This document discusses and provides images of various causes of ureter obstruction, including kidney stones, congenital abnormalities, post-surgery strictures, radiation cystitis, pelvic tumors, bladder cancer, interstitial cystitis, ureteroceles, retrocaval ureters, transitional cell carcinoma, hydronephrosis of pregnancy, retroperitoneal fibrosis, and obstructing valves at the ureteropelvic junction. The images demonstrate dilated ureters and kidneys caused by proximal obstructions from these various etiologies.

1. 19Obstruction of the Ureter

2. CLINICAL IMAGAGING
AN ATLAS OF DIFFERENTIAL DAIGNOSIS
EISENBERG
DR. Muhammad Bin Zulfiqar
PGR-FCPS III SIMS/SHL

3. • Fig GU 19-1 Obstructing ureteral calculus.
Excretory urogram demonstrates a prolonged
nephrogram and marked dilatation of the
collecting system and pelvis proximal to the
obstructing stone (arrow).

4. • Fig GU 19-2 Congenital ureteropelvic junction
(UPJ) obstruction. Note the characteristic kink
or angulation at the UPJ (arrow).

5. Fig GU 19-3 Postsurgery stricture. Fibrotic narrowing of the
proximal ureter secondary to stone removal.

6. • Fig GU 19-4 Radiation cystitis causing ureteral obstruction. After
external and intracavitary radiotherapy for cervical cancer, an
excretory urogram shows the bladder wall to be thickened and
bladder opacity to be reduced. Narrowing of the distal ureters
causes bilateral hydronephrosis.4

7. Fig GU 19-5 Pelvic tumor. Dilatation of the right ureter and pelvis
due to partial obstruction by a large ovarian mass.

8. • Fig GU 19-6 Bladder cancer causing left ureteral
obstruction. Contrast material opacifies the distal left
ureter to the point of obstruction. The tumor involves
the ureteral orifice and produces a
“pseudoureterocele” appearance.4

9. • Fig GU 19-7 Severe interstitial cystitis. Bilateral ureteral
obstruction and marked contraction of the bladder
secondary to severe interstitial cystitis due to systemic
lupus erythematosus in a young woman on steroids. The
bladder capacity was reduced to approximately 1 ounce.4

10. • Fig GU 19-8 Simple ureterocele (arrows).

11. • Fig GU 19-9 Ectopic ureterocele. (A) Excretory
urogram demonstrates a large lucency (arrows)
filling much of the bladder. There is slight
downward and lateral displacement of the
visualized collecting system on the left. (B)
Cystogram shows contrast material refluxing to
fill the markedly dilated collecting system
draining the upper pole of the left kidney. Note
the severe dilatation and tortuosity of the ureter.

12. Fig GU 19-10 Retrocaval ureter. Note the medial swing of the
right ureter distal to the ureteropelvic junction.

13. • Fig GU 19-11 Transitional cell carcinoma of the
ureter. Irregular stricture (arrow) causing
proximal ureteral and pelvocalyceal dilatation.

14. • Fig GU 19-12 Hydronephrosis of pregnancy. Excretory urogram performed
3 days postpartum demonstrates bilateral large kidneys with dilatation of
the ureters and pelvocalyceal systems, especially on the right. The large
pelvic mass (arrows) indenting the superior surface of the bladder
represents the uterus, which is still causing extrinsic pressure on the
ureters.

15. • Fig GU 19-13 Retroperitoneal fibrosis. Marked bilateral hydronephrosis
with bilateral ureterectasis above the level of the sacral promontory.
Below this point, both ureters, where visualized, appear to be normal in
caliber. No definite ureteral deviation is seen. An excretory urogram
performed 1 year previously was entirely normal.7

16. • Fig GU 19-14 Obstructing valve (arrow) at the
ureteropelvic junction. Retrograde study shows smooth
infoldings below the valve representing fetal folds,
which usually regress as the child grows.19