Vesicoureteric_Reflux_Flashcards
What is vesicoureteric reflux (VUR)?
VUR is the abnormal backflow of urine from the bladder into the ureter and kidney. It is a relatively common abnormality of the urinary tract in children and predisposes to urinary tract infection (UTI), being found in around 30% of children who present with a UTI.
Why is it important to investigate for VUR in children following a UTI?
As around 35% of children develop renal scarring, it is important to investigate for VUR following a UTI.
What is the pathophysiology of VUR?
Ureters are displaced laterally, entering the bladder in a more perpendicular fashion than at an angle, resulting in a shortened intramural course of the ureter. Therefore, the vesicoureteric junction cannot function adequately.
What are the possible presentations of VUR?
Antenatal period: hydronephrosis on ultrasound. Recurrent childhood urinary tract infections. Reflux nephropathy, which is the commonest cause of chronic pyelonephritis. Renal scar may produce increased quantities of renin causing hypertension.
How is VUR normally diagnosed?
VUR is normally diagnosed following a micturating cystourethrogram. A DMSA scan may also be performed to look for renal scarring.
What are the grades of VUR?
Grade I: Reflux into the ureter only, no dilatation. Grade II: Reflux into the renal pelvis on micturition, no dilatation. Grade III: Mild/moderate dilatation of the ureter, renal pelvis and calyces. Grade IV: Dilation of the renal pelvis and calyces with moderate ureteral tortuosity. Grade V: Gross dilatation of the ureter, pelvis and calyces with ureteral tortuosity.
summarise VUR
Vesicoureteric reflux
Vesicoureteric reflux (VUR) is the abnormal backflow of urine from the bladder into the ureter and kidney. It is a relatively common abnormality of the urinary tract in children and predisposes to urinary tract infection (UTI), being found in around 30% of children who present with a UTI. As around 35% of children develop renal scarring it is important to investigate for VUR in children following a UTI
Pathophysiology of VUR
ureters are displaced laterally, entering the bladder in a more perpendicular fashion than at an angle
therefore shortened intramural course of the ureter
vesicoureteric junction cannot, therefore, function adequately
Possible presentations
antenatal period: hydronephrosis on ultrasound
recurrent childhood urinary tract infections
reflux nephropathy
term used to describe chronic pyelonephritis secondary to VUR
commonest cause of chronic pyelonephritis
renal scar may produce increased quantities of renin causing hypertension
Investigation
VUR is normally diagnosed following a micturating cystourethrogram
a DMSA scan may also be performed to look for renal scarring
The table below summarises the grading of VUR
Grade
I Reflux into the ureter only, no dilatation
II Reflux into the renal pelvis on micturition, no dilatation
III Mild/moderate dilatation of the ureter, renal pelvis and calyces
IV Dilation of the renal pelvis and calyces with moderate ureteral tortuosity
V Gross dilatation of the ureter, pelvis and calyces with ureteral tortuosity
A 1-year-old girl is investigated for recurrent urinary tract infections. A micturating cystourethrogram is ordered:
What does this image demonstrate?
Vesicoureteric reflux
Horseshoe kidney
Paediatric urolithiasis
Duplex collecting system
Isolated right-sided hydronephrosis
Vesicoureteric reflux
This image demonstrates grade V vesicoureteric reflux - gross dilatation of the ureter, pelvis and calyces with ureteral tortuosity. A DMSA scan is needed to identify renal scarring.
What is the investigation of choice to diagnose vesicoureteric reflux?
CT
Abdominal x-ray
DMSA
Micturating cystourethrogram
Ultrasound
Micturating cystourethrogram
The correct answer is Micturating cystourethrogram. This is an imaging test that involves filling the bladder with a contrast material and then taking x-rays while the patient urinates to visualise any reflux of urine back up into the ureters or kidneys. It is considered the gold standard for diagnosing vesicoureteric reflux, as it provides detailed images of both the lower and upper urinary tract, and allows direct visualisation of any retrograde flow of urine.
CT (Computed Tomography) scans are not typically used in the diagnosis of vesicoureteric reflux. While they can provide detailed images of the urinary tract, they do not allow for real-time visualisation of urine flow, which is crucial in diagnosing this condition. Moreover, CT scans expose patients to higher levels of radiation than other imaging techniques, making them less suitable for routine use in this context.
Abdominal x-ray does not provide enough detail to diagnose vesicoureteric reflux. This modality only gives a general overview of abdominal structures, and cannot accurately visualise the urinary tract or detect retrograde flow of urine.
