What postnatal imaging studies should we use to evaluate prenatal pyelectasis?
Ultrasound is the initial postnatal study to evaluate the urinary tract. Besides measuring the antero-posterior diameter of the neonatal renal pelvis (ADRP) to assess interval change from prenatal studies, we also search for other sonographic abnormalities. These include: calyceal or ureteral dilatation; pelvic and/or ureteral wall thickening; renal parenchymal echogenicity, including corticomedullary junction differentiation; renal cysts; cortical scarring; small sized kidney and other signs of renal dysplasia. Immediate ultrasound evaluation should be performed if there is a known prenatal diagnosis of moderate or severe renal pelvis dilatation, ADRP =/>10mm, since these children have a high incidence of obstructive uropathies that may require surgical intervention. If the pyelectasis is confirmed or has progressed from the prenatal study, the ultrasound study will be followed by voiding cystourethrogram (VCUG) and radionuclide Lasix renogram. Early diagnosis of urinary tract obstruc
