Purpose: To evaluate the factors affecting the effectiveness, safety, and success of retrograde holmium:yttrium–aluminum–garnet laser endopyelotomy as the primary treatment of ureteropelvic junction obstruction in adults. Methods: Adult patients who underwent retrograde holmium:yttrium–aluminum–garnet laser endopyelotomy as the primary treatment of ureteropelvic junction obstruction between January 2012 and June 2016 at our clinic were retrospectively analyzed. Success was defined as the relief of symptoms and the resolution of obstruction, as assessed via radiography. Factors affecting success were analyzed, such as the clinical characteristics, procedural outcomes, complications, and the type of ureteroscopy used in the procedure. Results: Procedural success was achieved in 29 (74.4%) out of 39 patients, with a mean age of 38.3 ± 12.3 years during a median follow-up duration of 44 (33–65) months. Failure occurred at a median of 4.5 (3–22) months. It was detected that the presence of primary obstruction, ipsilateral kidney function being >30% of normal, and the length of obstruction being <1 cm positively affected procedural success ( p = 0.009, p = 0.011, and p = 0.019, respectively). In the postoperative period, two Grade I and four Grade II complications were observed according to the Clavien–Dindo classification. There was a difference only in the operation time between semirigid (24) and flexible ureteroscopes (15), with the operation time being shorter with the use of a semirigid ureteroscope than with the use of a flexible uteroscope ( p < 0.001). Conclusion: Retrograde holmium:yttrium–aluminum–garnet laser endopyelotomy is a minimally invasive method that can be used effectively and safely as the primary treatment of patients with ureteropelvic obstruction, when long-term results are also taken into consideration. The decision of performing laser endopyelotomy should be made after a detailed evaluation of the characteristics of the patient as well as of the obstruction.
