I would think she should be fine to take a shower. I know I took one immediately when I got home from the hospital after my surgery. I just made sure not to get my incisions directly in the water stream. Usually they tell you before you leave if it's ok or not. I don't know much about the barbie bum but that probably shouldn't get too wet yet. If in doubt, call them and ask.

Inless there is an open wound there is no reason not to wash in the tube or shower as long as she doesn't soak in the tub...Like Marianne said, just don't point the shower head at the suture line...use a mild soap and don't scrub.
She will really enjoy the clean feeling...
Sharon

My mother and I cut holes (head and arms) in a garbage bag and it felt soooo good to wash my hair and the feel of the hot water.

I am also lucky that I have a shower stall with built-in seats and an extendable shower head.

After my wounds started to heal a lot more (no more raging infection), I would just wrap saran wrap around my abdomen.

When my wounds were completely healed, I always took a shower with my colostomy bag removed and washed my stoma and surrounding skin.