Study population is estimated basing on previous studies of major complications after CNBs, which indicate an incidence of major adverse effects of 4.2 on 100.000 patients. Estimating an incidence of 1:25.000, a number of 25.000 procedures was calculated to be needed for the study, with a confidence interval of 95%. The primary endpoint was to assess cumulative incidence of adverse effects, while a following case-control analysis will be performed to identify possible risk factors.