[Learning of percutaneous nephrolithotomy in supine position. An observational multicenter study].

OBJECTIVE To prospectively study the post-operative results and complications of percutaneous nephrolithotomy (PNL) in supine position to assess difficulty of learning it and how experience affects the results. To establish a relative comparison with the data published in the literature on the prone position. MATERIAL AND METHODS A prospective observational multicenter study on PNL in Valdivia position or in its Galdakao variant was performed. Demographic variables and specific variables related to the lithiasis were collected. Technical aspects, surgery time, success rate and complications according to the Clavien-Dindo classifications were assessed. RESULTS A total of 335 PNL in supine position conducted in 13 Spanish centers were registered from September 2008 to June 2011. The man:woman ratio was 1:1.28 and mean age 51.3+14.5 years. 211 (63%) cases were performed by urologists with experience in >50 cases and 124 (37%) by urologists with less experience. Mean operation time was 113.3 ± 46.4 min, 106.6 ± 38.2 for the experienced ones vs. 124.9 ± 56.2 in the novice ones (P<.002). No difference was detected in the mean size of the lithiasis. However, in the experienced group, there was a greater proportion of coraliform cases and multiple lithiasis than in the novice group (P<.001). Success rate evaluated as total absence of lithiasic residuals was 69.6%, without differences between groups (68.2 vs. 71.8%). In 102 (30.6%) patient had residual lithiasis and 60 (17,9%) required complementary treatment. Relative global success rate was 82.1% and complications rate 25.4%, without detecting differences between groups. However, the novel group had more major complications (P>.001). CONCLUSION The PNL in supine position is obtaining rapid and consolidated diffusion in our setting and its effectiveness and safety seems to be equivalent to that described in the literature for PNL in prone position. It is possible to obtain good results with a modest learning curve. The rate of greater complications associated to the procedure decreases with experience.