I can understand having different thoughts on the procedure. Perhaps asking DH why he's so against it when it may be the ONLY way to tell if there is an issue because of the IgA issues may help you get to the heart of it and help work through it (if you are thinking you want to do it). My DH HATES hospitals. Really hates them. Not fond of Dr's either. Most times when it is a major decision we have to make walking away for a day or two then coming back together with thoughts and questions he has has been helpful for us.
It's important to remember- This isn't a "diet" that you can go off of. This is a LIFE LONG requirement. Would he rather her not have the information to make that life long decision? Seems easy enough now but what about high school, college and beyond. Do you want to say "oh we thought we were right" or would you prefer to have "proof" to show her? Just some things to think about.
Is a procedure for a kid fun for a parent? Nope. Not even a little. Does it help us make the best decisions we can for our kids at this point in time? It can.