single flexible ureteroscopy (URS) with holmium laser lithotripsy. Many reports indicate that the efficacy of extracorporeal shockwave lithotripsy (SWL) can be predicted by the targets radiofrequency attenuation, measured as Hounsfield units (HUs) on noncontrast CT (NCCT). Studies of flexible URS, however, have not assessed the predictive value of attenuation coefficients on NCCT. PATIENTS AND METHODS Patients with renal stones who were treated by flexible URS with holmium laser lithotripsy between December 2009 and October 2011 at a single institute were retrospectively evaluated. Stone-free (SF) status was determined by kidneys-ureters-bladder (KUB) radiography at postoperative month 3. Correlations of possible predictors with SF status were analyzed using a logistic regression model. The comparison between groups with low and high HUs was examined using the Mann-Whitney U test. RESULTS There were 219 eligible procedures. According to the logistic regression model, the maximum attenuation coefficient (P=0.105) and average attenuation coefficient (P=0.175) did not significantly, independently predict SF status. Fragmentation efficiency was significantly different between cases with low and high attenuation coefficients (P=0.001). In groups with less than 20.0-mm diameter stones, overall operative time (P<0.001 and P=0.001) and the time from starting fragmentation (P<0.001 and P=0.002) were significantly high in both attenuation groups. In groups with stones greater than 20.0 mm diameter, the two definitions of operative time revealed no differences between the low and high attenuation groups. The retrospective study design was the major limitation of this study. CONCLUSIONS We found that both the maximum and average attenuation coefficients on NCCT are significantly related to the fragmentation efficiency. In addition, this study showed that, in patient groups with stone a burden <20.0 mm in diameter, both the maximum and average attenuation coefficients were significantly predictive of operative time.

Contrast-enhanced ultrasonography of the prostate: various imaging findings that indicate prostate cancer

Study Type – Diagnostic (non‐consecutive case series) 
Level of Evidence 3b

The Most Reliable Preoperative Assessment of Renal Stone Burden as a Predictor of Stone-free Status After Flexible Ureteroscopy With Holmium Laser Lithotripsy: A Single-center Experience

OBJECTIVE To examine which parameters should be measured to preoperatively determine the stone burden as predictors of stone-free (SF) status after a single flexible ureteroscopy (URS). Although several stone parameters reportedly influence the outcome of treatment for urinary stones, the most reliable indicators of stone burden remain unclear. METHODS Patients with renal stones treated by flexible URS with holmium laser lithotripsy between October 2009 and December 2011 at a single institute were retrospectively evaluated. The SF status was determined by kidney-ureter-bladder (KUB) films at postoperative day 1. Correlations of possible predictors with the SF status were analyzed using a logistic regression model. RESULTS According to the univariate analysis, the following variables were significantly associated with failed treatment: number of stones (P = .001), cumulative stone diameter (CSD) (P < .001), stone surface area (SA) (P < .001), stone volume (P < .001), and presence of lower pole calculi (P = .008). According to the multivariate analysis, the stone volume (P < .001) and the CSD (P = .015) were found to be independent predictors of SF status. The SA (P = .598) had no significant independent influence on the SF status. CONCLUSION Among the several parameters regarding the renal stone burden, the stone volume determined by noncontrast computed tomography and the CSD of the KUB were significantly and independently inversely related to the success rate of URS. Among the 3 parameters of stone burden, the SA was found to have a lower clinical utility and priority as a predictor of a SF status after URS.

Preoperative stenting for ureteroscopic lithotripsy for a large renal stone

A large renal stone can be treated ureteroscopically, but the treatment often requires more than one procedure. The use of stenting before ureteroscopy was recently reported. The present study investigated the effectiveness of preoperative stenting before ureteroscopic lithotripsy for large (>15 mm) renal stones. A ureteral stent was intentionally inserted in 25 patients undergoing ureteroscopic surgery. A group of 36 non‐prestented patients was used as control. Median stone diameter was 21 mm in both groups. Pre‐ureteroscopy stenting significantly improved the stone‐free rate, defined as stones <2 mm and <4 mm (P < 0.05), whereas it did not significantly improve the stone‐free rate defined as 0 mm (P = 0.12). The uretereoscopy success rate was 72.0% in the stented and 55.6% in the control group (P = 0.09). A 14/16‐Fr ureteral access sheath was successfully inserted in 94.7% of the stented patients, and 74.2% of the non‐stented patients (P < 0.05). Our findings showed that preoperative stenting is effective for dilation of the ureter, and also to facilitate the insertion of a ureteral access sheath in patients undergoing ureteroscopic lithotripsy for large renal stones.

