No randomised studies were identified. One of the non-randomised, comparative studies looking at laparoscopic pyeloplasty versus open pyeloplasty found that 41 out of 42 patients (98%) who had the laparoscopic procedure had no obstruction at follow-up, compared with 33 out of 35 patients (94%) who had the open procedure. Of the 42 patients treated laparoscopically, 26 (62%) were pain-free and 12 (29%) had a significant reduction in flank pain postoperatively. Of the 35 patients who had the open procedure, 21 (60%) were pain-free and 11 (31%) had a significant reduction in flank pain postoperatively. For more details, see the overview.