The New York City medical examiner says Joan Rivers died from low blood oxygen during a medical procedure.
The comedian, who was 81, died Sept. 4. She had been hospitalized since Aug. 28 when she went into cardiac arrest during a routine medical procedure at a doctor's office to check out voice changes and reflux.
Medical examiner spokeswoman Julie Bolcer said Thursday that the cause was brain damage due to lack of oxygen. It is classified as a therapeutic complication, meaning that the death resulted from a predictable complication of surgery.
The New York state health department is investigating the circumstances.
Her daughter Melissa Rivers said in a statement that the family continues to be saddened by the tragic loss.