Development and internal validation of a nomogram for predicting stone-free status after flexible ureteroscopy for renal stones.

To develop and internally validate a preoperative nomogram for predicting stone‐free status (SF) after flexible ureteroscopy (fURS) for renal stones, as there is a need to predict the outcome of fURS for the treatment of renal stone disease.

Choosing an Appropriate Length of Loop Type Ureteral Stent Using Direct Ureteral Length Measurement

Purpose: The ureteral stent is now a fundamental part of many urological procedures. To decrease ureteral stent-related symptoms, loop type ureteral stent was developed. However the most important factor to decrease urinary symptoms is choosing the optimal length of a ureteral stent. We investigated the relationship between the actual ureteral length and the loop type ureteral stent position. Materials and Methods: A total of 226 loop type polyurethane ureteral stents (156 patients) were inserted with four options for stent length (20, 22, 24 and 26 cm). The ureteral length was measured using a ruled 5-Fr ureteral catheter. The appropriateness of stent position was defined into three groups based on kidney-ureter-bladder films. Results: Nine stents (3.9%) migrated, 171 stents (75.7%) were in the appropriate position and 46 stents (19.5%) were overlong. The rate of migration rate and overlong stents closely correlated with the ureteral length when the proximal end of the stent was in the renal pelvis. Conclusions: It is appropriate to choose a loop type ureteral stent that is the same or 1 cm less than the length of the ureter when the proximal end of the stent will be in the renal pelvis.

Ureteral Stent Retrieval Using the Crochet Hook Technique in Females

Introduction We developed a method for ureteral stent removal in female patients that requires no cystoscopy or fluoroscopic guidance using a crochet hook. In addition, we also investigated the success rate, complications and pain associated with this procedure. Methods A total of 40 female patients (56 stents) underwent the removal of ureteral stents. All procedures were carried out with the patients either under anesthesia, conscious sedation, or analgesic suppositories as deemed appropriate for each procedure including Shock Wave Lithotripsy (SWL), Ureteroscopy (URS), Percutaneous Nephrolithotomy (PCNL), and ureteral stent removal. At the time of these procedures, fluoroscopy and/or cystoscopy were prepared, but they were not used unless we failed to successfully remove the ureteral stent using the crochet hook. In addition, matched controls (comprising 50 stents) which were removed by standard ureteral stent removal using cystoscopy were used for comparison purposes. Results A total of 47 of the 56 stents (83.9%) were successfully removed. In addition, 47 of 52 (90.4%) were successfully removed except for two migrated stents and two heavily encrusted stents which could not be removed using cystoscopy. Ureteral stent removal using the crochet hook technique was unsuccessful in nine patients, including two encrustations and two migrations. Concerning pain, ureteral stent removal using the crochet hook technique showed a lower visual analogue pain scale (VAPS) score than for the standard technique using cystoscopy. Conclusions Ureteral stent removal using a crochet hook is considered to be easy, safe, and cost effective. This technique is also easy to learn and is therefore considered to be suitable for use on an outpatient basis.

Effectiveness of Ureteroscopy-Assisted Retrograde Nephrostomy (UARN) for Percutaneous Nephrolithotomy (PCNL)

Objective To determine the impact of ureteroscopy-assisted retrograde nephrostomy (UARN) during percutaneous nephrolithotomy (PCNL). Materials and Methods From April 2009 to September 2011, a total of 50 patients underwent PCNL for large renal stones (stone burden >2 cm). We performed UARN in the Galdakao-modified Valdivia position for 27 patients (UARN PCNL) and ultrasonography-assisted percutaneous nephrostomy in the prone position for 23 patients (prone PCNL). Results UARN PCNL significantly improved the stone-free rate (81.5% vs 52.2%) and the rate of residual stones (<4 mm, 92.6% vs 65.2%, P<0.05). The median length of the operation was significantly shorter for UARN PCNL, at 160 min, compared to 299 min for prone PCNL (P<0.001). There was one intraoperative complication in prone PCNL, namely a hemorrhage that resulted in stopping the initial treatment, but it was cured conservatively. The postoperative complications included a high grade fever that persisted for three days in two UARN PCNL patients (7.4%) and six prone PCNL patients (26.1%). The Clavien grading scores showed significantly lower postoperative complications for UARN PCNL compared to prone PCNL. Conclusion UARN is associated with a higher stone-free rate, shorter operation time, and fewer complications during PCNL than prone PCNL.