Smith et al reported a nomogram for predicting the success of percutaneous nephrolithotomy (PCNL). This can help to identify a patient who may require additional therapy. The authors are from Long Island Jewish Medical Center, University of Pittsburgh, University of Toledo, Academic Medical Center University Hospital in Amsterdam, Ege University in Izmir (Turkey) and Hospital Italiano in Buenos Aires.
Patient selection: nephrolithiasis
Stone free was defined as either having no residual stone fragments OR residual fragments less than 4 mm in diameter.
Parameters:
(1) stone burden in square millimeters
(2) stone location
(3) prior treatment
(4) staghorn calculus
(5) number of stones
(6) case volume per year
points for stone burden =
= MAX(0,(-0.0655 * (burden)) + 78.6)
|
Case Volume |
Likelihood Stone Free |
|
0 to 140 |
|
|
140 to 160 |
100 |
|
160 to 300 |
(-0.001601 * ((cases)^2)) + (0.334 * (case)) + 88.16 |
|
> 300 |
45 |
|
Parameter |
Finding |
Points |
|
stone location |
upper |
10 |
|
|
lower |
45.5 |
|
|
pelvic |
58.2 |
|
|
middle |
69.6 |
|
|
multiple |
0 |
|
prior treatment |
none |
37.3 |
|
|
multiple |
3.3 |
|
|
PCNL |
17 |
|
|
ureterorenoscopic |
18.6 |
|
|
extracorporeal shock wave |
19 |
|
staghorn |
yes |
0 |
|
|
no |
20.3 |
|
number of stones |
single |
34 |
|
|
multiple |
0 |
total score =
= SUM(points for all 6 parameters)
Interpretation:
• minimum score: 0
• maximum score: 350
• The higher the score the greater the likelihood of being stone free after PCNL.
|
Score |
Likelihood Stone Free |
|
< 22 |
< 30% |
|
22 to 220 |
(-0.000591 * ((score)^2)) + (0.4552 * (score)) + 19.22 |
|
> 220 |
> 90% |
Specialty: Nephrology, Clinical Laboratory
ICD-10: ,
