The utility of retrograde pyelography to follow up incompletely opacified ureters on CT urography.

Purpose: Retrograde pyelography (RPG) is used in some centers to further evaluate patients with incompletely opacified segments on CT urography (CTU). This study intends to evaluate the utility of this imaging combination in terms of the yield of abnormal findings on the follow up RPG.

Methods: In this retrospective study, we searched the radiology database over a three-year period (11/1/2015-10/30/2018) for patients who had a CTU and then a diagnostic RPG within 180 days. Images and reports were reviewed from this period for patients who met the inclusion criteria.

Results: 292 patients underwent a CTU with follow up RPG over the search period. 131/292 RPGs (44.9%) were performed because the CTU described at least one incompletely opacified ureteral segment. Of the 148 ureters evaluated in these 131 patients, 4 ureters (2.7%) showed an abnormality on follow up retrograde pyelogram-two revealed a stricture at the unfilled segment, and two revealed contour irregularity in the distal ureter (biopsy showed urothelial cell carcinoma in these two).

Conclusion: There is a relatively low yield for detecting ureteral abnormalities when a retrograde pyelogram is performed after a CTU to evaluate an incompletely opacified ureteral segment-2.7% in our study, with only two of these incompletely opacified segments containing urothelial cancer (1.4%). In these two cases, a ureteral abnormality was visible on the CTU and RPG would seem to have a very low yield for follow up of unopacified ureteral segments if the ureters are otherwise normal-appearing on CTU and there is no hydronephrosis.