DOSE A URETERAL ACCESS SHEATH FACILITATE URETEROSCOPY?:

Safety And Efficacy of Ureteral Access Sheaths

The ureteral access sheath (UAS) was introduced as a means of passing a flexible ureteroscope. Although the device was initially lauded for its ability to facilitate ureteroscopic access, passage was difficult and risked ureteral injury, and the UAS fell out of favor until the development of a new generation of devices that was easier to insert. The UAS should be advanced under fluoroscopy over a stiff guidewire, and the surgeon should ensure copious hydration of all inner and outer surfaces. Use of the UAS is purported to improve irrigant flow and visibility. The UAS can induce transient ureteral ischemia and promote an acute inflammatory response, but it also prevents potentially harmful elevations in intrarenal pressure. Unequivocal data are not yet available to suggest that UAS use during ureteroscopy protects or harms the upper urinary tract. The UAS also has the potential to improve stone-free rates by allowing passive egress or active retrieval of fragments. A large prospective study is needed to unequivocally determine if UAS use is superior in terms of stone-free rates. Cost studies reported to favor UAS use, although a formal cost-effectiveness analysis has not been performed. Further study is needed before routine use of the UAS can be recommended.

Evaluation of the mechanisms of damage to flexible ureteroscopes and suggestions for ureteroscope preservation

AIM

To investigate the causes and costs of flexible ureteroscope damage, and to develop recommendations to limit damage.

METHODS

The authors analysed repair figures and possible causes of damage to 35 instruments sent for repair to a leading UK supplier over a 1-year period, and calculated cost figures for maintenance of the instruments as opposed to repair and replacement costs.

RESULTS

All damages were handling-induced and therefore did not fall under the manufacturer's warranty: 28 % were damaged by misfiring of the laser inside the instrument; 72 %, mainly crushing and stripping of the ureteroscope shaft tube, were likely to have occurred during out-of-surgery handling, washing and disinfection. Seventeen (4 %) instruments were not repaired and consequently taken out of service due to the extensive costs involved. Eighteen (51 %) ureteroscopes were repaired at an average cost of 10 833 USD.

CONCLUSION

Damages to flexible ureteroscopes bear considerable costs. Most damages occur during handling between surgical procedures. Thorough adherence to handling procedures, and courses for theater staff and surgeons on handling flexible instruments may help to reduce these damages and prove a cost-saving investment. The authors provide a list of recommended procedural measures that may help to prevent such damages.

Simultaneous combined use of flexible ureteroscopy and percutaneous nephrolithotomy to reduce the number of access tracts in the management of complex renal calculi

OBJECTIVE

To present early experience in managing complex renal calculi using a combined ureteroscopic and percutaneous approach, as complex and branched renal calculi often require multiple access tracts during percutaneous nephrolithotomy (PNL), and the combined use of flexible ureteroscopy and PNL has the potential to reduce the inherent morbidity of several tracts.

PATIENTS AND METHODS

The study included seven patients (mean age 54 years) with multiple, branched, large-volume renal calculi suitable for management with PNL. Preoperative data, including patient demographics, stone location and stone surface area, were recorded. After informed consent, the patients underwent combined PNL and ureteroscopy in one session. Intraoperative data, including the location of PNL puncture sites, operative duration and complications, were analysed. Stone-free rates were determined by follow-up imaging at 3 months.

RESULTS

All patients had either two or more stones in separate locations in the collecting system, or staghorn stones involving multiple calyces. The mean stone burden was 666 mm(2). All patients had only one percutaneous access tract. The mean operative duration was 142 min and the mean blood loss 79 mL. Two patients had small residual stones (< 3 mm), that required ureteroscopic intervention as they failed to pass spontaneously by 3 months after the initial combined procedure. The convalescence was similar to that in our current PNL practice; imaging showed that five of the patients were stone-free.

CONCLUSIONS

Combined PNL and ureteroscopic management can effectively reduce the number of percutaneous access tracts which would otherwise be required for managing complex and branched renal calculi, as stones in an unfavourable location relative to the access tract can be relocated and fragmented within easy reach of the single nephrostomy tract. This manoeuvre reduces potential patient morbidity and blood loss but with no significant effect on stone-free rates and operative durations.

