Percutaneous nephrolithotomy under combined sonographic/radiologic guided puncture: results of a learning curve using the modified Clavien grading system

Aim of our study was to evaluate the results of percutaneous nephrolithotomy (PNL) with sonographic/fluoroscopic guided puncture during a learning curve and to compare them to an expert.

The first 75 consecutive patients undergoing conventional PNL or Mini-PNL by a novice percutaneous surgeon without direct supervision by an expert were evaluated and divided into three groups of 25 patients each. The results were compared to 50 cases treated by an expert.

For mean stone sizes of 22.3 ± 12.9, 22.7 ± 14.9, and 31.1 ± 25.5 mm, the OR-time was 124 ± 35, 106 ± 37, and 99 ± 31 min for the novice groups 1, 2, and 3, respectively. In contrast, the expert required an OR-time of 85 ± 28 min for a mean stone size of 19.7 ± 4.2 mm (p < 0.001; p < 0.01; n.s.). Stone free rates were 100, 96, and 100 %; however, second-look procedures were necessary in 24, 16, and 20 % of cases, whereas the expert needed only 8 % second-look procedures. No complications Clavien IIIb–V occurred. 16, 4, and 8 % of patients required a double-J placement (Clavien IIIa) due to hydronephrosis or urine leakage. One patient in the novice group 2 needed transfusion (Clavien II). Other minor complications (Clavien I) occurred in 28, 20 and 12 % in the novice groups 1, 2 and 3, respectively, in comparison with 22 % in the expert group.

Percutaneous stone treatment under combined sonographic/fluoroscopic guided puncture can be performed safe and efficiently during the learning curve. The lower expertise causes longer operation times and a higher re-intervention rate without compromising the patients’ safety.