Surgery · Medical Literature
Prevention of ureteral stone migration during percutaneous nephrolithotomy: a randomized controlled trial.
Abstract
With the increasing adoption of totally tubeless percutaneous nephrolithotomy (ttPCNL), prevention of stone fragment migration into the ureter has gained clinical importance. This study aimed to compare the incidence of ureteral fragment migration at the end of PCNL using a 5 Fr open-ended ureteral catheter (5FrUC) versus an occlusion balloon catheter (OBC). In this IRB-approved randomized controlled trial, 108 eligible patients were randomized 1:1 to either the 5FrUC or OBC group and 99 were included in the final analysis. The primary outcome, ureteral fragment migration, was defined as the presence of any stone fragment ≥ 1 mm between the ureteropelvic junction (UPJ) and ureterovesical junction (UVJ), confirmed by ureteroscopy at the conclusion of PCNL. Baseline demographics, stone characteristics, and operative parameters were comparable between groups, confirming effective randomization. Ureteral fragments were detected in 10 patients (10%): 7 with a single fragment, 2 with two fragments, and 1 with more than three fragments. The median fragment size was 2 mm (range, 1-4 mm). The incidence of ureteral fragments was significantly higher in the 5FrUC group compared with the OBC group (17% vs. 4%, p = 0.03). Logistic regression analysis demonstrated that OBC use reduced the risk of ureteral fragment migration by approximately 80% compared with 5FrUC (OR = 0.204, 95%CI 0.041-1.001, p = 0.05). Greater total stone burden, larger stone volume, higher Guy's stone score, and presence of full staghorn calculi were also associated with fragment migration. Use of an occlusion balloon catheter significantly reduced ureteral fragment migration compared with a 5 Fr open-ended ureteral catheter, achieving prevention in 96% of cases. Although the clinical impact of residual ureteral fragments remains uncertain, these findings support consideration of OBC use, particularly in ttPCNL procedures.
Clinical relevance
In patients undergoing percutaneous nephrolithotomy (PCNL), does an occlusion balloon catheter (OBC) reduce the incidence of intraoperative ureteral stone fragment migration compared with a standard 5 French open-ended ureteral catheter (5FrUC)? __SNAPSHOT__ {"studyDesign":"Randomized controlled trial (IRB-approved, 1:1 allocation)","setting":"Not reported in the available abstract excerpt; institutional affiliation consistent with Mount Sinai (Icahn School of Medicine) based on author registry data, but not explicitly confirmed in the abstract","sampleSize":"n=99 analyzed (5FrUC: ~50, OBC: ~49; exact per-arm n not reported in the available abstract); 108 patients randomized, 9 excluded post-randomization","population":"Adults (≥18 years) with kidney stones scheduled for PCNL; urinary tract anomalies (horseshoe kidney, solitary kidney, duplicated system, ureteropelvic junction obstruction, urinary stricture disease, previous ureteral reconstruction, urinary diversion, pelvic kidney, calyceal diverticulum stone) were excluded per registry data","intervention":"Occlusion balloon catheter (OBC) placed retrograde to occlude the ureteropelvic junction during PCNL","comparator":"5 French open-ended ureteral catheter (5FrUC) placed retrograde during PCNL","primaryOutcome":"Presence of any stone fragment ≥1 mm between the ureteropelvic junction (UPJ) and ureterovesical junction (UVJ), confirmed by ureteroscopy at the conclusion of PCNL","followUp":"Intraoperative only for primary outcome; postoperative follow-up duration not reported in available abstract","fundingSource":"Not reported"}
Key findings
Among 99 analyzed patients, ureteral fragment migration occurred in 10 patients overall (10% overall incidence). Of these, 7 had a single fragment, 2 had two fragments, and 1 had more than three fragments. The median fragment size was 2 mm (range 1–4 mm). The abstract states that the incidence of ureteral fragments was 'significantly higher' in one group versus the other, but the text is truncated before specifying which group had the higher rate, the exact per-group percentages, the between-group absolute risk difference, the relative risk or odds ratio, or the p-value. Accordingly, group-specific incidence rates, confidence intervals, p-values, NNT, and NNH cannot be reported and are labeled 'not reported' due to abstract truncation. No data on adverse events attributable to the OBC or 5FrUC were reported in the available abstract.
Practice implications
The study addresses a clinically relevant and increasingly important question in the era of totally tubeless PCNL (ttPCNL), where ureteral stents are omitted postoperatively and migrated intraoperative fragments may go undetected and cause subsequent obstruction, pain, or re-intervention. The abstract confirms successful randomization (balanced baseline demographics, stone characteristics, and operative parameters), and reports a statistically significant difference in fragment migration between the two catheter strategies. However, because the abstract is truncated, it is not possible to determine: (1) which catheter arm had the superior outcome; (2) the magnitude of the absolute or relative between-group difference; (3) whether the effect size is clinically meaningful; (4) whether any subgroup (e.g., stone burden, hydronephrosis grade, supine vs. prone positioning) drove the result; or (5) the safety profile of the OBC versus 5FrUC. Only abstract-level data were available for this summary, which is a critical limitation. Practice should not change on the basis of an incomplete abstract alone; the full publication must be reviewed before clinical application. __LIMITATIONS__ Abstract truncated — primary per-group outcome data, statistical test values (p-value, confidence intervals, odds ratio), and adverse event data are absent and cannot be evaluated.,Relatively small sample size (n=99) limits precision of effect estimates and may be underpowered to detect differences in rare secondary outcomes or subgroup effects.,Single-arm attrition of 9 patients post-randomization (108 enrolled → 99 analyzed) — reasons for exclusion and potential for differential exclusion bias are not reported.,Institutional setting not explicitly stated in the abstract; generalizability to lower-volume centers or varied surgical positions (prone vs. supine) is uncertain.,Ureteroscopic confirmation of the primary outcome at procedure end is methodologically rigorous but requires additional operative time and resource; whether this assessment was performed by blinded assessors is not reported.,The primary outcome is an intraoperative surrogate (fragment migration at end of case); downstream clinical outcomes (urinary obstruction, emergency department visits, re-intervention rates, stone-free rates at 30 days) are not reported.,Funding source and potential conflicts of interest are not reported, precluding assessment of sponsorship bias.,The patient population explicitly excluded numerous anatomic variants (horseshoe kidney, obstructed UPJ, etc.), limiting generalizability to anatomically complex cases.,Fragment size threshold of ≥1 mm may capture clinically insignificant findings that would pass spontaneously; clinical weighting of this definition is unclear without outcome data. __BOTTOM_LINE_CATEGORY__ low_certainty __BOTTOM_LINE__ This IRB-approved RCT compared OBC versus 5FrUC for prevention of intraoperative ureteral stone fragment migration during PCNL and reports a statistically significant difference between arms, with an overall migration incidence of 10% (median fragment size 2 mm). However, the abstract is truncated before disclosing which arm was superior, the magnitude of the effect, or p-values, making it impossible to assess clinical importance or guide practice at this time. Clinicians should await review of the full published manuscript before considering any change in intraoperative catheter selection strategy for ttPCNL.