Because voiding cystourethrography(VCUG) is an invasive method, we studied whether VCUG could be postponed through evaluation of alternative non-invasive tests including renal ultrasonography and ^99mTc-DMSA renal scan.

We reviewed the medical records of 175 patients initially diagnosed with febrile urinary tract infection during the one year period of 1999, and compared 3-tests : renal ultrasongraphy, ^99mTc-DMSA renal scan, and VCUG.

Renal ultrasonography didn't contribute to the prognostication of pyelonephritis(photopenic areas) or vesicoureteral reflux(VUR). Presentation of photopenic areas in ^99mTc-DMSA renal scan was related to VUR. If both findings of renal ultrasonography and ^99mTc-DMSA renal scans were normal, this condition was closely related to normal results in VCUG. And if both examinations were abnormal, the condition was closely related to VUR. But this state could not always guarantee the normal result from VCUG because of low sensitivity in finding VUR.

In cases in which acute phyelonephritis is demonstrated by ^99mTc-DMSA renal scan, VCUG is required. In addition to this, if the conditions of hydronephrosis, vesicoureteral dilatation, increases of renal volume, and changes of echogenesity are shown by renal ultrasonography, VCUG should be performed. If a patient has difficulty undergoing VCUG, temporary postponement of VCUG can be taken into consideration, but only in cases where both examinations of renal ultrasonography and ^99mTc-DMSA renal scan are normal. Nevertheless, close observation is be advised even in this case.