Can insurance revoke an approval?

My gastric bypass is approved and scheduled for 4/20. Its a revision due to reflux, dismotility, vomiting, etc.

My gastro is having me to a motility and ph study on 4/5. If the results don't come back bad enough could insurance take away my approval?

We have already done endoscopies, biopsies, medication trials, etc. The first time we tried the motility study the probe kept getting tangled in my stomach and could not get positioned correctly.

What do you guys think? Can insurance take my approval away? I am such a worry wart

I suppose it could be revoked but I don't see why it would. It's already been approved, so no additional information is needed. It was approved on the information previously provided.