Management of Small Urinary Stones (≤5 mm)
First-Line Recommendation
For a patient with a small urinary stone ≤5 mm and controlled symptoms, observation with medical expulsive therapy (MET) using alpha-blockers is the recommended first-line approach. 1, 2
Initial Management Strategy
Observation with MET
- Stones <5 mm have approximately 68% chance of spontaneous passage, with most passing within 17 days (range 6-29 days) 1
- Alpha-blocker therapy increases stone passage rates by 29% and should be offered to all appropriate candidates 1, 2
- Patients must have well-controlled pain, no clinical evidence of sepsis, and adequate renal functional reserve to be candidates for conservative management 3
- Counsel patients that MET is "off-label" use and discuss associated drug side effects 3
Pain Management
- NSAIDs (diclofenac, ibuprofen, metamizole) are first-line for renal colic pain if it develops 2
- Adequate analgesia is mandatory during the observation period 4
Monitoring Requirements
Imaging Follow-up
- Perform periodic imaging studies (preferably low-dose CT or ultrasound) to monitor stone position and assess for hydronephrosis 3, 2
- Follow-up imaging every 6 months is reasonable for asymptomatic stones 5
- If symptoms change, repeat imaging should be obtained as stone position may influence treatment 2
Duration of Conservative Management
- Maximum duration for conservative management should be limited to 4-6 weeks from initial presentation to avoid irreversible kidney injury 2
- If observation with or without MET is unsuccessful after 4-6 weeks, definitive stone treatment should be offered 2
Indications for Immediate Intervention
Intervention is warranted if any of the following develop:
- Uncontrolled pain despite adequate analgesia 1, 2
- Signs of infection or sepsis 1, 2
- Development of obstruction or hydronephrosis 1, 2
- Inadequate renal function 1
Intervention Options When Required
Ureteroscopy (URS)
- URS has the highest stone-free rate (90-95%) in a single procedure for stones <10 mm 3, 2
- More invasive with higher complication rates including 3-6% ureteral injury risk 3
- Stricture rates of 1-4% depending on stone location 3
Shock Wave Lithotripsy (SWL)
- SWL has success rates of 80-85% with the least morbidity and lowest complication rate 3, 2
- May require repeat procedures due to lower single-procedure stone-free rates (72%) 2
- Routine stenting is not recommended as part of SWL 3
- Sepsis rates of 2-5% depending on stone location 3
Treatment Selection
- Both URS and SWL are acceptable first-line treatments when intervention is required 3
- URS provides higher likelihood of stone clearance in a single procedure, while SWL has lower morbidity 2
- Patients must be informed about stone-free rates, anesthesia requirements, need for additional procedures, and associated complications for both modalities 3
Critical Pitfalls to Avoid
- Never perform blind stone basketing without endoscopic visualization - this carries obvious risk of ureteral injury 3
- Do not continue observation indefinitely beyond 4-6 weeks - prolonged obstruction can lead to irreversible kidney damage 2
- Always obtain urine culture prior to intervention - untreated bacteriuria can lead to urosepsis when combined with obstruction or endourologic manipulation 3
- Administer appropriate antibiotic therapy before intervention if infection is suspected or proven 3
Special Considerations
Stone Composition
- For uric acid stones, offer oral chemolysis with alkalinization (citrate or sodium bicarbonate to achieve pH 7.0-7.2) with 80.5% success rate 2, 4
- Send stone material for analysis if retrieved to guide prevention strategies 2
Recurrence Prevention
- Risk of second stone is 50% within 5-7 years after the first stone 2
- Obtain 24-hour urine collection for metabolic evaluation in recurrent stone formers 2