Background Intravenous urography (IVU) combined with add-on CT (IVU-CT) can help to provide more diagnostic information for determining the localization and nature of ureteral abnormalities with less irradiation dose.This study aimed to determine the value of IVU-CT for diagnosis of ureteral diseases,where IVU is insufficient to determine the diagnosis.Methods Two hundred and eighty patients underwent IVU for suspected ureteral disorders,which identified a definite diagnosis in 184 cases and was insufficient for definite diagnosis in 96 cases designated as indeterminate diagnosis.Subsequently 90 patients (six patients declined CT) with indeterminate diagnosis consented to undergo immediate or delayed helical CT scan.The CT data were transferred to the workstation for post-processing,and the cost and mean effective dose for each imaging method were calculated and compared indirectly.Results Of the 90 indeterminate diagnosis cases,diagnosis was determined in 86 cases by IVU-CT with a diagnostic accordance rate of 95.6％,while 184/280 (65.7％) had diagnosis determined by IVU alone.There was a significant difference between IVU and IVU-CT in the determination of the diagnosis of ureteral diseases (x2=36.4,P <0.05).The cost of IVU equals to 1/8-1/9 of that for CT urography (CTU),and the cost of IVU-CT is as much as 1/3 of CTU.CTU results in the highest mean effective dose,approximately nine times that for IVU and three times that for IVU-CT.Conclusion IVU-CT provides valuable information for the localization and diagnosis of ureteral abnormalities and may be considered as an efficient,cost-effective and low-dose diagnostic technique in this setting.