eMedicine Specialties > Urology > Hydronephrosis and Ureter Disorders

Vesicoureteral Reflux: Workup

Author: Marc Cendron, MD, Associate Professor of Surgery, Harvard School of Medicine; Consulting Staff, Department of Urological Surgery, Children's Hospital Boston
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Updated: Dec 15, 2008

Workup

Laboratory Studies

• Perform urinalysis and urine culture in all neonates born with antenatal or postnatal hydronephrosis to rule out UTI. More than 90% of newborns void within the first 24 hours.
• The serum creatinine level of a neonate reflects that of maternal creatinine (ie, 1 mg/dL) in the first 24 hours of life; thus, repeat the serum creatinine assessment after at least 24 hours. The average serum creatinine level in a healthy neonate is approximately 0.4 mg/dL.
• Obtain serum electrolytes in neonates with antenatal hydronephrosis due to vesicoureteral reflux (VUR) because they may have dysplastic kidney on the affected side. Check for acidosis.

Imaging Studies

• The recommended radiographic evaluation for VUR includes a VCUG, renal-bladder ultrasonography, and nuclear renal scan (DMSA).
  • Perform VCUG and renal-bladder ultrasonography in any child with documented UTI before age 5 years, any child with pyelonephritis, and any male child with a symptomatic UTI.
  • A renal-bladder ultrasonography may be used to screen older children with UTI. If ultrasonographic findings are abnormal, conduct further workup studies with VCUG to rule out VUR.
  • Suggest that siblings or offspring of index cases with known VUR undergo cystographic screening during the first few months of life, as they are at a 30% risk of VUR.
  • During the initial workup in a patient with suspected reflux, perform the standard VCUG, which provides clear anatomic detail and allows accurate grading of the reflux degree. By filling and emptying the bladder several times (cycling) with the catheter still in the bladder, as described by Lebowitz, the yield of identifying VUR is clearly enhanced. The conventional cystography provides more anatomical accuracy than nuclear cystography; however, nuclear cystography is advantageous (used widely to monitor VUR) because of lower radiation exposure and increased sensitivity. Physicians can also use nuclear cystography to screen family members of a patient with known reflux.
• Voiding cystourethrography/radionuclear cystourethrography
  • Perform the VCUG while the patient is awake and include a voiding phase. Appearance of the urethra is important to determine if the child has some degree of voiding dysfunction or, in males, if the child has posterior urethral valves. VUR is graded based on appearance of contrast in the ureter and upper collecting system during the voiding phase of the cystography. The VCUG also helps to evaluate the bony structures such as the lower spine and the pelvic architecture. It may also show whether the child has excessive feces in the colon.
  • In a neonate or small child, place a pediatric feeding tube rather than a Foley catheter in the urinary bladder. The Foley balloon may lead to a false diagnosis of a ureterocele or evoke an involuntary bladder spasm, complicating the test.
  • After filling the bladder with contrast, remove the feeding tube and allow the child to void.
  • The voiding phase of the cystography is considered the most important part of the test for assessing reflux. Perform the VCUG, rather than nuclear cystography, during the initial evaluation of a patient with suspected reflux; this provides good anatomic information about the lower urinary tract.
  • Allowing the bladder to fill and to empty several times (cycling) increases the sensitivity of the study.
• Renal and bladder ultrasonography
  • Obtain renal ultrasonography to evaluate the presence and degree of hydronephrosis. If hydronephrosis is present, inspect the ureters for dilatation. In a female patient, a dilated ureter in the presence of hydronephrosis usually indicates VUR; however, hydronephrosis in a male infant with an undilated ureter implies ureteropelvic junction obstruction.
  • Evaluate the appearance of the renal parenchyma and size of the kidneys. Abnormal or dysplastic kidneys are smaller and appear brighter or more echogenic. The presence of the corticomedullary junction indicates a normal kidney.
  • Ultrasonography is also a good modality to monitor kidney growth over time.
  • Evaluation of the bladder (prevoid and postvoid, measurement of bladder thickness) provides additional information about the lower urinary tract and bladder function. Bladder ultrasonography helps to reveal bladder-wall thickness, a dilated ureter, and the presence of a ureterocele or ectopic ureter. It also gives information about incomplete bladder emptying due to voiding dysfunction.
  • Compare renal size over time to assess renal growth.
  • Renal ultrasonography has not been demonstrated to be a reliable modality for revealing renal lesions, but obvious renal scarring can be seen in more severe cases.
• Nuclear renal scan
  • DMSA is considered the best nuclear agent for visualizing the cortical tissue, evaluating renal function, and revealing the presence of renal scars. To detect pyelonephritis and renal scarring associated with reflux, use the technetium Tc 99m–labeled DMSA renal scintigraphy. Pyelonephritis impairs renal tubular uptake of a radionuclide isotope, causing cortical photon defects on the DMSA scan. Persistent photopenic defects on the DMSA scan represent renal scarring and irreversible renal damage.
  • The DMSA scan is used to confirm suspected pyelonephritis and to evaluate the effectiveness of VUR medical management. Patterns of abnormal radionuclide may also help to differentiate between renal lesions caused by infections (focal areas of low uptake, usually upper and lower poles of the kidney) from diffuse decreased uptake seen in renal dysplasia due to abnormal renal development.
  • The presence of photopenic areas within the kidney reflects a history of previous pyelonephritis.
  • Development of new photopenic areas within the renal cortex, especially in the polar regions, indicates new scar formation.
  • Diffuse decreased uptake of the radionuclide may indicate renal dysplasia.
  • Recently, several authors have advocated DMSA renal scan as the first study following a febrile UTI. Patients found to have renal lesions on DMSA were found to have a higher incidence of UTIs and VUR, thus preselecting patients who needed to undergo VCUG (top to bottom approach to the evaluation of VUR).
• Follow-up imaging studies
  • Yearly ultrasonography helps to monitor renal growth, to detect hydronephrosis, and to evaluate bladder anatomy and voiding dynamics (filling and emptying).
  • Radionuclide cystography every year to every 18 months helps monitor presence or resolution of VUR and helps to grade the amount of reflux. Compare with earlier studies to determine a trend toward resolution.
  • Obtain nuclear cystography during regular follow-up studies in a patient with known reflux.
  • Although not as anatomically accurate as the standard VCUG, nuclear cystography provides adequate information regarding the current status of VUR.
  • The main advantage of performing nuclear cystography is that it exposes the child to less radiation and may be more sensitive in revealing VUR.
  • Perform DMSA scan if the child develops evidence of pyelonephritis.

