- J. Bryan Carmody, MD*
- Rebecca B. Carmody, MD†
- *Department of Pediatrics, Division of Nephrology, The University of Virginia, Charlottesville, VA.
- †Department of Pediatrics, Division of Neonatology, The University of Virginia, Charlottesville, VA.
Drs Carmody and Carmody have disclosed no financial relationships relevant to this article. This commentary does contain a discussion of an unapproved/investigative use of a commercial product/device.
During a prenatal visit, a mother states that ultrasonography shows “something wrong with the baby's kidney.” On checking with the obstetrician, it is learned that the female infant has hydronephrosis of the left kidney on screening ultrasonography done at 20 weeks of gestation, with the renal pelvis having an anteroposterior diameter (APD) of 10 mm; there is a normal volume of amniotic fluid. What is the significance of this finding, and what should the mother and pediatrician anticipate doing when the infant is born?
Abnormalities of the kidneys and genitourinary tract are the most common abnormalities identified on routine screening prenatal ultrasonography, and among these, hydronephrosis—dilation of the proximal urinary collecting system with fluid—is the single most common abnormality identified, (1) occurring in approximately 0.6% of all scans. (2) With the increased use of high-resolution screening ultrasonography, pediatricians are confronted more and more frequently with the issue of how to interpret abnormal findings and manage these infants postnatally.
In approximately 35% of all cases of prenatal hydronephrosis, a pathologic condition can be identified postnatally, such as ureteropelvic junction (UPJ) obstruction, vesicoureteral reflux (VUR), posterior urethral valves (PUV), megaureter, or ureterocele. However, in approximately 50% of cases, the prenatal hydronephrosis is transient and not identified on postnatal evaluation; in an additional 15% of cases, hydronephrosis persists but is not associated with urinary tract obstruction (so-called …