Background
Cystourethrography is a radiographic examination of the bladder and the urethra, whereas cystography refers to radiographic evaluation of the bladder alone. The technique depends on contrast media being introduced into the bladder via a urethral catheter, allowing visualization of anatomic defects and workup of functional abnormalities.
Urodynamic evaluation is the standard of care for any type of voiding abnormality in order to illuminate the pathophysiology of the patient’s condition. The study guides decision-making about surgical intervention and treatment, and it indicates to physicians which patients will require closer follow-up. Videourodynamics refers to a urodynamic study with radiographic imaging and is recommended in the following settings: renal transplant, neurogenic bladder, urinary diversion, and previous irradiation or pelvic surgery.
In the setting of more advanced radiographic techniques (such as voiding urosonography), cystography may be phased out as the gold standard for imaging examination. These practice changes often depend on the setting in which they are performed. For example, retrograde computed tomography (CT) is favored in trauma workup. Despite these advances, cystography supplements urodynamic evaluation and remains prevalent as a voiding cystourethrography (VCUG) study in children.
Relevant anatomy
The bladder is a muscular organ that sits behind the pubic symphysis in the pelvis. Its function (and lack thereof) depends on a careful balance of musculoskeletal, neurologic (both autonomic and somatic), and psychological inputs that control filling and voiding. There must be coordination between detrusor muscle relaxation and contraction of the bladder neck and pelvic floor muscles, which both maintain the contents of the bladder. By the same token, detrusor contraction and sphincter relaxation facilitate the passage of urine from the bladder. Dysfunction of any part of this yin and yang results in incontinence. See the image below.
For more information about the relevant anatomy, see Bladder Anatomy.
Indications
Cystography provides additional information about and elucidates a number of bladder abnormalities, such as diverticula or fistulas, in addition to leakage and traumatic rupture. In the trauma setting, cystography is indicated in cases of gross hematuria or nonacetabular pelvic fracture in the presence of microscopic hematuria of more than 25-30 red blood cells (RBCs) per high-power field. A study of bladder injuries in 157 blunt trauma patients revealed that one third of injuries would not have been detected on the basis of gross hematuria and pelvic fracture alone. Four of 12 patients studied who ultimately suffered bladder injury presented with microscopic hematuria, compared with 8 of those 12 patients with gross hematuria. [1]
Indications for VCUG include the following:
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Follow-up evaluation of vesicoureteral reflux (VUR)
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Voiding dysfunction
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Congenital genitourinary malformations and congenital conditions known to be associated with such malformations
VCUG has traditionally been used in patients with urinary tract infection (UTI), although the practice has come under fire with regard to pediatric patients. The American Academy of Pediatrics recommends that febrile children between 2 months and 2 years of age who do not respond to antimicrobial therapy should be evaluated with ultrasonography (US) promptly and VCUG at the next earliest convenience, whereas children of the same age group who do respond should undergo US and VCUG at the earliest convenience. [2]
A patient may undergo VCUG as soon as his or her voiding pattern has returned to baseline (pre-UTI), although clinical practice has favored waiting 3-6 weeks, with antibiotic prophylaxis given in the meantime. VCUG performed in association with a UTI is valuable in its ability to detect VUR. A retrospective study revealed there was no difference in waiting 1 week versus beyond 1 week in the VUR detection rate. [3] Of note, more than half the patients slated for the later VCUG did not undergo the study.
Routine VCUG has been recommended for patients who meet any of the following criteria [4] :
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Children younger than 5 years with a febrile UTI
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Males of any age with a first UTI
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Females younger than 2 years with a febrile UTI
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Children with recurrent UTIs
A study conducted by Dalirani et al that looked at the utility of a direct radionuclide cystography (DRNC) in children with UTI and normal VCUG results demonstrated that DRNC could uncover VUR despite the normal result in children with hydronephrosis and/or UTI with fever. [5]
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Ureterocele. Early anteroposterior voiding cystourethrography (VCUG) demonstrates small ureterocele (left). Ureterocele had been seen at prior ultrasonography of bladder. On VCUG obtained after bladder filling (right), ureterocele is obscured by contrast material. Image courtesy of Fernbach SK, Feinstein KA, Schmidt MB. Pediatric voiding cystourethrography: a pictorial guide. Radiographics. 2000;20:155-16.
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Oblique voiding cystourethrogram obtained at left ureterovesical junction demonstrates primary vesicoureteral reflux (ie, reflux without underlying abnormality such as bladder diverticulum, neurogenic bladder, or bladder outlet obstruction). Image courtesy of Fernbach SK, Feinstein KA, Schmidt MB. Pediatric voiding cystourethrography: a pictorial guide. Radiographics. 2000;20:155-16.
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Posterior urethral valves. Oblique voiding cystourethrogram shows filling defect in the urethra with marked change in urethral caliber at level of defect, which indicates obstruction. Although catheter has remained in place during voiding, secondary changes crucial to diagnosis—trabeculated bladder, abnormally prominent bladder neck, and dilated and elongated posterior urethra—are clearly depicted. Image courtesy of Fernbach SK, Feinstein KA, Schmidt MB. Pediatric voiding cystourethrography: a pictorial guide. Radiographics. 2000;20:155-16.
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Voiding cystourethrogram (VCUG) in patient with bulbar urethral stricture. Graphics are superimposed on VCUG to show locations of prostate and external sphincter muscle (posterior urethra). Image courtesy of Joel Gelman, MD.
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Voiding cystourethrogram in patient with detrusor sphincter dyssynergia shows trabeculated bladder wall and lack of cone-shaped bladder neck during voiding.
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Postvoiding film shows no residual contrast material. Image courtesy of Radswiki.net.
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Gross anatomy of the bladder.
