Page 463 - Feline diagnostic imaging

27.4 ­ladder 475
Unilateral hydronephrosis and hydroureter was found in trigone. Positive contrast urethrography may be useful in
an 8‐month‐old Maine Coon cat during ultrasonography to males. An abnormal opening can sometimes be visualized
evaluate the abdomen prior to surgery for a retained testicle on vaginoscopy in females [36]. Ultrasonography can be
[7]. An excretory urogram was performed using iopamidol, useful in identifying hydronephrosis and/or hydroureter,
revealing strictures in the proximal and middle areas of the thus identifying the affected side in questionable cases
left ureter. No intervention was done because the cat was where obstruction is present.
asymptomatic at the time. Ureteral stenosis occurs rarely
and was reported as a congenital lesion in a 3.5‐year‐old cat 27.3.3 Ureterocele
[34]. The cat initially was asymptomatic, with enlarged kid-
neys being noticed on a routine wellness examination. A ureterocele is a rare condition that occurs when the distal
Ultrasonography revealed that renomegaly was caused by portion of the ureter becomes dilated. On excretory urogra-
severe hydronephrosis, particularly of the left kidney. The phy, as contrast enters the ureters, the dilated portion of the
left kidney had minimal remaining cortex and medulla and ureter will be radiopaque compared to the urine in the blad-
dilation of the proximal ureter in addition of the pelvis. The der. Conversely, on positive contrast cystography, radio-
right kidney had better preservation of the cortex and the paque contrast fills the bladder while the dilated portion of
right ureter was not dilated. The cat was returned 10 months the ureter will be less radiopaque. Ultrasonography can also
later when clinical signs of renal failure developed. The be used to demonstrate the dilated distal ureter appearing
degree of hydronephrosis had worsened but neither ureter within the urinary bladder.
was dilated. No calculi were visible at either examination.
On necropsy, both ureters were found to have tortuous
proximal segments at the ureteropelvic junction. 27.4 Bladder

27.3.1 Ureteral Trauma 27.4.1 Ruptured Bladder
Causes of ureteral trauma include motor vehicle incidents, The main sign on survey radiography is a loss of serosal
blunt force trauma, and gunshot injuries. Excretory urogra- detail because of the presence of fluid within the abdomen.
phy and ultrasonography are both useful in determining the The urinary bladder may or may not be visible. A hazy
status of the kidneys and ureters but excretory urography is appearance to the retroperitoneal space suggests that the
more likely to identify the source of uroabdomen. In one ureter may be ruptured rather than the urinary bladder.
case, excretory urography revealed lack of a pyelogram and Rupture of the urinary bladder is best confirmed with
cystogram following intravenous administration of iohexol positive contrast cystography but excretory urography is a
[35]. On ultrasonography, renal perfusion was normal but better choice when an indistinct retroperitoneal space sug-
both renal pelves were dilated and fluid was seen in the ret- gests that urine within the peritoneal space is due to rup-
roperitoneal space. No abnormalities were seen on Doppler tured ureter rather than ruptured bladder. When rupture of
ultrasound. Surgery revealed a crush injury of the right ure- the bladder is present, infusion of iodinated contrast into
ter and complete rupture of the left ureter. There were also the urinary bladder will result in positive contrast being
small tears in the diaphragm and body wall. Ureteral stents visualized outside the bladder in the peritoneal space
were initially placed but resolution of clinical signs occurred (Figure 27.24).
when subcutaneous ureter bypass devices were implanted. Ultrasonography is generally not useful in determining
Nuclear scintigraphy can be helpful in determining the the source of uroabdomen because the hole will not be vis-
viability of the kidneys. In this case, the left and right ible although free fluid will be apparent. In some cases,
kidneys contributed 66% and 33% of the total glomerular mucosal herniation is present instead of complete
filtration rate (GFR), respectively. Consequently, it was felt rupture.
to be important to preserve both kidneys.
27.4.2 Bladder Calculi
27.3.2 Congenital Lesions of the Ureters
As with the kidney and ureter, calcium oxalate and stru-
Ectopic ureter is an uncommon condition in cats in which vite continue to be among the most common causes
the ureter fails to enter the bladder in its normal location, of feline urolithiasis although the incidence of struvite
possibly resulting in a degree of urinary incontinence [36]. calculi appears to be decreasing, probably due to changes
The abnormal location of the ureter can result in partial instituted by cat food manufacturers [29]. Ultrasonography
ureteral obstruction, leading to hydroureter and hydro- and radiography are both useful for evaluating for these
nephrosis in some cases. Excretory urography may calculi. Since the calculi can be found at variable locations,
demonstrate the abnormal course of the ureter past the care should be taken to check the entire urinary tract,