Predicting the success of retrograde stenting for managing ureteral obstruction

Purpose: Retrograde ureteral stenting is often considered the first line option for relieving ureteral obstruction when temporary drainage is indicated. Several retrospective studies have implied that in cases of extrinsic obstruction retrograde ureteral stenting may fail and, therefore, percutaneous nephrostomy drainage is required. We examined the efficacy of retrograde ureteral stenting for resolving ureteral obstruction and identified clinical and radiological parameters predicting failure. Materials and Methods: Enrolled in our prospective study were 92 consecutive patients with ureteral obstruction, which was bilateral in 8. Retrograde ureteral stenting was attempted in all cases by the urologist on call. When stent insertion failed, drainage was achieved by percutaneous nephrostomy. Patients were followed at 3-week intervals for 3 months. Each followup visit included a medical interview, blood evaluation, urine culture and ultrasound. Stent malfunction was defined as continuous flank pain manifesting as recurrent episodes of acute renal colic, 1 or more episodes of pyelonephritis, persistent hydronephrosis or elevated creatinine. Preoperative data and outcomes were compared in cases of intrinsic and extrinsic obstruction. Univariate and multivariate analysis was done to identify predictors of the failure of ureteral stent insertion and long-term function. Results: The etiology of obstruction was intrinsic in 61% of patients and extrinsic in 39%. Extrinsic obstruction, which was associated with a greater degree of hydronephrosis, was located more distal. Retrograde ureteral stenting was successful in 94% and 73% of patients with intrinsic and extrinsic obstruction, respectively. At the 3-month followup stent function was maintained in all patients with intrinsic obstruction but in only 56.4% with extrinsic obstruction. On multivariate logistic regression the type of obstruction, level of obstruction and degree of hydronephrosis were the only predictors of stent function at 3 months. Stent diameter and preoperative creatinine had no predictive value. Conclusions: Retrograde ureteral stenting is a good solution for most acutely obstructed ureters. In patients with extrinsic ureteral obstruction a more distal level of obstruction and higher degree of hydronephrosis are associated with a greater likelihood of stent failure. These patients may be better served by percutaneous drainage.