The drama unfolded near Leeds this morning, when the woman was a passenger in a car driven by her son.
Caught in standing traffic as snow caused chaos on the roads, she decided to leave the vehicle to relieve herself near the hard shoulder.
But she was horrified when the cars began to move again while she was still outside. Her son was forced to drive away to avoid blocking the carriageway.
Luckily a police patrol vehicle was passing and she managed to flag down the officers, who included Sgt Paul Cording, who Tweeted about the amusing incident.
The police drove her to Wetherby Services, where her son was waiting for her.