Joan Rivers died on September 4, 2014, due to brain damage caused by a lack of oxygen during a medical procedure. She was undergoing a minor outpatient procedure—a laryngoscopy and an upper gastrointestinal endoscopy—at Yorkville Endoscopy in Manhattan to examine her vocal cords and treat voice changes and acid reflux. During the procedure, she suffered cardiac arrest caused by hypoxic arrest (lack of oxygen to the brain), which led to anoxic encephalopathy (brain damage due to oxygen deprivation)

. She was sedated with the anesthetic propofol at the time, which is known to have rare but serious side effects such as hypoxia and cardiac arrest. After losing oxygen, she was taken to Mount Sinai Hospital, placed on life support, and never regained consciousness before passing away surrounded by family and close friends

. The New York City Medical Examiner classified her death as a "therapeutic complication," meaning it was a known risk of the procedure rather than due to negligence, although later investigations and a malpractice lawsuit alleged medical errors during the procedure and care

. The official cause of death was listed as brain damage from lack of oxygen during the medical exam