Diagnostic investigations and procedures in urology

Last updated: November 1, 2023

Summarytoggle arrow icon

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 studiestoggle arrow icon

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.


  • Description
    • Assesses bladder pressure during filling
    • Determines detrusor and bladder function (activity, sensation, capacity, and compliance)
  • Indications
  • 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


  • Description: an objective, noninvasive test used in the evaluation of patients with suspected bladder outlet obstruction
  • Indications
  • 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

Pressure-flow study [1]

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
  • 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

Postvoid residual volume


  • 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.


Imaging techniquestoggle arrow icon


The bladder should be full to visualize pelvic structures.



Renal scintigraphy

  • Description: a diagnostic procedure in which radioisotopes are used to assess the anatomy and function of the kidneys
  • Indications
  • 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
    • 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)

Voiding cystourethrogram [5]

Intravenous urography (excretory urogram, IV pyelogram) [7]

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

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
    • Contrast medium is injected into the ureter using a catheter.
    • Serial x-rays of areas of interest are taken.

Cystoscopytoggle arrow icon

Urinary drainage procedurestoggle arrow icon

Bladder catheterization

Transurethral catheterization is relatively contraindicated in patients with known or suspected urethral injury or acute bacterial prostatitis.

Suprapubic catheterization

Ureteral stenting

Percutaneous nephrostomy [9][10]

Percutaneous nephrostomy is more invasive and has a higher risk of bleeding and infection than transurethral placement of a ureteral stent.

Referencestoggle arrow icon

  1. Makramalla A, Zuckerman D. Nephroureteral Stents: Principles and Techniques. Semin Intervent Radiol.. 2011; 28 (04): p.367-379.doi: 10.1055/s-0031-1296079 . | Open in Read by QxMD
  2. Dagli M, Ramchandani P. Percutaneous nephrostomy: technical aspects and indications. Semin Intervent Radiol. 2011; 28 (4): p.424-437.doi: 10.1055/s-0031-1296085 . | Open in Read by QxMD
  3. Pabon-Ramos WM, Dariushnia SR, Walker TG, et al. Quality Improvement Guidelines for Percutaneous Nephrostomy. J Vasc Interv Radiol.. 2016; 27 (3): p.410-414.doi: 10.1016/j.jvir.2015.11.045 . | Open in Read by QxMD
  4. Nitti VW. Pressure flow urodynamic studies: The gold standard for diagnosing bladder outlet obstruction. Rev Urol. 2005; 7 (Suppl 6): p.S14-S21.
  5. Whitfield HN. Urological evaluation. BMJ. 2006; 333 (7565): p.432–435.doi: 10.1136/bmj.333.7565.432 . | Open in Read by QxMD
  6. Chernecky CC, Berger BJ. Laboratory Tests and Diagnostic Procedures. Elsevier Health Sciences ; 2012
  7. Chapple CR, MacDiarmid SA, Patel A. Urodynamics Made Easy. Elsevier Health Sciences ; 2012
  8. Voiding cystourethrography. Updated: January 16, 2017. Accessed: January 16, 2017.
  9. Dunnick R, Sandler C, Newhouse J. Textbook of Uroradiology. Lippincott Williams & Wilkins ; 2012
  10. Intravenous Urography. Updated: January 1, 2017. Accessed: November 19, 2017.
  11. Warrell DA, Cox TM, Firth JD. Oxford Textbook of Medicine. Oxford University Press ; 2015
  12. Adam A, Dixon AK, Gillard JH, Schaefer-Prokop C, Grainger RG, Allison DJ. Grainger & Allison's Diagnostic Radiology E-Book. Elsevier Health Sciences ; 2014
  13. Reynard J, Brewster S, Biers S. Oxford Handbook of Urology. OUP Oxford ; 2013

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