Introduction. The standard approach to the treatment of short ureteropelvic junction (UPJ) obstruction is the Anderson-Hynes procedure. Despite its high efficiency and low complication rate, there are ongoing studies which study the modification of the procedure using open, laparoscopic, and robotic approaches.
Aim. To describe a modified pyeloplasty technique with an assessment of the anatomical and functional results in comparison with the Anderson-Hynes procedure.
Materials and methods. The results of 1,768 procedures for short UPJ obstruction and hydronephrosis performed using open (804), laparoscopic (888), and robotic (76) approaches in children and adults from 2000 to 2023 are presented in the article. A technique for horizontal ureteropyeloanastomosis after UPJ resection was developed by V.V. Sizonov and M.I. Kogan. A comparative analysis of the anatomical and functional results of vertical (standard) and horizontal anastomoses of the ureteral pelvis was performed using mathematical methods of the theory of hydrodynamics, and imaging studies after 12 months of follow-up.
Results. Horizontal anastomosis of the renal pelvis and ureter increases the passage of urine by 19.75% compared to vertical anastomosis. Horizontal anastomosis is less tense after resection of the ureteral pelvis. Postoperative dynamics of the anteroposterior size of the renal pelvis after horizontal anastomosis reliably demonstrates accelerated reduction compared to standard technique. Horizontal anastomosis is associated with a significantly higher increase in GFR compared to vertical anastomosis.
Conclusion. The author's technique of horizontal anastomosis between the ureter and pelvis has reliable anatomical and functional advantages over the Anderson-Hynes technique when performing open, laparoscopic and robotic pyeloplasty.

Keywords: modifications of Anderson-Hynes pyeloplasty, Anderson-Hynes pyeloplasty, ureteropelvic junction obstruction, hydronephrosis, efficacy, safety