scene suggestion

Petite teen (like Pipper Perri petite) is studying nursing, the semester was on enmas.

Their teacher believes that understanding comes from experience not theory so has organised a doctor to administer an actual enema.

He has the girl remove ll her clothes, with a measures tape he measures around her belly

He has her bend over the exam table

He administers what is a massive iv bag enema (she can barely take it)

Standing up straight he re-measures her belly 

he hands her a gown and she puts it on and he tells her she can go and evacuate her bowls now

She heads to the restroom, the restroom is at the end of the corridor on the other side of the 'full' waiting room

As she heads to the facilities the enema liquid spurts out a few times, but halfway through the waiting room the entire thing just starts gushing.  Squatting down in the middle of the room shocked bystanders giggle, stare or turn away but honestly she's just relieved