What are the long-term implications of stone intrusion and extrusion during ureteroscopic lithotripsy?

Long-Term Implications of Stone Intrusion and Extrusion During Ureteroscopic Lithotripsy

The long-term complications of ureteroscopic stone treatment are minimal, with stricture formation occurring in 2% or less of cases and ureteral perforation rates reduced to less than 5%, making modern ureteroscopy a safe procedure with excellent long-term outcomes. 1

Understanding Stone Migration During URS

During ureteroscopic lithotripsy, stones may migrate proximally into the kidney (intrusion/retropulsion) or fragments may be pushed through the ureteral wall (extrusion). The evidence addresses these scenarios differently:

Stone Retropulsion (Proximal Migration)

When stones migrate proximally during ureteroscopy, conversion to flexible ureteroscopy is the standard approach and does not compromise long-term outcomes. 2

• Stone migration to the kidney occurred in 51 cases during rigid ureteroscopy for large stones, successfully managed by converting to flexible lithotripsy without adverse long-term sequelae 2
• The flexible ureteroscope achieves superior stone-free rates (87%) compared with rigid ureteroscopy (77%) for proximal stones, making this conversion beneficial rather than problematic 1
• Overall stone-free rates for ureteroscopic treatment remain remarkably high at 81% to 94% depending on stone location, regardless of whether conversion was needed 1

Ureteral Perforation and Stone Extrusion

Ureteral perforations, including those with extra-ureteric stone fragments, typically heal without serious long-term consequences, though they may prolong initial hospitalization. 3

• Perforation occurred in 14% of ureteroscopic cases, usually trivial and near the vesicoureteric junction 3
• Higher ureteral perforations following endoscopic lithotripsy were occasionally associated with urinary extravasation and extra-ureteric stone fragments 3
• Critically, there were no serious sequelae from these perforations, though in-patient stay was prolonged beyond the customary 48 hours 3
• Modern complication rates show ureteral perforation reduced to less than 5% with current techniques 1

Long-Term Structural Outcomes

The risk of long-term ureteral stricture formation following ureteroscopy is 2% or less, representing the primary structural concern. 1

• This low stricture rate applies across all ureteral locations and stone sizes 1
• The development of smaller caliber semirigid and flexible ureteroscopes with improved instrumentation (particularly the holmium:YAG laser) has contributed to these excellent long-term outcomes 1

Stone Recurrence Considerations

The technique used for stone treatment (dusting vs. fragmentation with extraction) may influence long-term stone recurrence risk, though both approaches are effective. 4

• Dusting techniques may place patients at increased risk for future stone events if all resultant debris is not expelled from the collecting system 4
• Fragmentation with extraction provides more complete initial stone clearance, potentially reducing recurrence risk 4
• For infection-related stones specifically, the 5-year recurrence risk is 36.8%, with anatomical abnormalities being the primary risk factor rather than the surgical technique itself 5

Common Pitfalls to Avoid

Do not assume that stone fragments left in the collecting system are benign—they can serve as nidi for future stone formation. 4

• When using dusting techniques, ensure adequate fragment clearance or accept the trade-off of potentially higher recurrence rates 4
• Patients with anatomical abnormalities require continued surveillance regardless of initial stone-free status, as they face significantly higher recurrence rates 5

Do not delay definitive treatment of perforations with significant extravasation—though long-term outcomes are good, acute management matters. 3

• Perforations with urinary extravasation require prolonged monitoring but typically resolve without intervention 3
• The vast majority of patients are rendered stone-free in a single procedure despite these complications 1

Quality of Life Implications

Long-term quality of life following ureteroscopy is excellent, with the procedure avoiding the potential chronic effects associated with shock wave lithotripsy. 6

• SWL can cause vascular trauma leading to scarring with permanent loss of functional renal volume and has been linked to potentially serious long-term adverse effects including diabetes mellitus 6
• Ureteroscopy avoids these systemic complications, making it preferable from a long-term morbidity standpoint 6