Sonography in the evaluation of the male anterior urethra

Ultrasound of the male anterior urethra

Imaging of the anterior male urethra has traditionally been performed by fluoroscopic contrast urethrography. While providing easily interpretable images, this technique has a number of disadvantages associated with it. An alternative approach is to use ultrasound to assess the lumen of the urethra and the periurethral tissues. Here we describe the development of urethral ultrasound and the ascending and descending urethral ultrasound techniques employed in our institution with reference to commonly and uncommonly encountered pathologies. We also identify common pitfalls and how to avoid them.

Imaging of male urethra

The male urethral imaging and pathology is not widespread in the radiology literature because this part of the urinary tract is easily studied by urologists with clinical or endoscopic examinations. Ultrasonography and MR imaging are increasingly being used in association with voiding cystourethrography and retrograde urethrography. The posterior urethra is being studied with voiding cystourethrography or voiding sonography which allows the detection of bladder neck pathology, post-surgical stenosis, and neoplasms. The functional aspects of the bladder neck and posterior urethra can be monitored continuously in patients with neuromuscular dysfunction of the bladder. The anterior urethral anatomy and pathology is commonly explored by retrograde urethrography, but recently sonourethrography and MR imaging have been proposed, distending the lumen with simple saline solution instead of iodinated contrast media. They are being used to study the urethral mucosa and the periurethral spongy tissue which can be involved in the urethral pathologies such as strictures, diverticula, trauma, and tumors. Imaging has an important role to play in the study of the diseases of the male urethra since it can detect pathology not visible on urethroscopy. The new imaging techniques in this area, such as sonography and MR, can provide adjunct information that cannot be obtained with other modalities.

Descending urethral ultrasound of the native and reconstructed urethra in patients with hypospadias

A retrospective study, over a 7 year period, examining the use of descending urethral ultrasound in corrected and uncorrected hypospadias was performed. 15 examinations were performed on 14 patients; 12 patients had undergone previous surgery for hypospadias, ranging from urethral reconstruction to stricture dilatation. Eight strictures, four irregular urethras, two normal post-operative urethras and one urethral valve were demonstrated. All the clinically significant abnormalities (those which impaired the flow of urine) demonstrated by ultrasound were confirmed with subsequent urethroscopy or contrast urethrography. This small series illustrates the application of descending urethral ultrasound in patients with hypospadias who are difficult to examine with more conventional radiographic techniques.

Ultrasound of the male anterior urethra

Ascending and descending techniques are used to demonstrate the male anterior urethra. The authors developed an ultrasound approach with the patient compressing his own urethra manually during voiding to achieve distension of the urethra with urine. The subsequent sonourethrography is more accurate than conventional fluoroscopic contrast studies in defining urethral filling defects and is as accurate for the demonstration of strictures. The technique has replaced contrast urethrography at the authors' institutions for the routine evaluation of the anterior urethra.

Imaging of the male urethra for stricture disease

Imaging of the urethra for suspected stricture disease should initially consist of conventional imaging with a dynamic RUG. It is easy to perform and detects clinically relevant strictures involving the anterior urethra and those with extension into the membranous urethra. Additional studies, including antegrade imaging, sonographic urethrography, and MRI are best used in conjunction with RUG as clinically indicated to better define the extent of disease and assist in guiding reconstruction. Post-operatively, VCUG is appropriate to evaluate complete healing and adequacy of repair. Sonourethrography is a simple technique that provides a dynamic, precise assessment of anterior urethral strictures. It is best employed as a staging study in men with known symptomatic strictures in whom the need for operative therapy is clear. For short bulbar strictures ultrasound is more accurate in measuring stricture length than conventional radiographic RUG and is therefore helpful in determining whether to excise or graft. For long or complex strictures assessment of the stricture's diameter may be helpful in determining flap width or in identifying the focal urethral segments to be excised. The simplicity, precision, and availability of sonography along with the absence of radiation exposure make sonourethrography a valuable staging tool for the reconstructive urologist. MRI is valuable for defining the distorted pelvic anatomy that is frequently associated with posterior urethral strictures resulting from trauma. By determining the location of the prostate and the length of the prostatomembranous defect, MRI may help determine whether a transperineal or transpubic approach for reconstruction is necessary.