Summary
Patients with urological symptoms are diagnosed based on clinical features and routine diagnostics. Urodynamic tests help to evaluate functional and anatomical abnormalities of the lower urinary tract. The most common tests are cystometry, uroflowmetry, urethral pressure profile, and leak point pressure. Imaging may be used in combination to diagnose underlying pathologies and is often used to assess for anatomical obstructions or abnormalities (e.g., urinary obstructions caused by kidney stones, renal masses).
Procedures in urology include those involving the kidneys (e.g., percutaneous nephrolithotomy), ureters (e.g., ureteral stenting), bladder (e.g., transurethral resection of bladder tumor), prostate (e.g., transurethral resection of the prostate), penis (e.g., circumcision), and scrotum (e.g., vasectomy), as well as infertility procedures (e.g., testicular sperm extraction).
For more on renal function tests, urinalysis, urine dipstick, and renal biopsy, see “Diagnostic evaluation of the kidney and urinary tract”.
For information on “Urine culture”, see the article “Urinary tract infections.”
Urodynamic studies
Urodynamic studies use the characteristics of urinary flow (pressure and flow rate at various points during micturition and at rest) to evaluate the functional and anatomical abnormalities of the lower urinary tract.
Cystometry
- Description
-
Indications
- To differentiate between detrusor overactivity and stress incontinence
- To determine neurological abnormalities of the bladder (e.g., hypotonic bladder)
-
Procedure
- Bladder is filled with water through a urethral catheter at a steady rate
- The vesical pressure is measured through this urethral catheter, while the intraabdominal pressure is measured via a vaginal or rectal pressure catheter
- The detrusor pressure is the difference in pressure between these two catheters
Uroflowmetry
- Description: an objective, noninvasive test used in the evaluation of patients with suspected bladder outlet obstruction
-
Indications
- Outlet obstruction (e.g., benign prostatic hypertrophy, urethral overactivity, urethral stricture following surgery)
- Weak detrusor (e.g., hypotonic bladder)
- Increased valsalva during voiding
-
Procedure
- Patient is asked to void into a funnel that measures the volume and rate of urine flow.
- Measures the volume of urine voided over time
-
Interpretation
- Normal: a continuous, single bell-shaped curve with urine volume > 200 mL (over 15–30 seconds) and at a rate > 15 mL/sec
- Abnormal: an abnormal curve or urine volume at a rate < 15 mL/sec
- Bell-shaped with a flattened curve: indicates obstruction (most likely due to benign prostatic hypertrophy)
- Rapid rise followed by a plateau: indicates obstruction (most likely due to urethral stricture)
- Irregular, undulating, wavy: indicates bladder sphincter dyssynergia
Pressure-flow study [1]
-
Description
- To determine the underlying mechanism of an abnormal uroflowmetry assessment
- Measures detrusor pressure while voiding
-
Indications
- Increased valsalva during voiding
- Weak detrusor (e.g., hypotonic bladder)
- Outlet obstruction (e.g., benign prostatic hypertrophy, urethral overactivity, urethral stricture following surgery)
Urethral pressure profile
-
Description
- Assesses intrinsic sphincter function
- Measures the intraluminal urethral integrity at different pressures (filling and voiding pressures are measured under different types of provocation, e.g., Valsalva maneuver, coughing, etc.)
-
Indications
- Sphincter dysfunction (e.g., due to multiparity, low estrogen levels)
- Urinary stress incontinence
- Procedure: A specialized urethral catheter, mounted with microtransducers, is withdrawn at a slow and steady rate from the bladder until it exits the external urethral meatus.
Leak point pressure
-
Description
- Assesses intrinsic sphincter function (but during dynamic testing, unlike urethral pressure profile testing)
- Determines the intravesical pressure required to produce urine leakage in the presence of increased abdominal pressure (i.e., during valsalva maneuver) and the absence of detrusor contraction
- May be performed during cystometry
-
Indications
- Sphincter dysfunction (e.g., due to multiparity, low estrogen levels)
- Urinary stress incontinence
Postvoid residual volume
- Description: measures the volume of urine that remains in the bladder after voiding
- Indications
- Procedure: : may be performed using straight catheterization or ultrasound of the bladder
- Interpretation: A postvoid residual volume < 50 ml is normal.
EMG
- Description: a procedure that studies the electrical potentials of depolarized muscle, specifically the neural pathways involved in micturition (by evaluating the segment of the sacral spinal cord involved)
- Indication: to determine neurological abnormalities of the bladder (e.g., hypotonic bladder)
- Procedure: Electrodes or a concentric needle are inserted into the urethral sphincter.
