Background: There is not a well established method for further screening of asymptomatic microhematuria found through annual health examinations. However, it is apparent that a large number of examiners are using ultrasonography for screening. When slight hydronephrosis is found through screening, it is difficult to determine whether further examinations, such as intravenous pyelography (IVP), should be performed. In this paper, we discuss the usefulness 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 ultrasound laboratory of Toma Hospital was carried out on a total of 1906 patients with asymptomatic microhematuria, which was found by routine annual health examination, from January 1996 to December 1998. Slight hydronephrosis was 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 (38.6%) of 57 patients. Of 35 cases in which slight hydronephrosis persisted after urination, there were no abnormalities on IVP in 32 patients, while abnormalities were found in three patients. Two of these had ureteropelvic junction stenosis and the remaining one had a ureteral stone.
Conclusion: The results of this study indicate that post-voiding repeated renal ultrasonography is useful for avoiding unnecessary further examination to determine whether upper urinary tract obstruction exists, when slight hydronephrosis is observed upon screening by simultaneous renal and urinary bladder ultrasonography for asymptomatic microhematuria.