Preoperative factors associated with failure in unstented primary ureteroscopy for nephrolithiasis

Primary ureteroscopy for nephrolithiasis is often completed without prior ureteral stenting. However, failure can occur due to inability to access the stone, requiring ureteral stenting for passive dilation and a second procedure. This typically results in increased morbidity due to a prolonged period of ureteral stenting and subsequent stent related symptoms. Patient counseling preoperatively is important to discuss the risk of failure.

We reviewed all primary ureteroscopies for nephrolithiasis performed by four urologists at our institution from November 2007 to November 2016. Univariate analysis was performed to compare groups with Chi squared analysis, Fisher's exact test, Student's t-tests and Mann-Whitney U test as appropriate. Binomial logistic regression was then performed analyzing the statistically significant univariate factors.

Failure rate for accessing the unstented ureter was 6.04% (30/497). Thirty ureteroscopies were identified who failed without prior ureteral stenting. A total of 422 ureteroscopies were identified with successful initial attempt with records complete for analysis. Failures were more likely to have a proximal ureteral stone (46.6% versus 23.9%). This remained significant on logistic regression. There was no difference in stone size, number of stones, age, sex, history of stones, prior abdominal or retroperitoneal surgery. Failure of primary ureteroscopy in women was associated with proximal stones (50.0% versus 20.9%) and women with a prior hysterectomy and/or oophorectomy (67.0% versus 32.0%). Both remained significant on logistic regression. Men did not have any significant factors.

The vast majority of ureteroscopy is performed without prior ureteral stenting. Proximal ureteral stones appear to be the only factor associated with failure in primary ureteroscopy. Additionally, one may consider counseling women with prior hysterectomy and/or oophorectomy that they may be at increased risk of requiring a second procedure.