The size of the renal pelvis on ultrasonography in children.

Eighty-seven patients and 60 normal children were studied to determine the upper limit of the renal pelvic size in children and its relation to disease and age. The renal pelves were all measured by ultrasonography. Further radiologic examinations were performed on the disease group to confirm the final diagnosis. We found that a 10 mm diameter was the upper limit of the normal renal pelvis. Second, measuring the renal pelvic size on an ultrasonogram was highly reliable in diagnosing obstructive uropathy (100% sensitivity, 90.3% specificity). However, when the ultrasonogram with the 10 mm criterion was the sole diagnostic measure, many nonobstructive hydronephroses cases (26/37) were misdiagnosed. Therefore, other diagnostic tools should be employed. Third, the size of the renal pelvis was not influenced by age in children.