Was told yesterday that having a positive tests for soy means not having a minor op in the day care unit but in the main hospital so full back up is available. Apparently they may have wanted this for nut allergy anyway (because of a risk of cross reaction between soy and peanut). They will presumably use a different anaesthetic anyway.
We will be taking our own snack for after the op to ensure there is something they can safely eat before coming home.