From the Guidelines
A urologist can determine the length of a urethral stricture primarily through retrograde urethrography (RUG) and voiding cystourethrography (VCUG), which are the gold standard imaging techniques, as stated in the most recent guideline amendment 1. These contrast-based studies provide detailed visualization of the urethral lumen, allowing measurement of the stricture's length and assessment of its location and severity.
Key Points to Consider
- Urethroscopy is another valuable method where a small camera is inserted into the urethra to directly visualize the stricture, though it may underestimate stricture length in severe narrowing.
- Ultrasound techniques, including transrectal ultrasound for posterior strictures and penile ultrasound for anterior strictures, offer additional information about the surrounding tissues and stricture depth.
- In some cases, MRI may be used for complex strictures, particularly in the posterior urethra.
- For comprehensive evaluation, urologists often combine these methods, typically starting with RUG/VCUG for initial assessment, followed by urethroscopy during treatment planning, as recommended by the American Urological Association guideline 1 and its amendment 1. This multi-modal approach ensures accurate measurement of stricture length, which is crucial for selecting the appropriate surgical technique and predicting treatment outcomes, especially for patients with short (<2cm) bulbar urethral stricture who may be treated endoscopically after a period of urethral rest 1.
From the Research
Determining Urethral Stricture Length
To determine the length of a urethral stricture, urologists can use various imaging techniques. The choice of technique depends on the location and complexity of the stricture.
- Retrograde Urethrography (RUG): This is the current gold standard for diagnosing and staging urethral strictures 2. RUG can be combined with voiding cystourethrogram (VCUG) to better visualize the posterior urethra or complex distraction defects.
- Sonourethrography (SU): This technique provides a dynamic, precise assessment of anterior urethral strictures and is useful for measuring stricture length 3, 4. SU is a valuable adjunct to RUG and can be used intraoperatively.
- Magnetic Resonance Urethrography: This technique is effective for evaluating obliterative urethral strictures and provides accurate measurements of stricture length 5.
- Cross-sectional Imaging: Computed tomography (CT) or magnetic resonance urethrography can provide additional three-dimensional information on anatomic structures and their relations, and can be useful in complex clinical scenarios 2.
Comparison of Imaging Techniques
Studies have compared the accuracy of different imaging techniques in measuring urethral stricture length.
- A study found that RUG + VCUG may underestimate urethral stricture length, particularly in the membranous and bulbar regions 6.
- Another study found that sonourethrography is a valuable diagnostic tool in the evaluation of anterior urethral stricture, with a sensitivity of 94% and accurate measurements of stricture length 3.
- Magnetic resonance urethrography has been shown to be more accurate than conventional RUG + VCUG in measuring stricture length 5.
Clinical Application
The choice of imaging technique depends on the clinical scenario and the location of the stricture.
- For anterior urethral strictures, sonourethrography is a useful adjunct to RUG 3, 4.
- For posterior urethral strictures, magnetic resonance urethrography can provide valuable information on the location and length of the stricture 5, 4.
- For complex strictures, a combination of imaging techniques may be necessary to accurately determine the length and location of the stricture 2, 6.