Genitourinary Tract Fluoroscopy

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What are genitourinary fluoroscopic examinations?

Genitourinary fluoroscopic examinations are studies that require “real-time” observation using fluoroscopy so that maximal information is obtained about the anatomy and function of the structure being studied. A radiographic iodinated contrast agent is injected into the various portions of the genitourinary tract for these examinations. Examples include retrograde pyelography to evaluate the upper urinary tract, cystography or voiding cystourethrography (VCUG) to evaluate the lower urinary tract, retrograde urethrography (RUG) to evaluate the urethra, and hysterosalpingography (HSG) to evaluate the uterus and fallopian tubes.

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What is a retrograde pyelogram, and how does it differ from a urogram?

As discussed in Chapter 33 , a urogram (via intravenous urography [IVU] or computed tomographic urography [CTU]) requires intravenous administration of contrast material, after which imaging of the renal parenchyma is performed in the earlier nephrographic phase of enhancement and of the collecting system in the excretory phase of enhancement. A urogram provides physiologic information about the function of the kidneys, in addition to depicting the anatomy of the renal parenchyma and collecting systems. A retrograde pyelogram provides only anatomic information about the lumen of the collecting system and ureter, but the depiction of mucosal abnormalities is superior to that seen with urography. For performing a retrograde pyelogram, cystoscopy is initially performed by a surgeon, most commonly a urologist, and a catheter is placed through the ureterovesical junction into the renal pelvis under direct vision with a cystoscope. The patient is then transferred to the radiology department where contrast material is injected through this catheter under fluoroscopic guidance to evaluate the lumen of the pyelocalyceal system and ureter for mucosal abnormalities such as urothelial carcinoma. An alternative to placing a catheter into the collecting system is to inject contrast material directly into the ureterovesical junction through the cystoscope and obtain images in the operating room; this technique is useful if the ureter alone has to be evaluated for urothelial abnormalities but is unsuitable for complete evaluation of the collecting system ( Figure 34-1, A-B ).

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When is a retrograde pyelogram necessary?

A retrograde pyelogram is performed if the patient cannot receive an intravenous contrast material because of renal insufficiency or a history of severe adverse reaction to radiographic contrast agents. Retrograde examination can also be performed if a urogram fails to show the entire pyelocalyceal system or ureter, or to evaluate further an abnormality seen on a urogram ( Figure 34-1, C-E ).

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What is the difference between a cystogram and a voiding cystourethrogram?

A cystogram is tailored to evaluate the urinary bladder alone, whereas a voiding cystourethrogram includes evaluation of the bladder neck and urethra under fluoroscopic observation. Both studies require injection of radiographic contrast material into the urinary bladder through either an indwelling bladder drainage catheter or a catheter placed in the urinary bladder solely for the procedure. Cystography is limited to obtaining images of the bladder, whereas in voiding cystourethrography (VCUG), the catheter is removed after the bladder has been distended with contrast material, and the patient voids under fluoroscopic observation so that the bladder neck and urethra can also be evaluated.

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What are the indications for cystography and VCUG?

These studies are performed to evaluate the anatomy of the bladder and urethra in patients with voiding dysfunction or recurrent urinary tract infection (UTI) ( Figure 34-2 ), to assess for a leak or fistula from the bladder after surgery or abdominal trauma ( Figure 34-3 ), to evaluate for presence of vesicoureteral reflux (VUR) in patients with recurrent or refractory UTI, or to evaluate urinary incontinence.

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What is a retrograde urethrogram?

A retrograde urethrogram is a study used primarily to evaluate the anterior urethra in men ( Figure 34-4 ). 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.

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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.

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How is the female urethra evaluated?

The entire female urethra is well depicted on VCUG (see Figure 34-3 ). The short length of the female urethra makes RUG a difficult and unnecessary procedure in women.

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What is a loopogram?

In patients who have undergone cystectomy (usually performed for muscle-invasive bladder cancer), the ureters are connected to a loop of ileum known as an ileal conduit. The ileal conduit is excluded from the intestinal stream and is connected to the anterior abdominal wall through a stoma; a urinary drainage bag is applied to the stoma site to collect urine. A loopogram is performed to evaluate the conduit and the upper urinary tracts. A catheter is placed in the ileal conduit, and contrast material is injected under fluoroscopic guidance until it refluxes in a retrograde fashion into the ureters and pyelocalyceal systems ( Figure 34-5 ).

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What is a pouchogram?

Urinary pouches are an alternative to an ileal conduit, for urine storage and drainage in patients who have undergone cystectomy; these pouches allow urine storage similar to the bladder, do not require a urinary drainage bag, are periodically emptied by either catheterization or voiding, and are therefore sometimes referred to as neo-bladders. They are of two main varieties: cutaneous and orthotopic. Many such pouches have been developed, and the names assigned to the pouches are assigned by the surgeon who developed them or the institution where they were developed. For instance, an “Indiana pouch,” a form of cutaneous continent pouch, was developed at Indiana University in the United States, while a “Studer pouch,” an orthotopic urinary pouch, was developed by Dr. Studer ( Figure 34-6 ).

It is not possible to detail the many continent pouches that are used in clinical practice currently. General principles are that the pouches are constructed of detubularized bowel and are made to have enough capacity to hold ≈500 ml or more of urine, and the ureters are anastomosed to the pouches. In a cutaneous pouch such as the Indiana pouch, the cecum and ascending colon are often used to form the pouch, and the patient catheterizes the pouch through a stoma made of a segment of the terminal ileum. In an orthotopic pouch, ileum is used to construct the pouch, which is anastomosed to the urethra so that the patient can void per urethra by straining and pushing on the pouch.

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