They are looking for vesicoureteral reflux. This is a disease where the urine refluxes back up the ureters into the kidneys. Every young child with a UTI should be evaluated for this, since this can lead to kidney scarring and damage. The VCUG would be the appropriate test to evaluate for this.
Typically, any child under the age of 7 should undergo a VCUG to ensure that reflux isn't present. From your story, it would seem that the course of action is appropriate.
Followup with your personal physician is essential.
This answer is not intended as and does not substitute for medical advice - the information presented is for patient education only. Please see your personal physician for further evaluation of your individual case.
Kevin, M.D.
Medical Weblog:
kevinmd_b