Joan Rivers Death Lawsuit: Doctor Performed Unauthorized Throat Biopsy, 'A Huge No-No' [VIDEO]

More details are emerging about the sudden death of comedienne Joan Rivers.

Kelly Osbourne Hospitalized After Losing Co-Host, Joan Rivers

Rivers arrived at Yorkville Endoscopy in New York City on Aug. 28 for a routine procedure turned wrong.

New York Daily News reports that the television personality underwent an unplanned throat biopsy, which ultimately led to her fatal hospitalization.

Joan Rivers Stopped Breathing During Throat Surgery

Friends told NYDN that Rivers' visited Yorkville Endoscopy for "a diagnostic produced [to] see why her voice had gotten raspy," which is typically performed in a hospital setting.

Rivers brought her own doctor along, an ear, nose and throat specialist, who performed the procedure.

When the doctor from Yorkville Endoscopy found "something" in the star's vocal cords, Rivers' doctor reportedly "asked if he could use their instruments to perform an unplanned throat biopsy," said NYDN.

"He asked and they let him," a source said to the paper. "A huge no-no."

Reports claim Rivers agreed to the endoscopy, but not a biopsy.

During the unplanned surgery, Rivers suffered a vocal cord contraction medically referred to as "laryngospasm," which cut off her air supply and stopped her from breathing.

Sources said if the biopsy had been done in a hospital, "she might have been okay." Hospitals are better equipped for unexpected outcomes and spur-of-the-moment surgeries.

Rivers' daughter, Melissa, and Yorkville Endoscopy have made no comment about the recent report, claimed NYDN. The initial autopsy performed on the Fashion Police host came out inconclusive, failing to find the "cause and manner of death," the paper reported.

Stay tuned for more Joan Rivers news.