Assessment of Fetal Hydronephrosis Using the Urinary Tract Dilation Classification System: Implications for Postnatal Treatment and Parental Counseling

IntroductIonAntenatal urinary tract dilation (UTD) in the fetus presents a diagnostic quandary with prognosis ambiguity because it is related to numerous etiologies, uropathies, and as a component of an uncountable wide range of syndromes.The prevalence of UTD ranges from 1 to 2%. 1 The majority of UTD in fetuses are physiologic or transient and resolve on their own. 2 The fundamental goal of UTD detection is to distinguish between the physiological and pathological types of UTD so that in utero and postnatal treatment and advice may be provided.Ranked from highest to lowest prevalence, the causative factors of UTD include transient dilation of the collecting system (41-88%), upper/lower urinary tract obstructive uropathy, including conditions like ureteropelvic junction obstruction (10-30%), ureterocele/ectopic ureter (5-7%), ureterovesical junction obstruction (5%), posterior urethral valve (PUV), and urethral atresia (1-2%).Additionally, nonobstructive processes like vesicoureteric reflux (VUR) (10-20%), multicystic dysplastic kidney (4-6%), and megaureters (5%) 1,