VCUG for 4 Year Old - Sedation?

Hello,
Some background first:  my 10 month old baby has bilateral hydronephrosis (grade 3 on right side, grade 2 on left side) and dodged/delayed surgery by showing some improvement at his last renal scan.  Urologist says he needs to continue to show improvement in next month's ultrasound or he'll again recommend surgery.  We're accustomed to worrying about and getting testing for our baby.

Last weekend our 4 year old was diagnosed with a UTI (urinary tract infection).  He had severe pain during urination, frequent urination, and many accidents.  No fever.  He hasn't had pain for 2 days now, but is still having accidents.  Today our pediatrician recommended an ultrasound and VCUG for our 4 year old.  Per Internet research and our pediatrician, this is standard testing for kids under age 5 after their first UTI.  Plus, with our baby having hydronephrosis, it makes sense to check our 4 year old.

The problem is our 4 year old has high anxiety when it comes to doctors.  For example, at last week's dentist appointment (at a pediatric dentist office), they couldn't clean his teeth because he screamed so loudly.  We were moved to another room because he was upsetting the other children.  We had to hold him down for the dental exam and fluoride treatment and that was traumatic for him and us.  This was his 3rd time to the dentist and the first two times were not that bad; for some reason, he seems to be getting worse.

The ultrasound will be stressful for him but he'll just have to handle it.  At least that's not painful.

I'm worried about the VCUG.  What can we do make the VCUG bearable for him?  As much as I worry about sedation, I feel it is essential for him given his personality.  Can they give him versed (to ease the stress from the IV) and then sedate him during the test?  Any suggestions?  


Help!