In this iconographic essay we illustrate the key imaging features of urethral and bladder diseases in voiding cystourethgraphy.This essay is organized as follows: (a) voiding cystourethgraphy technique,(b) normal anatomy of the urethra and bladder,(c) traumatic injuries,(d) acquired inflammatory diseases,(e) urethral strictures,(f) acquired urethral and bladder diverticula,(g) vesicoureteral reflux,(h) prolapsed bladder,and (i) congenital anomalies.
Voiding cystography technique (Fig 1)
·VCUG examination is performed combining fluoroscopic and radiographic imaging
·We start with an abdominal radiography
·Aseptic catheterization of the bladder,followed by application of nonionic iodinated contrast media via a catheter.
·Intermittent screening of the patient on fluoroscopy,while distending the bladder with contrast,is necessary to check for a ureterocoele or VUR
·After the bladder is filled to its capacity (which will vary as per age of patient) the patient is now asked to void
The following projections should be acquired keeping within the ALARAprinciple(As Low As Reasonably Achievable):
1. When the bladder is filled:
· Frontal view for demonstration of the presence or absence of VUR.
· Both left and right obliques to demonstrate bilateral vesicoureteric junctions.
2. during voiding (oblique in male patients)
3. post void film to check for a ureterocoele.
Normal anatomy of the urethra and bladder (Fig 2)
While retrograde opacification:
·The membranous urethra appears narrow because of its resistance,but with a progressive taper.
·The prostatic urethra remains tapered and does not distend.
·Only the spongy urethra is distended.
· Bladder neck still closed.
During voiding: (Fig3)
· The perineal and the navicular urethra are distended.
·Bladder neck is enlarged.
Traumatic injuries
The most common injury by far is that of the posterior urethra.Such injury occurs in 3%–25% of patients with pelvic fractures [1].
Injury of the female urethra is rarer (<6% of female pelvic fractures) than that of the male urethra because of shorter length,internal location,increased elasticity,and less rigid attachment of the urethra to the adjacent pubic bones [2].
Urethral strictures (Fig 4)
In general,the term urethral stricture refers to a fibrous scarring of the anterior urethra caused by collagen and fibroblast proliferation [3].
Acquired urethral and bladder diverticula (Fig 5)
Bladder diverticulum is a herniation of the bladder mucosa through a defect in a muscle layer.
Urethral diverticulum is is a focal outpouching of the
urethra.
Vesicoureteral reflux
Suspicion of VUR consists the indication of the majority of VCUG requests.The presence of VUR should be documented along with the characterization of the degree of reflux,according to the International Refulx system [4] (Fig 6,7):
GRADE I: Reflux into the ureter
GRADE II: Reflux into the ureter and into thepyelocaleceal system with no signs of dilatation
GRADE III: Reflux into the ureter and into thepyelocaleceal system which appear mildly dilated.
GRADE IV: Reflux into the ureter with tortuous ureter appearanceand into the pyelocaliceal system which is dilated and has blunted forniceal angles
GRADE V: Reflux into ureter which appears markedly dilated and tortuous,and into the pyelocaleceal system with obliteration of the forniceal angles and the pappillary impressions.
Prolapsed bladder (Fig 8)
A cystocele receives one of three grades depending on how far a woman’s bladder has dropped into her vagin*:
Grade 1: mild,when the bladder drops only a short way into the vagin*
Grade 2: moderate,when the bladder drops far enough to reach the opening of the vagin*
Grade 3: most advanced,when the bladder bulges out through the opening of the vagin*
Detrusor-external sphincter dyssynergia (Fig 9)
Detrusor-external sphincter dyssynergia (DESD) is a consequence of a neurological pathology such as spinal injuryor multiple sclerosis which disrupts central nervous system regulation of the micturition (urination) reflex resulting in dyscoordination of the detrusor muscles of the bladder and the male or female external urethral sphincter muscles.In normal lower urinary tract function,these two separate muscle structures act in synergistic coordination.But in this neurogenic disorder,the urethral sphincter muscle,instead of relaxing completely during voiding,dyssynergically contracts causing the flow to be interrupted and the bladder pressure to rise.
Congenital anomalies
Posterior urethral valves (Fig 10)
Posterior urethral valves are the most common obstructive anomaly in male children.Voiding cystourethrography is the only procedure that confirms PUV,showing a filling defect followed by reduced caliber of urethra between disproportionately dilated posterior urethra and a narrow anterior urethra,associated with secondary changes- bladder neck hypertrophy,and trabeculation or sacculation of the bladder.
Megaureter
Any ureter with a diameter over 8 mm is considered abnormal,and may be described as megaureter.Primary or secondary,it usually belongs to one of the three groups: refluxing,obstructive or non-refluxing non-obstructive megaureter.
Duplicated ureter
Duplicated ureter is the most common congenital abnormality of ureter,arising with duplicated collecting system,presented as two pyelocaliceal systems draining a single kidney,continuing into a bifid (ureter fissus,ureter bifidus,partial duplication) or double ureter (with a separate ureteric orifice each).Possible complications are obstruction,ureterocele,or vesicoureteral reflux –in which case it can be confirmed by VCUG.
Ureterocele (Fig 11)
Ureterocele denotes a congenital dilatation of the distal part of the ureter,protruding into the bladder when filled with urine.
Bladder exstrophy (also known as ectopia vesicae) (Fig12)
Is a congenital anomaly that exists along the spectrum of the exstrophy-epispadias complex and most notably involves protrusion of the urinary bladder through a defect in the abdominal wall.
