Pre- and postnatal ultrasonographic diagnosis of congenital obstructive uropathies.

Ultrasonography has proved particularly effective in evaluating the neonate with an abdominal mass, poor renal function, and an abnormal perinatal ultrasound scan. As a noninvasive, nonionizing, and relatively inexpensive examination, it can often make the preliminary diagnosis, streamline the work-up, and be used for follow-up studies.