Purpose or Case Report: Introduction: The American Consensus established risk groups for urinary tract dilation (UTD), however it has not been validated. Purpose: To validate the usefulness of the upper UTD risk groups according to a long-term outcome of patients stratified with a homologous classification.
Methods & Materials: Homsy grading system is comparable to the Consensus: mild hydronephrosis (HN): anteroposterior pelvic diameter (APPD) ≤15 mm without calycial dilation and normal parenchyma -, moderate (M) – APPD > 15 mm with calycial dilation and normal parenchyma - and severe (S) – APPD > 15 mm, calycial dilation and parenchymal thinning- , equivalent to low (P1), intermediate (P2) and high (P3) risk groups respectively. Frequency of presentation, outcome for each risk group was analyzed in 919 patient with prenatal UTD. Possible predictors of evolution: gender, bilaterality, value of APPD, size and renal function, urinary tract infection (UTI) was determined. The outcome was assessed as resolution, stability or progression . Statistics: descriptive analysis: averages, percentages.
Results: Out of 919 newborns, 537 (58.4%) had mild HN-P1-, in 230 (42.8%) was bilateral, 88 NB (9.5%) had M HN – P2- and 43 (5%) had S HN- P3-. Median follow-up: 30 months (r: 12-212m). 80% of mild HN-P1- resolved spontaneously during the first year of life. Only 1% progressed and required surgery, less than 10% had a UTI. Bilaterality did not imply a worse prognosis either in terms of outcome or in UTI rate. In patients with M HN- P2- 2/3 resolved spontaneously the dilation , 73% with APPD 15 to 25mm in the first postnatal ultrasound in an mean time of 16 months;14% progressed (mean APPD >24 mm) and required surgery. Increased renal size and supranormal function were predictors for surgery.There were no statistically significant differences in the outcome by sex (p = 0.44), laterality and UTI. All the S HN-P3-were resolved surgically, except in 3 patients in whom the dilation regressed spontaneously.
Conclusions: Both classifications are based on the assessment of APPD and renal characteristics, and establish the same limit to define mild HN-P1-, being the most frequent abnormality found with an excellent prognosis. APPD was the most important predictor of clinical outcome. Our long-term follow-up results allow to validate the usefulness of the grading system proposed by the American consensus.