Toddler urine cath/blood draw: advice?

[rdgove]

DD is experiencing symptoms of Nephrotic Syndrome, which means her kidneys aren't working properly. She was originally diagnosed with allergies, but the Claritin isn't working, the swelling is getting worse, and she has all the symptoms. It breaks my heart for her and makes me feel like an idiot for taking over a week to google her symptoms and make an appt for a 2nd opinion.

She has an appt on Fri first thing in the morning and I'm pretty sure she will need to give a urine sample and have blood drawn. Any advice for helping her to get through both? She may be able to pee for them, but if she can't (and she only pees a couple times a day and usually doesn't pee first thing in the morning) they will need to cath her. I'm dreading it. I had to be cathed once when I was a child and it was a horrible, cringe-inducing experience. I just feel so bad for her.