The New York out-patient clinic where the late Joan Rivers suffered cardiac arrest did not follow all the standard protocols during the throat procedures it conducted on her, according to a government agency report.
Rivers died on September 4 at the age of 81 in a New York hospital a week after her heart stopped during the procedure at the Yorkville Endoscopy Centre.
The Centres for Medicare & Medicare Services (CMS), the agency that released the report, said there was no record that staff at the centre weighed the comedian before administering the sedative Propofol on August 28 and there were inconsistencies recorded in the dosage of the drug.
It also said there were no records of consent for all the procedures performed. The report added that a doctor was in the operating room without authorisation and said physicians failed to detect Ms Rivers' deteriorating vital signs.
Melissa Rivers, the comedian's only child, said in a statement that she is "outraged by the misconduct and mismanagement" that occurred and will ensure it does not happen again with any other patient.
Her lawyers are investigating the circumstances surrounding her mother's death.
The CMS released the report following an investigation by the New York State Department of Health, which questioned doctors and staff and examined records.
"The Centres for Medicare & Medicaid Services does not comment on information contained in a facility's statement of deficiencies," it said.
The New York Chief Medical Examiner's Office said Rivers died of a predictable complication during a medical procedure and lack of oxygen to the brain.