Urinary Tract Incontinence Imaging

Imaging of urinary incontinence involves the depiction of the different parts of the urinary tract. Formerly, excretory urography was to assess the kidneys and ureters and as a semiquantitative measure for assessing kidney function. Owing to the increasing availability of ultrasonography and detailed information about the architecture of the kidneys and the ureteral orifice, ultrasonography has become widely used for evaluating causes of incontinence. Breeding examinations for the assessment of the ureters use ultrasonography as a basic tool. Administration of a diuretic is very helpful in enhancing the visibility of the ureteral jets during ultrasonographic evaluation.

Renal ultrasonography can also be used as a screening tool for congenital renal diseases such as aplasia, hypoplasia, or dysplasia and polycystic kidney disease.

Moreover, the ureterovesicular junction can be visualized using ultrasonography. In normal dogs, it appears as a small convex structure at the dorsal part of the bladder. Identifying a ureteral jet in the region of the trigone confirms a normal ureterovesicular junction. In ectopic ureters, the course of the dilated ureters appears to be past the bladder neck. Secondary dilation of the renal pelvis and inflammatory changes may be present.

In questionable cases or if intrapelvic changes are suspected, computed tomography (CT) is used. CT has an advantage, in that it enables imaging of the entire urinary tract without superimposition. A low dose of contrast medium (400 mg I/kg body weight) results in good image quality. Multiplanar and 3D reconstructions are used to add information for example for surgical planning. By using excretory CT, it is possible to calculate glomerular filtration rate using a two-compartment model. A drawback of CT is the need for general anesthesia. Optimal depiction of the ureters occurs approximately 3 min after contrast administration and lasts for 1 h. For better visualization of the trigone, the urinary bladder is filled with negative contrast before the study.  [...]