The complication resulted in a loss of oxygen that led to brain damage, the examiner concluded after an investigation into her death on September 4 at the age of 81.
The medical examiner said the star had been sedated with propofol. An overdose of the same anesthetic, administered by his doctor, caused the death of Michael Jackson in June 2009.
The examiner’s office also revealed that Rivers had been admitted to a clinic for procedures to evaluate changes in her voice and a digestive disorder.
“The cause of Ms Rivers’ death is anoxic encephalopathy due to hypoxic arrest during laryngoscopy and upper gastrointestinal endoscopy with propofol sedation for evaluation of voice changes and gastroesophageal reflux disease,” it said in a statement.
“The death resulted from a predictable complication of medical therapy,” it added.
Rivers died a week after she stopped breathing during the procedure at the Yorkville Endoscopy Center.
The New York State Health Department launched an investigation into the circumstances that surrounded her death.
Rivers, a trailblazer at a time when comedy was all but off-limits to women, enjoyed a phenomenally successful career that lasted right up until her death. (AFP)