What is a retrograde urethrogram?
A retrograde urethrogram is a study used primarily to evaluate the anterior urethra in men. The male urethra is divided into two portions: the posterior urethra, consisting of the prostatic and membranous urethra, and the anterior urethra, consisting of the bulbar and pendulous urethra. The external urethral sphincter, located in the urogenital diaphragm, demarcates the posterior urethra from the anterior urethra. The posterior urethra has smooth muscle that relaxes when the detrusor muscle contracts during voiding and is best seen on VCUG. Although visualized on VCUG, the anterior urethra is better evaluated by retrograde urethrography (RUG), which is performed by placing a Foley catheter in the tip of the penis and injecting contrast material under fluoroscopic guidance. The urethra is usually opacified only to the level of the external sphincter on a retrograde urethrogram, because the sphincter is closed in the nonvoiding state, and contrast material cannot flow proximal to the closed sphincter.
What are the indications for a retrograde urethrogram?
The most common indication is to evaluate for a possible urethral stricture in a patient with a decreased force of urinary stream or a split stream; the procedure is also performed after repair of a urethral stricture to evaluate healing and to exclude a leak from the surgical site. Another indication is in a patient with trauma to the perineum, such as a straddle injury, or a pelvic fracture, which is usually sustained in a motor vehicle collision. Retrograde urethrograms are also useful in patients with suspected fistulae arising from the urethra, such as in a postoperative patient, in patients with inflammatory bowel disease, or after radiation therapy to the prostate gland.