The postnatal treatment of asymptomatic unilateral hydronephrosis due to ureteropelvic junction obstruction remains controversial, and the timing of and indications for surgical intervention are continuously debated. There is no consensus on the best follow-up during expectant management. The various modalities and parameters have been discussed along with their pros and cons and an attempt has been made to clear up the controversies.
Keywords: Diuretic renography; Plasma renin activity; Pyeloplasty; Renal scintigraphy; Resistive index; Society for Fetal Urology grading; Ultrasonography; Unilateral hydronephrosis; Ureteropelvic junction obstruction; Urinary biomarkers.