I asked TSA this morning. As someone who works in Home Healthcare and Rehabilitation, I should have known this when I first read it. As a reader of FT, my mind was in the gutter

There are people who need to catheterize themselves on an ongoing basis.
Sterile lubricant (not warming gel) is used. Most "Self Caths" are pre lubricated, but still need extra lube sometime.

Also used with ostomy patients.