LIKELIHOOD OF RETROGRADE DOUBLE-J STENTING ACCORDING TO URETERAL OBSTRUCTING PATHOLOGY

Objectives: To evaluate the likelihood of retrograde double-J stenting in urgent ureteral drainage according to obstructing pathology. Materials and Methods: From July 2002 to January 2003, 43 consecutive patients with ureteral obstruction who needed urgent decompression were evaluated at our institution, where we performed a total of 47 procedures. Emergency was defined as ureteral obstruction associated with infection, obstructive acute renal failure, or refractory pain. Ureteral obstruction was defined as intrinsic and extrinsic based on etiology and evaluated by ultrasound. Patients submitted to previous double-J stenting were excluded. Failures in retrograde ureteral stenting were treated with percutaneous nephrostomy. Results were analyzed with Fisher’s exact test and regression analysis. Results: Failure in retrograde ureteral stenting occurred in 9% (2/22) and 52% (13/25) of the attempts in patients with intrinsic and extrinsic obstruction respectively (p < 0.001). Failures in stenting extrinsic obstructions occurred due to lack of identification of the ureteral meatus in 77% and impossibility of catheter progression in 23% (p < 0.05). All attempts of retrograde catheter insertion failed in obstructions caused by prostate or bladder pathologies (6/6). Inability to identify the ureteral meatus was the cause of all failures. Conclusion: Retrograde double-J stenting has a low probability of success in extrinsic ureteral obstruction caused by prostate or bladder disease. Such cases might be best managed with percutaneous nephrostomy.


INTRODUCTION
Ureteral obstruction often presents as urological urgency demanding surgical treatment with urinary diversion (1)(2)(3)(4)(5).The first successful endoscopic ureteral drainage using a silicone catheter was reported by Zimskind et al. in 1967 (6).During the last decade, double-J stenting has been widely used by urologists.Despite endourological technical advances, retrograde double-J stenting may be cum-bersome or impossible.Alternatively, one may prefer percutaneous nephrostomy, an efficient method but with the inconvenience of being an external diversion (1)(2)(3)(4)(5)7,8).The choice of double-J stenting or percutaneous nephrostomy for urgent ureteral decompression is controversial and oriented by surgeon preference (4).There are a few studies on this issue and most of them are retrospective involving elective procedures (1,2,5,(7)(8)(9).We conducted a prospective study to evaluate the success of retrograde double-J stenting in urgent ureteral drainage and to define criteria for selection of decompression method in order to reduce cost and to avoid time loss.

MATERIALS AND METHODS
Between July 2002 and January 2003, 43 consecutive patients with ureteral obstruction and need of urgent decompression were evaluated at our institution, where we performed a total of 47 procedures.The need for urgent decompression was defined as ureteral obstruction associated with infection, obstructive acute renal failure, or refractory pain.All patients were evaluated with x-ray (KUB) and ultrasound in order to diagnose obstructive uropathy (10).Non-enhanced spiral CT was performed when standard evaluation was not satisfactory.Patients submitted to previous retrograde double-J stenting were excluded.
All procedures were performed under general anesthesia, with fluoroscopic C-arm guidance (13).Retrograde pyelography was performed previously to each procedure when it was possible to identify the ureteral meatus.This was done using an openended ureteral catheter.This catheter was then used to pass a 0.35 mm hydrophilic guide wire (13).A nonhydrophilic polyurethane double-J ureteral catheter of various sizes (4,7;6;7 Fr) was used according to surgeon's preference (14,15).
The adequate positioning of the double-J stent was confirmed by fluoroscopy at the end of the procedure.Failures in retrograde ureteral stenting were immediately treated with percutaneous nephrostomy.The percutaneous nephrostomy kit used was 14F/4.6 mm.The success of percutaneous nephrostomy placement was confirmed with antegrade pyelography after the procedure.
Statistical analysis was performed with Fisher's exact test and regression analysis, with p < 0.05 considered significant.

RESULTS
Intrinsic and extrinsic lesions were responsible for 47% and 53% of the obstructions respectively (Table -1).
The need for ureteral decompression differed between groups.The main indication for decompression in the intrinsic group was pyelonephritis (77%) and in the extrinsic group it was acute renal failure (88%).The site of obstruction was preferentially distal in extrinsic lesions, and proximal in intrinsic ones (84% vs. 41%, p < 0.001), and renal dilation was more pronounced in the extrinsic group (27% vs. 44%, p < 0.05).
The results show that retrograde ureteral stenting success was significantly lower in patients with extrinsic ureteral obstruction (Table -5).
Retrograde ureteral stenting failures in intrinsic obstruction were caused by non-progression of the hydrophilic guide wire and by non-identification of the ureteral meatus (one case each).Failures in extrinsic obstruction were caused by non-progression of the hydrophilic guide wire in 3 patients (23%) and by non-identification of the ureteral meatus in 10 patients (77%) (p < 0.05).All attempts of catheter insertion failed in obstructions caused by prostate or bladder pathologies (Table -6).Inability to identify the ureteral meatus was the cause of all failures.
One retrograde double-J insertion became complicated with ureteral perforation distally to the extrinsic obstruction and was managed with percutaneous nephrostomy.Follow-up was uneventful.

