The mean Qmax for 46 patients without preoperative urinary retention increased from 7 ± 4.04 (2.5 - 19) mL / s before to 16.71 ± 5.36 (6.8 - 28) mL / s after vaporesection and Qmax for 39 patients with preoperative urinary retention or unable measured 15.24 ± 4.24 (6.8 - 24) after vaporesection.