Ureteral access sheath provides protection against elevated renal pressures during routine flexible ureteroscopic stone manipulation

BACKGROUND AND PURPOSE

New-generation flexible ureteroscopes allow the management of proximal ureteral and intrarenal pathology with high success rates, including complete removal of ureteral and renal calculi. One problem is that the irrigation pressures generated within the collecting system can be significantly elevated, as evidenced by pyelovenous and pyelolymphatic backflow seen during retrograde pyelography. We sought to determine if the ureteral access sheath (UAS) can offer protection from high intrarenal pressures attained during routine ureteroscopic stone surgery.

PATIENTS AND METHODS

Five patients (average age 72.6 years) evaluated in the emergency department for obstructing calculi underwent percutaneous nephrostomy (PCN) tube placement to decompress their collecting systems. The indications for PCN tube placement were obstructive renal failure (N=1), urosepsis (N=2), and obstruction with uncontrolled pain and elevated white blood cell counts (N=2). Flexible ureteroscopy was subsequently performed with and without the aid of the UAS while pressures were measured via the nephrostomy tube connected to a pressure transducer. Pressures were recorded at baseline and in the distal, mid, and proximal ureter and renal pelvis, first without the UAS, and then with the UAS in place.

RESULTS

The average baseline pressure within the collecting system was 13.6 mm Hg. The mean intrarenal pressure with the ureteroscope in the distal ureter without the UAS was 60 mm Hg and with the UAS was 15 mm Hg. With the ureteroscope in the midureter, the pressures were 65.6 and 17.5 mm Hg, respectively; with the ureteroscope in the proximal ureter 79.2 and 24 mm Hg, and with the ureteroscope in the renal pelvis 94.4 and 40.6 mm Hg, respectively. All differences at each location were statistically significant (P<0.008). Compared with baseline, all pressures measured without the UAS were significantly greater, but only pressures recorded in the proximal ureter and renal pelvis after UAS insertion were significantly higher (P<0.03).

CONCLUSIONS

The irrigation pressures transmitted to the renal pelvis and subsequently to the parenchyma are significantly greater during routine URS without the use of the UAS. The access sheath is potentially protective against pyelovenous and pyelolymphatic backflow, with clinical implications for the ureteroscopic management of upper-tract transitional cell carcinoma, struvite stones, or calculi associated with urinary tract infection.

Endoscopic management of symptomatic caliceal diverticula: a retrospective comparison of percutaneous nephrolithotripsy and ureteroscopy

BACKGROUND AND PURPOSE

A myriad of minimally invasive options exist for managing symptomatic caliceal diverticula, including shockwave lithotripsy, percutaneous surgery, retrograde ureteroscopy, and laparoscopy. Yet no direct comparisons have been made in the literature of the relative treatment efficacy of ureteroscopy (URS) and percutaneous nephrolithotripsy (PNL). A retrospective review of our patients was performed to determine the most appropriate endoscopic management option for patients with symptomatic caliceal diverticula.

PATIENTS AND METHODS

Between November of 1994 and April 2001, 39 patients presented with symptomatic caliceal diverticula, 37 of which contained calculi. Twenty-two patients (56%) underwent PNL, and 17 patients (44%) were managed by URS. Of the PNL group, 82% required the creation of a neoinfundibulotomy. The stone burden in the PNL group averaged 11.4 x 12.0 mm and that in the URS group 12.7 x 13.0 mm (p > 0.05). Pain, recurrent urinary tract infections, and nausea and vomiting were the presenting complaints in both subgroups of patients, with pain being by far the most common symptom. The average hospital stay was 2.8 days for the PNL group. All the URS procedures were performed on a same-day-surgery basis. Results, including stone-free, symptom-free, and complication rates, were compared for the two groups.