References:[2][3][4][4]
Imaging techniques
Ultrasound
-
Indications
- Renal: visualization of renal tumors, renal cysts, nephrolithiasis, hydronephrosis
- Bladder: bladder wall thickness, bladder calculi, tumors, urinary retention
- Prostate; : to estimate prostate volume, shape, echogenicity, and prostatic abscesses or masses
- Scrotal and penile: to evaluate for testicular torsion, cryptorchidism, trauma, testicular tumors, varicocele, and epididymitis.
The bladder should be full to visualize pelvic structures.
CT
-
Indications
- Investigation of choice to detect urinary calculi and renal masses
- Visualization of the urothelium in suspected malignancies and cases of obstruction
- CT angiography helps evaluate acute pelvic trauma and tumor blood supply, as well as diagnose renal vascular malformations
MRI
-
Indications
- To differentiate between renal cysts and neoplasms
- For accurate staging of bladder and prostate cancers
- As an alternative to contrast CT in patients who are allergic to iodine-based radiocontrast
Renal scintigraphy
- Description: a diagnostic procedure in which radioisotopes are used to assess the anatomy and function of the kidneys
-
Indications
- To detect bone metastases in prostate cancer, renal scarring (usually associated with reflux), significant urinary obstruction
- Estimation of differential renal function
- Screening for renal artery stenosis
- Monitoring of renal transplants
-
Procedure: IV administration of technetium (Tc-99m pertechnetate/gamma emitter) and measurement of its distribution in the body with a gamma camera
-
Static renal scintigraphy: a diagnostic test in which a radiotracer that is retained by the renal cortex is used to assess renal function as well as the degree of structural damage to the renal cortex
- Injection of Tc-99m DMSA (Tc-99m dimercaptosuccinic acid; an injectable radioactive gamma-emitter dye that rapidly accumulates in the renal parenchyma and very small amounts are eliminated from the kidney)
- Imaging is performed ∼ 3 hours after injection, when the dye has reached the kidneys for renal clearance.
-
Dynamic renal scintigraphy: a diagnostic test in which a radiotracer that is excreted by the kidney is used to assess renal perfusion as well as urine flow in the urinary tract
- Injection of Tc-99m MAG3 (mercaptoacetyltriglycine; a form of injectable technetium that rapidly accumulates in the renal parenchyma and is cleared almost exclusively by tubular excretion)
- Serial imaging from the time of injection until the end of the procedure (up to 30 min)
-
Static renal scintigraphy: a diagnostic test in which a radiotracer that is retained by the renal cortex is used to assess renal function as well as the degree of structural damage to the renal cortex
Voiding cystourethrogram [5]
- Description: a diagnostic procedure used to determine the degree of vesicoureteral reflux and detect morphological abnormalities
-
Indications
- Diagnosis of vesicoureteral reflux and urethral stricture
- Recurrent UTIs
- Suspected obstruction (e.g. bilateral hydronephrosis)
- Suspected bladder trauma or rupture
-
Procedure
- Radiocontrast dye is injected into the bladder by means of a urinary catheter (retrograde contrast filling of the bladder)
- Fluoroscopy is performed during voiding.
- During voiding pressure increases in the bladder and this may reveal previously hidden reflux [6]
Intravenous urography (excretory urogram, IV pyelogram) [7]
- Description: a diagnostic procedure that involves intravenous contrast agent and x-rays to provide images of the genitourinary tract
- Indication: visualization of renal excretion and the course of the ureters
- Procedure
-
Contraindications
- Hyperthyroidism
- Renal insufficiency
- Contrast medium allergy
- Multiple myeloma
CT urography
- Description: an imaging study that uses CT with intravenous contrast to assess the anatomy and, to a certain degree, function of the urinary collecting system, renal calyces, ureters, and bladder
- Indications: a first-line imaging test to assess for genitourinary abnormalities (e.g., malignancy, stricture)
- Procedure: CT with contrast dye injected intravenously
Retrograde urethrogram
- Description: a diagnostic test in which a contrast agent is injected into the urethra to evaluate for urethral injuries and disorders via x-ray
- Indication: suspected anatomical and functional lesions of the urethra (e.g., urethral stricture, injuries)
Retrograde CT cystography
- Description: imaging modality using computed tomography to visualize the bladder after retrograde filling with contrast agent
- Indication: evaluation of the bladder for postoperative leakage or rupture following trauma
- Procedure: CT after contrast dye is injected into the bladder via the urethra
Retrograde pyelography
- Description: A diagnostic procedure in which x-rays are taken as a water-soluble contrast agent is injected in the ureter via cystoscopy
-
Indication
- Contraindications to IV/CT urography
- Secondary study to confirm or further characterize findings
- Procedure
Cystoscopy
- Description: an endoscopic procedure in which a thin tube with a light and a camera is inserted through the urethra into the bladder, allowing for visualization of the urethra, bladder, and ureteral orifice
-
Indications
- Hematuria
- Suspected interstitial cystitis, gynecological malignancies, endometriosis
- Recurrent urinary tract infections
- Urinary incontinence or overactive bladder
- Urinary tract injuries (traumatic or iatrogenic)
- Urinary obstruction
- Injection of therapeutic drugs (e.g., botulinum toxin for urinary incontinence)
- Procedure: A flexible or rigid cystoscope is inserted into the urethra using an electrolyte-containing irrigation fluid or sterile water.
