In most instances, it occurs on only one side, with a normal kidney on the opposite side. In infants and children an abdominal mass that the mother or physician feels on examination, hematuria and urinary tract infection which prompts a radiographic examination, or gastrointestinal discomfort. A classic form of presentation in children is abdominal pain noted after fluids.
Urine output goes up and distends the kidney resulting in discomfort.
The dilated kidney is much more sensitive to mild trauma, and will bleed a bit. This usually alarms everyone and a radiographic exam is done which often will show a dilated kidney. The most common time for the diagnosis during pregnancy, as soon as the first sonogram is done, the topic may be brought up. Since the advent of evaluating the fetus and uterus during pregnancy the number of babies with this diagnosis is increasing. However, the degree of dilatation can vary from day to day, and its significance also varies significantly.