COMMENTS
The cornerstone for acute ureteral obstruction treatment is ureteral decompression.The ideal method should be minimally invasive, fast, and inexpensive.Currently, the most common methods in these situations are insertion of double-J catheter or placement of percutaneous nephrostomy.There is no consensus in the literature about which one is more appropriate, and usually the choice is left to the surgeon's preference (4).We evaluate the urgent ureteral decompression in patients with ureteral obstruction due to intrinsic and extrinsic pathologies.Retrograde double-J stenting failed in 9% (2/22) of intrinsic obstruction and in 52% (13/25) of extrinsic obstruction (p < 0.001).Yossepowitch and coworkers had a similar success index in patients with intrinsic ureteral obstruction and higher success index in selected cases of extrinsic obstruction (1).When the ureteral meatus was identified, retrograde pyelography was performed previously to each procedure.It did not alter the previous diagnosis of intra-or extra-ureteral obstruction, nevertheless it was useful to the detection of unexpected ureteral kinking.Failures of retrograde catheter insertion in extrinsic obstruction occurred due to non-identification of the ureteral meatus in 77% of the cases.Identification of ureteral meatus in patients with lower urinary tract conditions such as prostate and bladder pathologies was not possible in 100%  of cases.Therefore, attempts of retrograde catheter insertion in patients with lower urinary tract conditions may be avoided, giving preference to percutaneous nephrostomy.
Pearle and associates concluded that double-J catheter and percutaneous nephrostomy are equally good methods for ureteral decompression in obstruc- tive ureterolithiasis associated with infection (7).However, double-J catheters are prone to obstruct when used for long periods.Docimo & DeWolf reported a 30-day re-obstruction index up to 53% in extrinsic ureteral obstruction (9).Such problem may be adequately dealt with by simultaneous insertion of 2 double-J catheters in the obstructed ureteral unit (4,11,12).
The impact in quality of life caused by temporary urinary diversion was accessed by Joshi & colleagues and no functional or psychosocial difference between double-J catheter and percutaneous nephrostomy in ureteral decompression was found (5).Nevertheless, patients were followed for only 30 days.Possibly a longer follow-up may disclose differences between both methods.Our impression is that an external prosthesis promotes progressive loss of quality of life caused by more hospital visits due to nephrostomy displacement or infection.
The choice of ureteral drainage method should take cost into account.Both procedures are expensive as they are performed in the operating room under fluoroscopy.The double-J catheter used in the present study costs US$ 47 and the percutaneous nephrostomy kit costs US$ 88.As the double-J catheter ensures adequate ureteral drainage, similar impact in quality of life and lower cost, it should be considered the preferential method for ureteral decompression except for selected cases.

CONCLUSIONS
Retrograde double-J stenting has a low probability of success in extrinsic ureteral obstruction caused by prostate or bladder disease.Such cases might be best managed with percutaneous nephrostomy.

EDITORIAL COMMENT
Double-J stenting has become an important endourological procedure in ureteral obstructive pathology.Successful stenting would reduce the morbidity of extrinsic ureteral obstruction.The authors reported a low success rate, especially in lower ureteral obstruction due to bladder or prostate pathology.Deployment of metallic ureteral stents would be a solution for overcoming the obstruction in this situation.Success would depend upon passing a guide wire.Failures in the retrograde approach can be overcome by antegrade stenting under ultrasound guided and fluoroscopic control.The upper tracts are usually dilated and easy to puncture.The guide wire can be negotiated into the bladder by using an angiogra-phy curved tip catheter.Once the guide wire is in the bladder it can be pulled outside the urethra by cystoscopy.By pulling the guide wire in the opposite direction the curvatures can be straightened out, making it easy to dilate over which one can put either double-J stent or metallic stent.
In my experience, combining an antegrade and retrograde approach to ureteral obstruction success can be increased remarkably.

Table 1 -
Specific causes of ureteral obstruction in 47 kidneys.

Table 2 -
General data of the patients with intrinsic ureteral obstruction.

Table 3 -
General data of the patients with extrinsic ureteral obstruction.

Table 5 -
Success index of double-J insertion between groups.

Table 4 -
Demographic data of intrinsic and extrinsic obstruction cases.

Table 6 -
Success index of double-J insertion versus type of disease causing extrinsic ureteral obstruction.