Imaging - GU

Question 1

KUB

Answer 1

• Kidneys-ureters-bladder x-ray
• AP supine abdominal film
• Kidneys, ureters, bladder not typically visualized (despite name!)
• Can detect calcified kidney stones (80% are calcified): size, location
• Also can dx. constipation, SBO, free air (need upright as well)

Question 2

Intravenous Pyelogram (IVP)

Answer 2

• Injection of IV contrast dye, followed by abdominal x-rays at specific intervals
• Visualizes kidneys, ureters, bladder
• Look for obstruction produced by stones
• Also looks for kidney abnormalities (horseshoe, polycystic, tumors), bladder mass
• Risks: worsening renal failure in those with renal insufficiency; avoid if contrast allergy
• Largely replaced by CT now

Question 3

CT

Answer 3

• With or without IV contrast
• Renal stone protocol requires no contrast
• Visualizes kidneys, ureters and bladder (greater detail than IVP)
• Used to dx stones, renal tumors, renal congenital abnormalities
• Has largely replaced IVP
• Risk: radiation (avoid in pregnancy)
• Usually for first time kidney stone….after that not indicated

Question 4

Renal Ultrasound

Answer 4

• High frequency sound waves
• No radiation: consider in kids, pregnancy
• Assesses size, shape of kidneys/bladder
• Assesses for obstruction, renal abnormalities (mass, polycystic, horseshoe), bladder abnormalities
• Hydronephrosis indicates obstruction (usually due to a stone)

Question 5

Testicular Ultrasound

Answer 5

-Evaluate testicles, scrotum, epididymis

Conditions

• Testicular mass/cancer
• Torsion: diminished testicular blood flow
• Epididymitis
• Hydrocele, spermatocele

Question 6

Prostate Ultrasound

Answer 6

• Transrectal approach
• Look for hypertrophy, nodule, mass

Indications

• Nodule felt on exam
• Elevated PSA
• Urinary difficulty
• Assist with needle biopsy

Question 7

Retrograde Urethrogram

Answer 7

• Assesses for integrity of urethra, typically in setting of pelvic trauma
• Also assesses for stricture
• Dye injected into urethra, x-ray taken
• Contrast leakage suggests urethral disruption

Question 8

Cystogram

Answer 8

• Foley catheter placed, contrast instilled
• X-ray images bladder
• Evaluates for bladder mass, vesiculoureteral reflux, traumatic bladder rupture
• Much less radiation than CT
• “Radionuclide cystography” instills radionuclide to assess for reflux

Question 9

Voiding Cystourethrogram(VCUG)

Answer 9

• Used to evaluate for vesiculoureteral reflux, bladder rupture, urethral abnormalities
• Catheterize bladder, contrast injection followed by fluoroscopy (real-time x-ray images)
• Voiding increases intraluminal bladder pressure, may bring out reflux

Question 10

Retrograde Pyelogram

Answer 10

• Contrast injected into the ureter (via cystoscopy) to visualize ureter/kidney
• Used when IV contrast cannot be given for IVP or CT due to contrast allergy or renal disease
• Identifies filling defects from stones/tumors, delineates renal anatomy

Question 11

Cystoscopy

Answer 11

• Endoscopy of the bladder via the urethra
• Sterile water instilled through scope to distend bladder
• Evaluate bladder lesions
• May take biopsy through scope
• May go higher via urethroscope, e.g. to retrieve a stone

Question 12

Radioisotope Renography

Answer 12

• A nuclear medicine scan
• Radioisotope injected IV, concentrates in kidneys and is excreted into ureters
• Scan evaluates renal blood flow, function of kidneys, and assesses for obstruction
• Uses: evaluate renal failure, often used before kidney transplant to assess vascularity of kidney to be transplanted

Question 13

Captopril Radioisotope Renography

Answer 13

• Used to screen for renal artery stenosis (renovascular hypertension)
• Captopril (ACE inhibitor) given, produces vasodilation of efferent arterioles of glomeruli, decrease in perfusion pressure
• This causes decrease in GFR in renal artery stenosis, and decrease in radioisotope accumulation
• Captopril does not affect GFR in pts with normal renal arteries

Question 14

Renal Angiogram

Answer 14

• Selective catheterization of renal arteries, injection of contrast, x-ray imaging
• Visualizes main renal arteries and their branches
• Evaluates for renal artery stenosis, vascular tumors, aneurysms
• Stenosis may undergo angioplasty/stenting

Question 15

Urodynamic Testing

Answer 15

Assessment of bladder and urethral function

• Does the bladder hold urine properly?
• Does it empty properly and completely?

Indications

• Urinary incontinence
• Urgency/frequency
• Problems initiating stream
• Frequent UTI’s

Uroflometry

• Measures bladder pressures and rate of bladder emptying
• Checks for bladder muscle weakness, outflow obstruction

Post-void residual measurement

• Residual urine in bladder after voiding (>100cc is high)
• Measure by bladder ultrasound or catheter drainage
• If high: outflow obstruction or bladder detrusor muscle dysfunction;
• High post-void residual associated with “overflow incontinence”

Cystometry

• Measures pressure in bladder, how full it needs to be before urge to urinate; can identify involuntary bladder contractions
• May have rectal pressure catheter as well

Urethral pressure profilometry
-Measures strength of urethral sphincter contraction