[Postnatal evaluation and management of fetal pyelectasis on prenatal ultrasound]

Fetal pyelectasis is the most frequently encountered anomaly on prenatal ultrasound. The ultrasound diagnostic criteria are well established: nature of dilated structures, degree of dilatation, ultrasound appearance of the kidneys, volume of amniotic fluid. Ultrasound can also determine if the anomaly is isolated or not, which is important for the management and prognosis of the pregnancy. Ultrasound is the initial postnatal study to evaluate the urinary tract. Further management will be based on suspected diagnosis. In cases of suspected vesico-ureteral reflux, VCUG is performed. In cases of obstructive uropathy or complex malformation (duplications), MRI is performed at 6 months of age to further define the anatomy of the urinary tract. Radionuclide renogram, performed in most cases, allows evaluation of split renal function. Follow-up ultrasound is important to monitor renal development, urinary tract dilatation and appearance of the renal parenchyma. Functional follow-up is assured by radionucline renography. This comprehensive follow-up is recommended to prevent complications and progressive loss of renal function.