VCUG test

So my daughter is scheduled for one in 2 weeks after having a uti/fever when she was 4mo (due to covid we had to wait). Now I'm stressing because I don't know what to expect. Reading online doesnt help and the doctors werent really explaining it or maybe I was just not understanding. I don't know. I went back and forth with going through with the test to begin with but ultimately we decided to keep the appointment. Are there any mamas out there who have gone through this with their little one?