Congenital Hydronephrosis in the Newborn is a commonly detected renal abnormality found on in utero imaging in up to 5% of pregnancies. The most common etiology for isolated hydronephrosis, i.e. not associated with other urinary tract abnormalities, is transient or physiologic (50-70%) and likely to resolve within the first 2 years of life. The degree of dilation, however, may indicate the presence of genitourinary pathology such as ureteropelvic junction obstruction, vesicoureteral reflux, ureterocele, ectopic ureter, or posterior urethral valve.
