A 2006 randomized trial in the BMJ lines up with that. Dean Seehusen and his team at Eisenhower Army Medical Center split 197 women into two groups, one with feet in metal stirrups and one with feet resting on the corners of the exam table.

Without stirrups, reported physical discomfort dropped from 30.4 to 17.2 on a 100-point scale, and the sense of vulnerability fell from 23.6 to 13.1, roughly 43% and 44% lower.

The quality of the Pap smears didn't differ significantly. As the authors put itiOnce a woman's feet are placed in stirrups, getting out is neither quick nor easy."

Study link: https://pmc.ncbi.nlm.nih.gov/articles/PMC1513491/