-
Complications
- Postprocedural hematuria and/or dysuria
- Urinary tract infection
- Iatrogenic injury to the urethra or bladder
Urinary drainage procedures
Bladder catheterization
- Description: placement of a catheter into the bladder via the urethra or percutaneously through the suprapubic abdominal wall
-
Clinical applications
- Sterile urine sample collection
- Measurement of urinary output and/or postvoid residual volume
- Bladder drainage, e.g., for urinary retention; , urinary obstruction, patients with impaired mobility
- Access for intravesical therapy, e.g., bladder irrigation, chemotherapy
- Types of bladder catheterization
Transurethral catheterization is relatively contraindicated in patients with known or suspected urethral injury or acute bacterial prostatitis.
Suprapubic catheterization
- Description: : a surgical procedure that involves insertion of a catheter through the abdominal wall with placement in the bladder
-
Indications
- Method of choice if transurethral catheterization is difficult (e.g., urethral stricture, large prostate) or contraindicated (e.g., suspected urethral trauma, recent urethral surgery, acute bacterial prostatitis)
- Often preferred for chronic bladder catheterization
-
Procedure
- Percutaneous urinary catheter insertion above the pubic symphysis
- May be used intermittently or left in place to continuously drain urine
-
Advantages
- Higher level of comfort and easier to change than a transurethral catheter
- Prevents urethral trauma and stricture formation
- Decreased incidence of catheter-associated bacteriuria
-
Contraindications
- Empty or poorly localized bladder
- Prior bladder irradiation or surgery
- Bladder cancer
- Uncorrectable coagulopathy
-
Complications
- Infection
- Peritoneal perforation
- Injury to surrounding organs
Ureteral stenting
- Description: a urologic procedure that involved insertion of a thin, hollow tube into the ureter to enable drainage of fluid from the renal pelvis into the bladder
-
Indications
- Upper urinary tract obstruction (e.g., nephrolithiasis, tumors, pregnancy)
- Ureteral injuries or fistulas with urinary leakage
- Prevention of ureteral obstruction from passing stone fragments after lithotripsy
-
Procedure
- Insertion of a double-J stent into the ureter
- Cystoscopy-guided transurethral (retrograde) placement or via percutaneous puncture of the renal pelvis under fluoroscopic guidance (antegrade)
- Stent should be exchanged every 3 to 6 months
-
Contraindications [8]
- Urinary bladder outlet obstruction (e.g., due to BPH) or urinary tract infection
- Uncorrectable coagulopathy
-
Complications
- Ureter injury
- Urinary tract infection
- Stent encrustation or displacement
Percutaneous nephrostomy [9][10]
- Description: a urologic procedure that involves the insertion of a pigtail catheter (nephrostomy tube) into the dilated renal pelvis
-
Indications
- Upper urinary tract obstruction (when ureteral stent cannot be placed)
- Ureteral injuries or fistulas
- Access for urologic procedures (e.g., percutaneous nephrolithotomy, delivery of chemotherapeutic agents)
- Antegrade pyelography
-
Procedure
- Insertion of a catheter into the renal pelvis under ultrasound guidance using the Seldinger technique
- Routine antibiotic prophylaxis within one hour before the procedure is recommended. [9]
- Catheter should be exchanged every 3 months.
- Contraindications: uncorrectable coagulopathy [10]
-
Complications
- Damage of adjacent organs
- Vascular injury and hemorrhage
- Bowel perforation
- Pleural complications (e.g., pneumothorax, hemothorax)
- Urosepsis (esp. in patients with pyonephrosis)
- Catheter encrustation or displacement
- Damage of adjacent organs
Percutaneous nephrostomy is more invasive and has a higher risk of bleeding and infection than transurethral placement of a ureteral stent.
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