Any tips for pumping while traveling and not really having a fridge or freezer to store the milk? My…

Any tips for pumping while traveling and not really having a fridge or freezer to store the milk? My daughter will be staying with my parents for three days this week while we take our son to see his specialist out of town. We will be at my Grandmas before and after the appt, but the day of we will be at the hospital all day so does anyone have any ideas of how I could save that milk? Or am I just gonna have to throw it out? 😩