Which of the following statements best describes VCUG?

• A. Ultrasound assessment of the kidneys with urinary bladder filling.
• B. MRI examination of the lower urinary tract during voiding.
• C. CT angiography of the urinary tract.
• D. Voiding cystourethrography, an X-ray study performed during voiding after filling the bladder with contrast.

Answer: (D)

VCUG is a fluoroscopic study that specifically looks at the bladder and urethra during the act of voiding to check for how urine flows and whether reflux occurs.

In this test, the bladder is first filled with a radiopaque contrast via a catheter. X-ray images are then taken as the bladder fills and especially while the patient voids. Seeing the contrast flow upward from the bladder into the ureters or along the urethra helps diagnose vesicoureteral reflux and urethral abnormalities such as posterior urethral valves.

That’s why this option is the best description: it describes an X-ray study performed during voiding after filling the bladder with contrast, precisely what a VCUG is used for. Other imaging modalities listed—ultrasound during bladder filling, MRI during voiding, or CT angiography of the urinary tract—are different techniques that do not define a VCUG.