RESULTS

Thirty-five percent of the URS group were symptom free at 6 weeks' follow-up, with an additional 29% reporting an improvement in pain, whereas 86% of the PNL group was completely symptom free at 6 weeks' follow-up. Only 19% of the URS group were stone free on follow-up intravenous urography v 78% of those undergoing PNL (three patients failed to return for follow-up imaging). It was not possible to identify the ostium of the stenotic infundibulum in 4 patients (24%) undergoing URS, and 7 patients (41%) eventually went on to PNL with ultimate success. The PNL was statistically better than URS in producing stone-free results for diverticula located in the upper pole and for stones <11 mm (p < 0.05). No complications occurred in the URS group; however, complications were identified in four patients after PNL. One patient developed clot urinary retention necessitating Foley catheterization and manual bladder irrigation; one patient experienced significant bleeding necessitating early cessation of the procedure. Two patients sustained intrathoracic complications, one a pneumothorax and the other a pneumohemothorax after supra-11(th) rib access. Both were managed successfully with tube thoracostomy.

CONCLUSIONS

Our review clearly suggests an advantage of percutaneous management over ureteroscopy for complex posterior symptomatic caliceal diverticula, although with a slightly increased risk of complications. Therefore, PNL should be considered the primary modality for managing these difficult processes. In cases where the stenotic infundibulum cannot be traversed with a guidewire, creation of a neoinfundibulotomy permitted secure access to the collecting system while providing effective results.

Laser Doppler flowmetric determination of ureteral blood flow after ureteral access sheath placement

BACKGROUND AND PURPOSE

The ureteral access sheath has positively impacted ureteroscopy by decreasing operative times and increasing success rates. However, as previous studies have suggested that large-caliber endoscopes may cause ureteral ischemia, concern has been raised about the impact of access sheath insertion on ureteral blood flow. We sought to determine whether the access sheath compromises ureteral blood supply and, if so, causes ischemic damage to the ureter during ureteroscopic procedures.

MATERIALS AND METHODS

Using a swine animal model, ureteral blood flow was measured with a laser Doppler flowmeter. Eleven ureteral units were randomized into four study groups: those dilated with 10F-12F, 12F-14F, and 14F-16F access sheaths (N = 3 per group) and an undilated control group (N = 2). Blood flow measurements were obtained from the proximal ureter via laser Doppler flowmetry for 70 minutes at 5-minute intervals. Hemodynamic variability was controlled for through intraoperative heart rate and oxygen saturation monitoring, as well as a second Doppler probe that was placed on the animal's skin, from which readings were also taken every 5 minutes. Results were correlated with histopathologic findings.

RESULTS

The control group demonstrated little ureteral blood flow variability over the course of 70 minutes. The study groups that were dilated with sheaths, however, all showed a decrease in ureteral blood flow after access sheath insertion, with the flow in animals dilated with 12F-14F and 14F-16F sheaths dropping below 50% of baseline. This initial drop in blood flow was followed by a gradual increase from nadir toward baseline values over the course of the study. On average, the 14F-16F group reached nadir more quickly and took longer to restore its ureteral blood flow. All animals remained hemodynamically stable throughout the study, showing only minimal variability in heart rate, oxygen saturation, and skin blood flow over the 70-minute experiment. Histologically, there was no evidence of ischemic damage in any of the study groups at 72 hours.

CONCLUSIONS

In this animal model, the access sheath does cause a transient decrease in ureteral blood flow. Nonetheless, compensatory mechanisms of the ureteral wall restore blood flow to near-baseline rates and preserve urothelial integrity, suggesting that use of the ureteral access sheath remains a safe adjunct to flexible ureteroscopy. Because the chronic effects of the access sheath have yet to be elucidated, care must be taken in selecting an appropriate-size sheath for each individual case. Preventive measures may be available to help avoid sheath-related ureteral injury in those patients identified as high risk.

Ureteral access for upper urinary tract disease: the access sheath

Ureteral access with the flexible ureteroscope remains a challenge for the urologist. The routine use of a newly developed, site-specific ureteral access sheath facilitates entry into the ureter for fragmentation and basket extraction of ureteral and renal calculi. The step-by-step technique of ureteral access with the Access Sheath is described.