It seems like the world may never know what killed Joan Rivers, because of the decision to not perform an autopsy. This is all due to Melissa Rivers, according the the NYC Medical Examiner, who ordered that an autopsy not be performed.
Of course doctors, honored the daughter’s wishes, however, we run into a small issue. Without an autopsy it’s basically impossible to pinpoint the exact cause of death. So even thought the Medical Examiner predicted an issue with the procedure that lead to lack of oxygen (and irreversible brain damage), an autopsy can show the precise issue (for example, according to one source, a puncture in the throat).
The Rivers family may never get a real answer unless a doctor or nurse admits to making a mistake. Until then, the death of Joan Rivers will be another mystery that has yet to be solved.