Urinary System, Imaging and pathology Flashcards
Urinary system function
Eliminates waste from the body, regulates blood volume and blood pressure, control levels of electrolytes and metabolites, and regulate blood pH.
Blood supply and drainage of the urinary system
The superior and inferior vesicle arteries provide the blood supply to the bladder. These are indirect branches of the internal iliac arteries. The bladder also receives some of its blood supply from the obturator artery and the inferior gluteal artery
Renal arteries
Renal veins
venous drainage is by the vesical venous plexus (vesical veins) and innervation is provided by the vesical plexus, and inferior hypogastric plexus
What are nephrons?
Each of your kidneys is made up of about a million filtering units called nephrons. Each nephron includes a filter, called the glomerulus, and a tubule. The nephrons work through a two-step process: the glomerulus filters your blood, and the tubule returns needed substances to your blood and removes wastes.
In what ways do we image the urinary system?
Plain film KUB
US
IVU (Cystography)
CT Urography
MR Urography
Isotope renogram
Intervention
(Transplants)
Examples of problems we may see with the urinary tract system
urinary tract infection
calculus disease
vascular abnormality
trauma
parenchymal disease (any disease, disorder, or condition that causes damage to a person’s renal parenchyma. Patients who show continued damage to the renal parenchyma over a few months are subsequently diagnosed with chronic kidney disease.)
Cystoscopy& Ureteroscopy, what is it?
-Theatre procedure performed by Urologist
-Camera is passed into eh bladder via the urethra
-Can look at the inner lining of the bladder and ureters
-Catheters and other tools can be used to remove stones etc
KUB plain film will detect and miss what?
KUB will detect:
calcium stones
struvite
cystine stones
KUB will miss:
uric acid stones
small stones
stones obscured by bones or gas
For initial episodes of suspected urolithiasis, the KUB’s sensitivity for detecting stones is low (58%- 62%) (ACR)
Ultrasound of kidneys advantages and disadvantages
Advantage
Accessible
Good for diagnosing Hydronephrosis and renal stones
Requires no ionizing radiation
Safe, non-invasive…
ideal for pregnant patients & children
Sensitive for detecting urinary tract dilation
Disadvantages Poor visualization of ureteral stones
1. Urinary tract dilation can take hours to develop, so the diagnosis of obstructive may be missed at the initial evaluation.
2. May miss small stones and stones in ureters
3. Patients need to be hydrated before exam
4. Stone size cannot be accurately measured
Ultrasound
97% specificity
19% sensitivity
What does IVU or IVP mean
intravenous urogram (IVU)
intravenous pyelogram (IVP)
IVU (IVP) advantages and disadvantages
Advantages
Allow assessment of renal function
Shows location and degree of obstruction
Assess size of stone (sometimes)
Accessible
Provides information on anatomy and functioning of both kidneys
Disadvantages
Requires contrast
Can take a while to complete
Fail to identify alternate diagnoses
Variable image quality
? need Bowel prep and contrast media
Poor visualisation of genitourinary conditions
Delayed imaging required in high grade obstruction
Sensitivity 64 – 87%
specificity 92 – 94%
Limitations of US for urinary system
superimposed bowel
visualisation of renal pelvis and ureter
regional and distant metastases
observer dependency
US advantages in comparison to IVU
Advantages
safe / quick
staging - local/regional
bedside
no risk of contrast induced nephropathy
dynamic
Disadvantages
radiation dose (4.36mSv)
difficult to distend upper tracts
contrast induced nephropathy
re-evaluable hard copy
Non-contrast Helical CT for urinary imaging advantages
Preferred study for work-up of suspected urinary tract calculi.
Fast
No contrast
Characterize size & location of stone (and guide management ?)
Characterize degree of urinary tract obstruction
Higher sensitivity (96%) and specificity (98%) for ureterolithiasis than any other study (ACR)
Evaluate for other sources of pain.
Cost of CT is comparable to IVP (Pfister)
Virtually all stones are radiopaque
What can non-contrast helical CT show
Sometimes the ureteral mucosa is damaged
by the adjacent stone and becomes inflamed,
edematous, and thickened.
This can be seen on CT as a soft tissue, rim surrounding the stone
if a stone can’t be seen directly, then secondary signs of urolithiasis can help make the diagnosis…
Perinephric fat stranding (secondary to edema)
Hydronephrosis (dilation of kidney)
Hydroureter: (dilation of ureters)
What are phleboliths?
Calcified remnants of thrombi in veins.
Easily mistaken for urinary calculi on CT…
Calcifications are consistent with ureteral stone (red arrowhead)
and phleboliths (yellow arrowheads). (Urologystone.com)
