Medical

For years, I've used a term to describe a passage in any written text which, for any reason, stops being about sex and is just a list of functioning body parts working and moving in a sea of secretions.

"Medical."

A comment to the previous post lined up a work described as "erotic," but which turned out to be somewhat medical. The protagonist interacted with a dumb, empty environment, just doing a thing endlessly with a thing inside a thing, until she was rescued and POP - out she came. The first word was "In," and the last word "Out."

If you want something in a similar vein, try "How's the Nightlife on Cissalda?" by Harlan Ellison, part of an anthology released in 1990 called "Alien Sex" (ed. Ellen Datlow).