Is a 1.1 cm kidney stone small enough to pass on its own?

A 1.1 cm (11 mm) Kidney Stone is Too Large to Pass Spontaneously and Requires Surgical Intervention

A kidney stone measuring 1.1 cm (11 mm) will not pass on its own and requires active surgical treatment. The evidence clearly demonstrates that stones larger than 10 mm have extremely low spontaneous passage rates and should not be managed with observation alone.

Why This Stone Won't Pass

• Stones ≤10 mm are the cutoff for potential spontaneous passage, and your 1.1 cm stone exceeds this threshold 1.
• The American Urological Association guidelines specifically state that observation with medical expulsive therapy is only appropriate for uncomplicated ureteral stones ≤10 mm 1.
• Stone size directly correlates with passage rates—the larger the stone, the lower the likelihood of spontaneous passage 1.
• Even with medical expulsive therapy using alpha-blockers, which increases passage rates for smaller stones, stones >10 mm require surgical intervention 1, 2.

Recommended Treatment Approach

First-Line Surgical Options

The treatment depends on stone location, but for an 11 mm stone:

For stones in the kidney (renal stones):

• Ureteroscopy (URS) should be offered as first-line therapy, with stone-free rates of approximately 75-95% for stones in this size range 1, 2.
• Percutaneous nephrolithotomy (PCNL) may be considered for complex cases, though it's typically reserved for stones >20 mm 1.
• Shock wave lithotripsy (SWL) should NOT be used as first-line therapy for stones >10 mm, as success rates are significantly lower and multiple treatments are often required 1.

For stones in the ureter:

• URS is the preferred approach with high success rates 1.
• SWL may be considered but has lower stone-free rates compared to URS for stones of this size 1.

Important Clinical Pitfalls

• Do not attempt prolonged observation beyond 4-6 weeks, as this can lead to irreversible kidney damage from chronic obstruction 2.
• Urgent intervention is mandatory if any of the following develop: uncontrolled pain despite adequate analgesia, signs of infection or sepsis, or progressive hydronephrosis 1, 2.
• If infection is suspected with obstruction, the collecting system must be urgently drained with a ureteral stent or nephrostomy tube before definitive stone treatment 1.

What to Expect with Treatment

• URS provides the highest single-procedure stone-free rate (90-95%) but is more invasive than SWL 2.
• SWL has lower morbidity but stone-free rates drop significantly for stones >10 mm (approximately 73-78% for pediatric data, likely similar in adults) 1.
• Multiple procedures may be needed depending on the treatment chosen—URS typically requires fewer repeat procedures than SWL 1.

Why Medical Management Alone Won't Work

• Medical expulsive therapy with alpha-blockers increases passage rates by approximately 29% only for stones ≤10 mm 2.
• The meta-analysis from AUA guidelines showed superior stone-free rates with alpha-blockers (77.3%) versus placebo (54.4%) specifically for distal ureteral stones <10 mm 1.
• Your 11 mm stone is beyond the size threshold where medical therapy provides benefit 1, 2.

Next Steps

• Consult urology promptly for surgical planning 1.
• Ensure adequate pain control with NSAIDs (diclofenac, ibuprofen) as first-line agents if renal colic develops 2.
• Obtain urine culture before any intervention to rule out infection 1.
• Consider metabolic evaluation after stone removal, as recurrence risk is 50% within 5-7 years 2.
• Send retrieved stone material for analysis to guide future prevention strategies 2.