Ureteropelvic junction obstruction: What we know and what we don't know

Purpose: Ureteropelvic junction (UPJ) obstruction is by far the most common cause of pediatric hydronephrosis. The widespread use of antenatal ultrasonography and modern imaging techniques has resulted in earlier and more common diagnosis of hydronephrosis. However, compared with this increased earlier detection, little has changed regarding the management of hydronephrosis. Through this review, we wish to provide an overview of the studies done to date and search for areas that warrant further study. Materials and Methods: Through PubMed, we reviewed the literature on the subject of UPJ obstruction in the pediatric population. We also present data from our institution regarding recent trends in the evaluation and treatment of UPJ obstructions. Results: In addition to conventional imaging studies, attempts are being made at making use of biochemical parameters (e.g., β2 m, N-acetyl-β-D-glucosaminidase [NAG], transforming growth factor [TGF]-β, etc.) as not only indicators of intervention but also prognostic factors during follow-up. Although we routinely use radionuclide imaging to evaluate renal function, a more accurate novel tool that can represent true renal function is needed. With the development in the field of laparoscopic and minimally invasive surgery, the role of laparoscopy and robot-assisted laparoscopic pyeloplasty is expanding, even in the pediatric population. However, relatively little is known about the factors that might be associated with postoperative outcomes. Conclusions: Not missing the optimal time for surgical intervention is as important as avoiding unnecessary surgery. Continuous development and refining of surgical skills for UPJ obstruction repair are requisites for (pediatric) urologists as is in-depth basic research of the disease.