Do current scientific reports of hydronephrosis make the grade?

Background: In December 2014, Nguyen et al. introduced the Upper Tract Dilation (UTD) classification scheme, hoping to unify multiple disciplines when describing ultrasound imaging of congenital hydronephrosis. We hypothesized that the academic community has been slow to adopt its use in publications.

Primary aim: To evaluate which hydronephrosis grading systems were currently preferred in publications.

Study design: A PubMed® search for hydronephrosis was performed, and abstracts between May 2017 and May 2019 were reviewed. The following data points were collected from the 197 manuscripts meeting inclusion criteria: journal, first and senior author specialty, country, type of article, primary pathology, and classification of hydronephrosis when present. Differences between use of classification system, and author specialty, manuscript type, and pathology were evaluated.

Results: First and/or senior author specialties were most commonly pediatric urology, urology, pediatric surgery, and pediatric nephrology. The manuscripts were comprised of retrospective studies (48.2%), prospective studies (25.4%), case reports (15.7%), review articles (9.1%), and systematic reviews (1.5%). The most common pathologies were hydronephrosis (36.5%) and ureteropelvic junction obstruction (21.3%). Over 20% of manuscripts did not categorize hydronephrosis at all. The UTD classification was used by 5.6%, while Society for Fetal Urology (SFU) grading was used by 37.1% and Anterior-Posterior Diameter (APD) measurements by 32.5%. The Summary Table presents grading system by manuscript type, specialty, and pathology.

Discussion: There is great variability in hydronephrosis grading. One potential weakness of our study is that sufficient time may not have passed for the UTD system to be adopted. Researchers may need more time to complete and publish their studies, or could be awaiting further validation of UTD utility. They could also be hesitant to change systems when it is unknown if one classification schema is superior to another, either in general or for specific diagnoses. Another weakness is that this study does not quantify what, if any, systems are used clinically. Some attempt to provide objective classification would help clarify the implications of the manuscript for research or clinical applications. Reviewers should ensure that where possible, adequate descriptions of hydronephrosis are included. Education outreach to other specialties may help increase objective grading in research.

Conclusions: The UTD system is not commonly utilized in the literature. SFU grading is applied most commonly, followed by APD measurements. Over one third of manuscripts used no classification system or descriptive terminology.