According to The New York City Office of Chief Medical Examiner's (OCME) investigation, the cause of Rivers' death was anoxic encephalopathy (brain damage) due to hypoxic arrest (a decrease in oxygen to the brain) during surgery -- a laryngoscopy and upper gastrointestinal endoscopy.
The report also revealed that Rivers was under propofol sedation during the procedure. Michael Jackson died from a fatal dose of propofol in 2009.
Rivers' death was classified as a "therapeutic complication," which means that the death officially resulted from a predictable complication of medical therapy.
The legendary comedienne underwent a routine endoscopy in August to evaluate changes in her voice and to deal with acid reflux. She was placed in a medically induced coma after going into cardiac arrest and passed away a week later. She was 81.
Following her death there was an outpouring of love from her peers in Hollywood.
"What a sad ending to a brilliant and tragi-comic life," said Bette Midler. "One of the bravest and funniest of all."
"Joan Rivers was a dear and wonderful friend who I've known for 45 years," said Larry King. "Great guest, pal, comedian and mother. We will never see her likes again."
Daughter Melissa Rivers, 46, reacted to the autopsy, giving the following statement: "We continue to be saddened by our tragic loss and grateful for the enormous outpouring of love and support from around the world. We have no further comment at this time."