Overview of Antenatal Hydronephrosis
Antenatal (i.e., before birth) hydronephrosis is a condition in which the outflow of urine from the kidney is obstructed, resulting in fluid-filled enlargement. The condition is usually detected by ultrasound, as early as the first trimester of pregnancy.
Antenatal hydronephrosis can be mild, moderate, or severe and it requires monitoring before birth and during infancy and childhood. Occasionally, the kidney appears enlarged (dilated) during antenatal ultrasound yet functions normally after birth.