Kidney STONE Score Calculator for PCNL

Your details

Maximum diameter of the stone (or stone aggregate) on CT in millimetres.
mm
Perpendicular diameter of the stone on CT. Stone size = length x width.
mm
Distance from the centre of the stone to the skin surface on CT, measured at 0 degrees, 45 degrees, and 90 degrees. Use the shortest of the three.
mm
Degree of pelvicalyceal dilatation seen on CT. None/mild scores 1; moderate/severe scores 2.
Number of distinct calyceal groups containing stone material. A staghorn stone filling the entire pelvicalyceal system scores 3.
Mean CT attenuation of the stone in Hounsfield units. Stones at 950 HU or below score 1; denser stones (often calcium oxalate monohydrate or brushite) score 2.
HU
STONE ScoreLow complexity
5

Total STONE nephrolithometry score (5 = easiest, 13 = most complex)

Predicted stone-free rate94%
Stone area300mm²
S - Stone size points1
T - Tract length points1
O - Obstruction points1
N - Calyces points1
E - Density points1
5 pts
Low complexity<8Moderate complexity8-10High complexity10+

STONE score 5 - low-complexity stone, predicted 94% stone-free rate after PCNL.

  • Stone area: 300 mm² (20 × 15 mm), contributing 1 point to the total.

Next stepA score of 7 or below corresponds to a predicted stone-free rate of 88% or higher. Standard single-tract PCNL is likely to achieve complete clearance in the first session.

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