A DMSA (dimercaptosuccinic acid) scan is a type of nuclear medicine imaging test that evaluates kidney function and structure. It can identify kidney damage or scarring that might have resulted from vesicoureteral reflux but does not directly show if reflux is present. Therefore, while it may be useful in assessing complications or sequelae of this condition, it cannot confirm its diagnosis.
Finally, an ultrasound can give information about anatomical abnormalities and may suggest vesicoureteral reflux by showing dilated ureters or renal pelvises. However, it cannot definitively diagnose vesicoureteral reflux as it does not demonstrate the actual passage of urine from the bladder into ureters during voiding which is seen on a micturating cystourethrogram. Ultrasound has also high false-negative rates for detecting VUR especially when compared with micturating cystourethrogram.
A 4-year-old boy with recurrent urinary tract infections is referred to the paediatric team due to worries over reflux nephropathy.
Which of the following is the investigation of choice when it comes to diagnosing this condition?
CT of the kidneys, ureters and bladder
Intravenous pyelogram
Micturating cystography
Renal ultrasound
Renal biopsy
Micturating cystography
Micturating cystography is the investigation of choice for reflux nephropathy
This question is asking about the options of imaging in suspected reflux nephropathy. Reflux nephropathy is commonly caused by recurrent urinary tract infections, most often in younger children. Urine flows backwards from the bladder toward the kidneys and over time causes scarring.
A micturating cystogram is the investigation of choice as this uses contrast to image this urinary backflow and will show at what level the urine refluxes to.
While all of the other investigations could be used in imaging of renal pathology, and some may even be used in the workup of a case like this, the most definitive and thus best imaging modality for diagnosis, is a micturating cystogram.
A 5-month-old is brought by her mother to the GP with reduced wet nappies and poor urine flow. You note from her records she has attended for multiple urinary tract infections in the past 2 months. A urine dipstick today also shows +leucocytes and ++nitrites, so you send her urine for culture and microscopy.
Her blood from 1 month ago shows:
Na+ 138 mmol/L (135 - 145)
K+ 3.9 mmol/L (3.5 - 5.0)
Bicarbonate 26 mmol/L (22 - 29)
Urea 8.0 mmol/L (2.0 - 7.0)
Creatinine 130 µmol/L (55 - 120)
You refer her for specialist assessment.
What is the diagnostic investigation for the most likely underlying condition?
Bladder ultrasound scan
CT abdomen and pelvis
MRI abdomen and pelvis
Micturating cystography
Technetium-labelled renal scan
Micturating cystography is the investigation of choice for reflux nephropathy
The correct answer is micturating cystography. Given this patient’s history of recurrent urinary tract infections at a very early age and raised creatinine on blood tests, the most likely cause is vesicoureteric reflux (VUR). A micturating cystography allows visualisation of the degree of VUR, as a dye can be inserted through a catheter and its course is followed through repeated X-ray images during bladder contraction and relaxation. Primary VUR occurs when the segment of the ureter within the bladder wall is shorter than normal as the ureters enter the bladder at a more perpendicular angle than normal. This results in urine refluxing back up the ureter and sometimes up to the kidney predisposing to urinary tract infections. With VUR, repeated reflux can also result in reflux nephropathy and renal scarring.
Bladder ultrasound scan is incorrect because this does not allow an accurate assessment of VUR. Renal ultrasound can be useful to identify scarring and can be done as a complementary assessment to micturating cystography, but bladder ultrasound alone is less sensitive. The question is asking for a diagnostic investigation of the likely diagnosis therefore the answer is micturating cystography.
CT abdomen and pelvis is incorrect because whilst it provides good anatomical information of both the bladder and kidney it does not allow accurate assessment of the degree of reflux from the bladder into the ureters during contraction or bladder relaxation. Micturating cystography allows direct visualisation of a dye and its route through the bladder and also does not expose the child to as much radiation compared to CT.
MRI abdomen and pelvis is incorrect because whilst it provides good anatomical information but again is less useful than micturating cystography when visualising a VUR. MRI is also an expensive investigation and requires the child to stay still for a long period. Therefore MRI is not the first line for investigation of reflux nephropathy.
Technetium-labelled renal scan (also known as DMSA scan) is incorrect. This involves the administration of radioactive agents which have a high affinity for the renal cortex and imaging shows good detail of the structures of the kidney. Whilst this nuclear medicine scanning is very useful for identifying renal scarring, it is an expensive investigation and the presence of VUR should be identified first.
