S.T.O.N.E. nephrolithometry (PCNL complexity)
S.T.O.N.E. nephrolithometry (Okhunov 2013): a 5-13 PCNL complexity score (original area version) from stone size (area), tract length, obstruction, involved calices, and stone density.
Open the calculator → Runs in your browser. Data leaves only if you deliberately send a problem report from the interactive tool.
Example
- Stone length
- 20 mm
- Stone width
- 20 mm
- Tract length, skin to stone
- 80 mm
- Obstruction
- None / mild (1)
- Number of involved calices
- 1–2 calices (1)
- Stone density
- 800 HU
Result: S.T.O.N.E. 6 of 13 (stone area 400 mm^2) -- low complexity; higher scores carry a lower PCNL stone-free likelihood (low 5-6, moderate 7-8, high >=9).
The tool opens with these values already filled in. Replace them with your own.
What the result means
- 5-6
- Low PCNL complexity; the highest stone-free likelihood.
- 7-8
- Moderate complexity.
- >=9
- High complexity; a lower stone-free likelihood. A higher total means a harder case.
What you enter
- Stone length
- Stone width
- Tract length, skin to stone
- Obstruction (hydronephrosis)
- Number of involved calices
- Stone density
How this is calculated
Okhunov Z, Friedlander JI, George AK, et al. S.T.O.N.E. nephrolithometry: novel surgical classification system for kidney calculi. Urology. 2013;81(6):1154-1159. Read the source ↗
A reference and educational tool. Not medical, legal, or financial advice, and not a substitute for clinician judgment.