Voiding cystourethrography
Updates to Article Attributes
Voiding cystourethrography (VCUG), also known as a micturating cystourethrography (MCU), is a fluoroscopic study of the lower urinary tract in which contrast is introduced into the bladder via a catheter. The purpose of the examination is to assess the bladder, urethra, postoperative anatomy and micturition in order to determine the presence or absence of bladder and urethral abnormalities, including vesicoureteric reflux (VUR).
It is more commonly performed in the paediatric population than adults.
Indications
As per American College of Radiology (ACR) and Society for Paediatric Radiology (SPR) guidelines clinical indications for voiding cystourethrography include, but are not limited to:
- urinary tract infection
- dysuria
- dysfunctional voiding
- hydronephrosis and/or hydroureter
- bladder outlet obstruction
- haematuria
- trauma
- urinary incontinence
- neurogenic dysfunction of the bladder, e.g. spinal dysraphism
- congenital anomalies of the genitourinary tract
- postoperative evaluation of the urinary tract
Fever ≥39°C (102.2°F) and a pathogen other than E. coli after a first febrile urinary tract infection in a child is also considered a strong indication due to an increased risk of renal scarring in this population 2.
Procedure
Formulas used to estimateThe estimated age-adjusted bladder capacity can be calculated using 4,5:
Practical
- linear equations:
-Less than one-
<1 year
1.Weight (Kg)-
weight [kg] x 7 =
Capacitycapacity (mL) - 2
.(2.5 × agein months)[months] + 38 =Capacitycapacity (mL)Less than two
-
weight [kg] x 7 =
-
<2 years
3.: (2 x agein years(years) + 2) x 30 =Capacitycapacity (mL)More than two -
>2 years
4.: ({Age in years(age [years]/2})+6) x 30 =Capacitycapacity (mL)Nonlinear model was the most accurate formula for all ages.5.[4
-
<1 year
-
non-linear equations:
-
(4.5 x age
in years (0.40)][years]0.40) x 30 = capacity[ounces[mL]To convert ounces to mL multiply by 30.Girls are considered to have larger capacities than boys, was not significantly different between them.
-
(4.5 x age
Technique
- the bladder is filled with contrast medium using an infant feeding tube under aseptic precautions; a Foley catheter can be used for older children
- intermittent screening of the patient on fluoroscopy, while distending the bladder with contrast, is necessary to check for a ureterocele 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 ALARA principle:
- AP with full bladder for demonstration of the presence or absence of VUR.
-
bothBoth obliques to demonstrate bilateral vesicoureteric junctions. -
post voidPost-void film to check for a ureterocele.
VCUG/MCU vs RUG/ASU
While the urethra is well outlined in both procedures, RUG/ASU is better to visualise anterior urethral abnormalities and VCUG is better for posterior urethral abnormalities. Additionally, VCUG is carried for detection of bladder abnormalities and vesicoureteric reflux (VUR). VCUG is the initial examination of choice after metoidioplasty or phalloplasty in transgender males (female to male) 3.
-</ul><p>Fever ≥39°C (102.2°F) and a pathogen other than <em>E. coli</em> after a first febrile urinary tract infection in a child is also considered a strong indication due to an increased risk of renal scarring in this population <sup>2</sup>.</p><h4>Procedure</h4><p><strong>Formulas used to estimate age-adjusted bladder capacity </strong></p><p>Practical linear equations:- </p><p>Less than one year</p><p><!--[if !supportLists]-->1. <!--[endif]-->Weight (Kg) x 7 = Capacity (mL)</p><p><!--[if !supportLists]-->2. <!--[endif]-->(2.5 × age in months) + 38 = Capacity (mL)</p><p>Less than two years</p><p><!--[if !supportLists]-->3. <!--[endif]-->(2 x age in years + 2) x 30 = Capacity (mL)</p><p>More than two years</p><p><!--[if !supportLists]-->4. <!--[endif]-->({Age in years/2}+6) x 30 = Capacity (mL)</p><p> </p><p>Nonlinear model was the most accurate formula for all ages.</p><p><!--[if !supportLists]-->5. <!--[endif]-->[4.5 x age in years (0.40)] = capacity [ounces]</p><p>To convert ounces to mL multiply by 30.</p><p>Girls are considered to have larger capacities than boys, was not significantly different between them.</p><h5>Technique</h5><ul>- +</ul><p>Fever ≥39°C (102.2°F) and a pathogen other than <em>E. coli</em> after a first febrile urinary tract infection in a child is also considered a strong indication due to an increased risk of renal scarring in this population <sup>2</sup>.</p><h4>Procedure</h4><p>The estimated age-adjusted bladder capacity can be calculated using <sup>4,5</sup>:</p><ul>
- +<li>linear equations:<ul>
- +<li><1 year<ul>
- +<li>weight [kg] x 7 = capacity (mL)</li>
- +<li>2.5 × age [months] + 38 = capacity (mL)</li>
- +</ul>
- +</li>
- +<li><2 years: (2 x age (years) + 2) x 30 = capacity (mL)</li>
- +<li>>2 years: ((age [years]/2)+6) x 30 = capacity (mL)</li>
- +</ul>
- +</li>
- +<li>non-linear equations:<ul><li>(4.5 x age [years]<sup>0.40</sup>) x 30 = capacity [mL]</li></ul>
- +</li>
- +</ul><h5>Technique</h5><ul>
-<li>both obliques to demonstrate bilateral vesicoureteric junctions.</li>-<li>post void film to check for a ureterocele.</li>- +<li>Both obliques to demonstrate bilateral vesicoureteric junctions.</li>
- +<li>Post-void film to check for a ureterocele.</li>
References changed:
- 4. Kaefer M, Zurakowski D, Bauer SB, Retik AB, Peters CA, Atala A, Treves ST. Estimating normal bladder capacity in children. (1997) The Journal of urology. 158 (6): 2261-4. <a href="https://doi.org/10.1016/s0022-5347(01)68230-2">doi:10.1016/s0022-5347(01)68230-2</a> - <a href="https://www.ncbi.nlm.nih.gov/pubmed/9366371">Pubmed</a> <span class="ref_v4"></span>
- 5. Guerra LA, Keays MA, Purser MJ, Wang SY, Leonard MP. Pediatric cystogram: Are we considering age-adjusted bladder capacity?. (2018) Canadian Urological Association journal = Journal de l'Association des urologues du Canada. <a href="https://doi.org/10.5489/cuaj.5263">doi:10.5489/cuaj.5263</a> - <a href="https://www.ncbi.nlm.nih.gov/pubmed/29940135">Pubmed</a> <span class="ref_v4"></span>
- Estimating normal bladder capacity in children, M Kaefer 1, D Zurakowski, S B Bauer, A B Retik, C A Peters, A Atala, S T Treves J Urol. 1997 Dec;158(6):2261-4. doi: 10.1016/s0022-5347(01)68230-2. Pediatric cystogram: Are we considering age-adjusted bladder capacity? Luis A Guerra, Melise A Keays, M J Purser, S Y Wang , Michael P Leonard. Can Urol Assoc J . 2018 Jun 19;12(12):378-381.
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