I am feeling at a loss for how to approach a discussion of bowel problems with my mother. Suggestions?

Candy was constipating for my mother. Also you have to be wary of UTIs as they get older and don't wipe as well or wear liners/pads, so might want to incorporate some cranberry juice.

An update - first, I was not clear in my original post, that these events happen about 2x/month. As she lives alone (with 3x/day visits from my sister or me or her visiting CG who showers her weekly) and nobody keeps notes, I have no way to quantify the events/details.
Before MD visit, I spoke to her about the issue of constipation - she insists not a problem, though it has been for much of her life. She reminded me she is a nurse and would know if she had a problem!!
Then raised the reality about people putting on gloves to manually remove waste and paper from the toilet - she was very embarrassed, of course. Even when her CG who was present confirmed this issue, she refused to believe it. I asked if it is ok for people who care about her to have to do this task - she agreed that it is ok. I know she doesn't really understand. Then she started to cry, and went over to her CG for a hug and reassurance.
The plan for now is prune juice in the morning. Will see if the CG can get her to drink it - found out that she eats and drinks MUCH more for CG than she does for either of her daughters.
I know it is up to my sister and I to ensure her health and safety as much as we can, within limits of her wishes.
After waiting 90 minutes to see her MD (very unusual, apparently) I omitted this issue from the visit - other topics more important. Lacking UTIs or a trip to ER for disimpaction, I don't think I have enough data to make this a priority.
Thanks to all for their suggestions. Will keep in mind as we go along.