Assessment and Management of Fetal Hydronephrosis

Abstract

After completing this article, the reader should be able to: 1. Differentiate genitourinary abnormalities associated with hydronephrosis detected on fetal ultrasonography. 2. Describe the type of fetal hydronephrosis that requires a complete uroradiologic evaluation. 3. Characterize the complete postnatal uroradiologic evaluation of significant fetal hydronephrosis. 4. Delineate the factor that sets the timetable for postnatal uroradiologic evaluation. 5. Describe the neonates for whom diuretic renography is reserved. Ultrasonographic detection of antenatal anomalies in the fetus has increased steadily since its initial widespread use in the 1970s. During these early years, antenatal ultrasonography detected structural abnormalities in approximately 1% to 3% of all pregnancies. (1) Currently, it is estimated that genitourinary anomalies comprise 20% of all antenatally detected fetal anomalies. (2) In a recent British population-based study, fetal genitourinary anomalies were identified in 2.3% of women undergoing routine obstetric ultrasonography between 18 and 23 weeks of gestation. (3) Hydronephrosis clearly has become the most commonly detected antenatal anomaly on fetal ultrasonography. Detection of antenatal dilation of the urinary tract does not always indicate postnatal urinary tract obstruction or even a significant genitourinary anomaly. (4) Among infants diagnosed as having prenatal hydronephrosis or other genitourinary anomalies, the question often is raised about the need for and extent of the postnatal evaluation to assess the magnitude of this commonly detected antenatal anomaly. The purpose of this review is to provide a framework for assessment and management of antenatally detected hydronephrosis. Fetal hydronephrosis is a nonspecific finding that can be associated with multiple congenital anomalies of the genitourinary tract. A thorough understanding of disorders that can result in hydronephrosis postnatally allows the physician to assess the need for postnatal diagnostic tests and guide treatment recommendations. The congenital anomalies that may result in hydronephrosis can be categorized as disorders of urinary reflux and disorders of urinary obstruction. It can be …