Two of the most important tests to diagnose and evaluate a urethral stricture are the retrograde urethrogram (RUG) and a cystoscopy. The retrograde urethrogram can be done by a radiologist or by a urologist. In our experience the information gained when an urologist does the RUG is usually more helpful then when done by a radiologist, but many urologist may not do the RUG because they lack the x-ray facilities for the test in their office. In our office, we are able to do fluoroscopy and, consequently, retrograde urethrograms in the office to diagnose and evaluate urethral strictures. The RUG is typically done by placing the patient on his side with a bottom leg bent and the top leg straight. The penis is put on mild stretch and contrast is gently injected into the urethra using either a small catheter or a specially designed syringe. As dye is injected into the urethra, multiple x-ray images are take to look for narrowing suggestive of a stricture.
Urologists specializing in urethral reconstruction know what to look for and can shift the position of the patient during the study to maximize important information to plan the best surgery to correct the urethral stricture. When a radiologist does this test, however, they may not be aware of the diagnostic needs of the surgeon. It is not uncommon for us to need to repeat the retrograde urethrogram for a patient who has been diagnosed with urethral strictures because of the poor quality of the original films done by a radiologist.
The retrograde urethrogram provides critical information about the length and location of the stricture as well as the extent of spongiofibrosis (a term we’ve previously discussed) and the density of the stricture. The extent of spongiofibrosis has a great impact on counseling patients as to the best type of surgery to correct the stricture.
Occasionally, however, the patient may have multiple dense strictures or may have a stricture in the back (posterior) portion of the urethra which are not very well visualized by retrograde urethrogram. In patients with more than one stricture (termed synchronous urethral stricture) the dye may not get past the first stricture and the extent of the patient’s stricture disease can be significantly underestimated. In these cases, a voiding cystourethrogram (VCUG) in addition to the retrograde urethrogram can be a useful test to evaluate the patient’s stricture, particularly if surgery is anticipated for the patient. The voiding cystourethrogram is done by placing a suprapubic tube, or a catheter that enters the abdomen below the belly button and goes straight into the bladder. Dye is placed through the catheter directly into the bladder and the patient is asked to urinate while x-rays are obtained. The voiding cystourethrogram can help visualize the proximal portion of the urethra when the retrograde urethrogram alone is inadequate.
Rarely, we have found that an ultrasound done of the urethra may also be helpful. This was particularly helpful if we are concerned that the patient has more extensive spongiofibrosis than may be apparent on the retrograde urethrogram. We typically will do the ultrasound of the urethra prior to surgery to better anticipate the type of surgery the patient will need. In our next urethral stricture blog post we’ll discuss the usefulness of a cystoscopy for diagnosing urethral strictures.