Management of prenatally detected fetal hydronephrosis.

The increased frequency of prenatal ultrasonography has resulted in an increase in the detection of fetal genitourinary abnormalities, many of which are of minimal clinical significance. Severe fetal urinary tract obstruction with associated oligohydramnios results in a recognizable constellation of physical findings, including renal dysplasia, pulmonary hypoplasia, and perinatal death. In selected cases, prenatal intervention to decompress urinary tract obstruction may reestablish amniotic fluid volume, prevent renal damage, and allow normal pulmonary development. After severe renal injury has occurred, intervention is unlikely to improve the prognosis of the affected fetus. Renal function may be analyzed prenatally by ultrasound examination and determination of chemical composition of fetal urine in order to identify fetuses in whom kidney development has not yet been irrevocably damaged and those likely to benefit from prenatal intervention. Postnatal renal evaluation with ultrasonography, voiding cystourethrography, and radionuclide imaging facilitates further characterization of the abnormality detected on prenatal ultrasound examination.