What is a Voiding Cystourethrogram (VCUG)?

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Dainyal Siddiqui, MD

Internal Medicine

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Manuel Jimenez, MD

Cardiology

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Franz Pierre-Louis, MD

Infectious Disease

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Last updated: March 8, 2025 • View editorial policy

From the Guidelines

A voiding cystourethrogram (VCUG) is a diagnostic imaging procedure that evaluates the bladder and urethra during urination, primarily used to detect vesicoureteral reflux, urethral abnormalities, or bladder dysfunction, as recommended by the most recent guidelines 1.

Definition and Purpose

A VCUG involves filling the bladder with a contrast dye through a catheter, then taking X-ray images while the patient urinates to observe how the bladder and urethra function.

  • The test is commonly performed in children with recurrent urinary tract infections or suspected urinary tract abnormalities, though adults may undergo the procedure as well.
  • The procedure typically takes about 30 minutes and may cause temporary discomfort from catheter insertion.
  • Patients should expect to urinate during the procedure while X-ray images are captured.

Diagnostic Evaluation

The diagnostic work-up for VCUG should evaluate the overall health and development of the child, including the presence of febrile UTI, renal status, and bladder and bowel function, as outlined in the European Association of Urology/European Society of Paediatric Urology guidelines 1.

  • Standard imaging tests include renal and bladder US, voiding cystourethrography (VCUG), and nuclear renal scans.
  • VCUG is the standard modality for diagnosis of VUR, especially for initial work-up, and allows for classification of VUR into five grades.

Safety and Precautions

The procedure is generally safe but does involve exposure to a small amount of radiation, as noted in the literature 1.

  • Alternative imaging modalities, such as contrast-enhanced voiding urosonography (ceVUS), magnetic resonance VCUG, and nuclear cystography, are available but conventional VCUG remains the gold standard due to its ability to determine the grade of VUR.
  • After the test, drinking extra fluids helps flush out the contrast dye, and some patients may experience pink-tinged urine or mild burning during urination for a day or two, which is normal.

From the Research

Definition and Purpose of Voiding Cystourethrogram (VCUG)

  • A Voiding Cystourethrogram (VCUG) is a fluoroscopic technique that images the urethra and bladder during both bladder filling and emptying, as well as the ureters and kidneys when vesicoureteral reflux (VUR) is present 2, 3.
  • The purpose of VCUG is to assess the urinary tract, including the urethra, bladder, and ureters, and to diagnose conditions such as VUR 3.
  • VCUG is considered the gold standard test for diagnosing VUR, along with contrast-enhanced voiding urosonography (VUS) 3.

Procedure and Technique

  • The VCUG procedure involves filling the bladder with a contrast agent and then emptying it, while taking images with a fluoroscope 2, 4.
  • The American Academy of Pediatrics Sections on Urology and Radiology published a joint standardized VCUG protocol in 2016, which recommends at least 2 voiding cycles to identify intermittent VUR and/or ureteral ectopia 2, 4.
  • The protocol also recommends including various data points, such as scout image reporting, cyclic studies, and measured post-void residual (PVR) 5.

Indications and Applications

  • VCUG is commonly used to diagnose and manage VUR, as well as to assess the anatomy and function of the lower genitourinary tract in suspected anatomical malformations 3.
  • VCUG is also used as a follow-up examination after urinary tract surgery 3.
  • The test is typically performed on children, especially those between 2 and 24 months of age with urinary tract infections 4.

Reliability and Limitations

  • The reliability of VCUG for grading VUR has been questioned, with studies showing that there can be disagreement between raters, especially for grades II-IV 6.
  • Despite this, VCUG is considered a reliable test for grading VUR, with strong inter-rater agreement and high kappa values 6.
  • However, the test may have limitations, such as radiation exposure and the need for standardized protocols to ensure consistent results 2, 5.

References

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Professional Medical Disclaimer

This information is intended for healthcare professionals. Any medical decision-making should rely on clinical judgment and independently verified information. The content provided herein does not replace professional discretion and should be considered supplementary to established clinical guidelines. Healthcare providers should verify all information against primary literature and current practice standards before application in patient care. Dr.Oracle assumes no liability for clinical decisions based on this content.

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