Wouldn't it be easier and far less invasive to give the girl a low-dose contraceptive in a way that would limit her periods to only a few a year? As aceman pointed out, a full hysterectomy isn't without it's consequences. And from what I've read, a lot of doctors are advising against hysterectomies in all but the most extreme cases, where there is no other option (for example, uterine or cervical cancer). I think the mother should look at all other possible options before jumping right to a hysterectomy.
So...she would understand a surgical procedure, with all of the possible side effects and complications? This statement doesn't really make her case."Katie wouldn't understand menstruation at all. She has no comprehension about what will be happening to her body. All she would feel is the discomfort, the stomach cramps and the headaches, the mood swings, the tears, and wonder what is going on."