Other Tests

• Urodynamics
  • Perform urodynamics in patients with secondary VUR caused by lower urinary tract dysfunction.
  • Lower urinary tract dysfunction, which may cause secondary VUR, includes overactive bladder, spinal cord injury, and bladder outlet obstruction.

Diagnostic Procedures

• Cystoscopy plays a very limited role in VUR diagnosis. Conduct this study when the anatomy of the urethra, bladder, or upper tracts is incompletely defined with radiographic evaluation and when ureterocele is suspected.
  • Perform a video urodynamic evaluation with filling cystometrography and a pressure-flow study with electromyography in any child with a suspected secondary cause of VUR.
  • Filling cystometrography entails filling the bladder with a feeding tube and monitoring bladder pressures during filling and voiding. Normal bladder pressures should be less than 40 cm of water; however, the bladder pressure increases transiently to 60-80 cm of water during voiding.
  • Perform filling cystometrography to evaluate for uninhibited detrusor contractions, bladder compliance, and detrusor leak point pressure, which are significant risk factors for VUR.
  • High detrusor pressure and low urinary flow rate during voiding cystometrography indicates bladder outlet obstruction. This may be due to posterior urethral valves, detrusor sphincter dyssynergia, or Hinman syndrome in children. Bladder outlet obstruction is another secondary cause of VUR.

• Search for CME/CE on This Topic »

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