Predicting the success of retrograde stenting for managing ureteral obstruction

Purpose: Retrograde ureteral stenting is often considered the first line op tion for relieving ureteral obstruction when temporary drainage is indicate d. Several retrospective studies have implied that in cases of extrinsic ob struction retrograde ureteral stenting may fail and, therefore, percutaneou s nephrostomy drainage is required. We examined the efficacy of retrograde ureteral stenting for resolving ureteral obstruction and identified clinica l and radiological parameters predicting failure. Materials and Methods: Enrolled in our prospective study were 92 consecutiv e 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 vis it included a medical interview, blood evaluation, urine culture and ultras ound. Stent malfunction was defined as continuous flank pain manifesting as recurrent episodes of acute renal colic, 1 or more episodes of pyelonephri tis, persistent hydronephrosis or elevated creatinine. Preoperative data an d outcomes were compared in cases of intrinsic and extrinsic obstruction. U nivariate 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 e xtrinsic in 39%. Extrinsic obstruction, which was associated with a greater degree of hydronephrosis, was located more distal. Retrograde ureteral ste nting was successful in 94% and 73% of patients with intrinsic and extrinsi c obstruction, respectively. At the 3-month followup stent function was mai ntained in all patients with intrinsic obstruction but in only 56.4% with e xtrinsic obstruction. On multivariate logistic regression the type of obstr uction, level of obstruction and degree of hydronephrosis were the only pre dictors of stent function at 3 months. Stent diameter and preoperative crea tinine had no predictive value. Conclusions: Retrograde ureteral stenting is a good solution for most acute ly obstructed ureters. In patients with extrinsic ureteral obstruction a mo re distal level of obstruction and higher degree of hydronephrosis are asso ciated with a greater likelihood of stent failure. These patients may be be tter served by percutaneous drainage.