Ureteral stents and flexible ureterorenoscopy

The Approach to the Ureter by Ureteroscopy

Ureteroscopy has an important role in the practice of the modern urologist. The procedure is usually performed under locoregional anaesthesia even if general anaesthesia is still considered the standard.

Placement of a guide wire (safety guide wire) represents the starting point to perform safely a ureteroscopy, just in case of complications during the endoscopic manoeuvres. There is no consensus on dilation of the ureteral orifice and on ureteral stenting at the end of the procedure.

Dilation of the ureteral lumen directly under vision as well as the use of ureteral sheath can be considered in particular cases.

Ureteroscopy is largely performed in many urologic centers at the present, but it requires ability and experience.

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.

Routine ureteral stenting is not necessary after ureteroscopy and ureteropyeloscopy: a randomized trial

BACKGROUND AND PURPOSE

Retrospective studies have suggested that routine stenting can be avoided following ureteroscopy. We prospectively analyzed the need for routine ureteral stent placement in patients undergoing ureteroscopic procedures.

PATIENTS AND METHODS

Fifty-five consecutive patients (60 renal units) were randomized into either a stent or a no-stent group following ureteroscopy with either a 7.5F semirigid or a 7.5F flexible ureteroscope for treatment of calculi (holmium laser or pneumatic lithotripsy) or transitional-cell carcinoma (holmium laser). Intraoperative variables assessed included total stone burden, the need for ureteral dilation, and overall operative times. All patients were evaluated by questionnaire on postoperative days 0, 1, and 6 with regard to pain, frequency, urgency, dysuria, and hematuria.

RESULTS

Of the 60 renal units treated, 38 received ureteral stents (mean 5.2 days), and 22 were treated without a stent. All 10 patients requiring ureteral balloon dilation had stents placed and were removed from the analysis. There was no significant difference between the groups with regard to age, sex, or stone burden. Operative time was decreased in the no-stent group (43 minutes v 55 minutes; P = 0.013). Flank discomfort was significantly less common in the no-stent group on days 0, 1, and 6 (P = 0.004, P = 0.003, P < 0.001, respectively), as was the incidence of suprapubic pain on day 6 (P = 0.002). There was no difference in urinary frequency, urgency, or dysuria between the groups on postoperative day 1, but all these symptoms were significantly reduced in the no-stent group on day 6 (P < 0.001, P < 0.001, P = 0.002, respectively). There was no significant difference in patient-reported postoperative hematuria in either group. One patient in each group developed a urinary tract infection. One patient in the no-stent group developed ureteral obstruction in the postoperative period that necessitated stenting, and one patient in the stent group experienced stent migration necessitating removal.

CONCLUSIONS

Routine ureteral stenting does not appear to be warranted in those patients who do not require ureteral dilation during ureteroscopic procedures. Ureteral stent placement following ureteroscopy may be avoided, thereby reducing operative time, surgical costs, and patient morbidity.

Ureteroscopy: current practice and long-term complications

PURPOSE

We compared a current cohort of patients who underwent ureteroscopy to a cohort from the early 1980s to determine changes in success, indications and long-term complications of the procedure.

MATERIALS AND METHODS

A chart review was performed of 194 patients who underwent 209 ureteroscopic procedures at our institution during 1992. This group was then statistically compared to 317 patients who underwent 346 ureteroscopies between 1982 and 1985.

RESULTS

The current indications for ureteroscopy were calculus extraction (67% of the cases), diagnosis (28%) and stent manipulation (5%). These indications differed from those of the early series, in which 84% of all ureteroscopies were performed for calculus extraction and 16% for diagnosis. Overall ureteroscopic success rate increased from 86 to 96% (p < 0.001). Success of stone extraction improved from 89 to 95% (p = 0.08, distal success rate 95 to 97% and proximal success rate 72 to 77%). Success of diagnostic inspections increased from 73 to 98% (p < 0.001). In the early series failure was usually due to inability to traverse the ureter (54% of the cases), while currently failure is due almost exclusively to impassable ureteral strictures (63%). The overall complication rate decreased from 20 to 12% (p = 0.01) and the rate of significant complications decreased from 6.6 to 1.5% (p < 0.05). Clinical followup (mean 36 months) for all patients and radiological followup (mean 9.8 months) for 67% of eligible patients detected only 1 ureteral stricture. The remaining patients were asymptomatic after the ureteroscopic procedure.

CONCLUSIONS

Improvements in ureteroscope design, accessories and technique have led to a significant increase in the success of diagnostic and therapeutic ureteroscopy while decreasing morbidity. Outpatient ureteroscopic stone extraction, particularly for distal ureteral calculi, is almost uniformly successful with low morbidity. The long-term complication rate of ureteroscopy is 0.5%.