Members can only be expelled for disorderly behavior
https://en.m.wikipedia.org/wiki/Gladys_Spellman had a stroke and entered a coma , but got reelected 4 days later. congress called her seat vacant.
She lived four more years.
Btw, Steny Hoyer was her replacement in special election.
She was my representative when I lived in Maryland. I remember that whole incident well. Her husband tried running to replace her but was muscled out by Steny and the Democrat machine.
Lived for nearly 8 years in coma.