Post-voiding repeated renal ultrasonography for slight hydronephrosis detected during screening for asymptomatic microhematuria

Background: There is not a well established method for further screening of asymptomatic microhematuria found through annual health examinations. Howe ver, it is apparent that a large number of examiners are using ultrasonogra phy for screening. When slight hydronephrosis is found through screening, i t is difficult to determine whether further examinations, such as intraveno us pyelography (IVP), should be performed. In this paper, we discuss the us efulness of post-voiding repeated renal ultrasonography, which was applied to 57 patients with slight hydronephrosis found in a screening. Methods: Ultrasonography in the kidney and the urinary bladder at the ultra sound laboratory of Toma Hospital was carried out on a total of 1906 patien ts with asymptomatic microhematuria, which was found by routine annual heal th examination, from January 1996 to December 1998. Slight hydronephrosis w as found in 57 (14 males and 43 females) of 1906 patients and post-voiding repeated renal ultrasonography was carried out on all patients. Results: Slight hydronephrosis had disappeared and IVP was avoided in 22 (3 8.6%) of 57 patients. Of 35 cases in which slight hydronephrosis persisted after urination, there were no abnormalities on IVP in 32 patients, while a bnormalities were found in three patients. Two of these had ureteropelvic j unction stenosis and the remaining one had a ureteral stone. Conclusion: The results of this study indicate that post-voiding repeated r enal ultrasonography is useful for avoiding unnecessary further examination to determine whether upper urinary tract obstruction exists, when slight h ydronephrosis is observed upon screening by simultaneous renal and urinary bladder ultrasonography for asymptomatic microhematuria.