Determinants of ureteral obstruction after percutaneous nephrolithotomy

Abstract

Background Ureteral obstruction after percutaneous nephrolithotomy (PCNL) may require prolonged drainage with a nephrostomy tube (NT) or ureteral stent, but it is not well understood how and why this occurs. The goal of this study was to identify risk factors associated with postoperative ureteral obstruction to help guide drainage tube selection. Methods Prospective data from adult patients enrolled in the Registry for Stones of the Kidney and Ureter (ReSKU) who underwent PCNL from 2016 to 2020 were used. Patients who had postoperative NTs with antegrade imaging-based flow assessment on postoperative day one (POD1) were included. Patients with transplanted kidneys or those without appropriate preoperative imaging were excluded. We assessed the association between patient demographics, stone characteristics, and intraoperative factors using POD1 antegrade flow, a proxy for ureteral patency, as the primary outcome. Stepwise selection was used to develop a multivariate logistic regression model controlling for BMI, stone location, stone burden, ipsilateral ureteroscopy (URS), access location, estimated blood loss, and operative time. Results We analyzed 241 cases for this study; 204 (84.6%) had a visual clearance of stone. Antegrade flow on POD1 was absent in 76 cases (31.5%). A multivariate logistic regression model found that stones located anywhere other than in the renal pelvis (OR 2.63, 95% CI 1.29–5.53; p = 0.01), non-lower pole access (OR 2.81, 95% CI 1.42–5.74; p < 0.01), and concurrent ipsilateral URS (OR 2.17, 95% CI 1.02–4.65; p = 0.05) increased the likelihood of obstruction. BMI, pre-operative stone burden, EBL, and operative time did not affect antegrade flow outcomes. Conclusion Concurrent ipsilateral URS, absence of stones in the renal pelvis, and non-lower pole access are associated with increased likelihood of ureteral obstruction after PCNL. Access location appears to be the strongest predictor. Recognizing these risk factors can be helpful in guiding postoperative tube management.

Transient ureteral obstruction after mini-percutaneous nephrolithotomy is associated with stone volume and location: results from a single-center, real-life study

“…In our study, 20% of patients treated with mPCNL showed ureteral obstruction during percutaneous pyelography on POD2. This rate is lower compared to that reported in a series of 241 standard PCNL, in which Authors found that 31.5% of patients had impaired ureteral canalization on POD1 [ 7 ]. Our results might differ from those in published literature for several reasons.…”

“…Nonetheless, early postoperative complications can occur even after uneventful mPCNL, thus neutralizing the advantages of a tubeless procedure or an early discharge [ 17 ]. Among these, transient upper urinary tract obstruction due to post-PCNL edema, in patients without urinary drainage, can cause severe pain, kidney function impairment, and hospital readmission [ 7 ]. For this reason, it is of primary clinical importance to identify patients at higher risk of ureteral obstruction, in order to improve the selection of totally tubeless mPCNL procedures.…”

“…Our results might differ from those in published literature for several reasons. First, Lee et al [ 7 ] investigated antegrade flow by fluoroscopic antegrade nephrostogram, contrast-enhanced ultrasound, or methylene blue dye test. By using different tests, it is possible that the rate of ureteral obstruction might be different.…”

“…Transient ureteral obstruction after PCNL is more common, and it is primarily caused by intraoperative tissue manipulation causing local edema [ 7 ]. Several factors might be associated with intraoperative tissue damage and ureteral obstruction.…”

“…Conversely, the most frequently reported reason for transient post-PCNL urinary obstruction is local edema, due to the presence of impacted stones and mechanical trauma that occurred during the procedure and intracorporeal lithotripsy [ 5 ]. In addition to these factors, concurrent ipsilateral ureteroscopy, stone location, and type of surgical access could also contribute to a transient lack of ureteral canalization after PCNL [ 7 ]. To avoid obstructive complications, an indwelling ureteral stent is commonly placed as an exit strategy after standard procedures [ 8 ].…”