Joan Rivers' daughter Melissa is apparently planning to file a lawsuit over the death of her mother.

The heartbroken TV personality has hired a top Manhattan law firm to investigate after the comedienne died in September, a few days after she went into cardiac arrest during a throat procedure at a doctor's office.

Several sources have said that Melissa is planning to file a multi-million dollar wrongful death lawsuit against the endoscopy clinic in New York and the doctors involved in carrying out the procedure.

E! News reported that she has hired law firm Gair, Gair, Conason, Steigman, Mackauf, Bloom And Rubinowitz.

Partner Ben Rubinowitz said: "In order to fully determine all of the facts and circumstances surrounding the death of Joan Rivers, we confirm that our firm has been engaged by Melissa Rivers and her family."

Earlier this month the medical examiner's office ruled that the late Fashion Police host died from low blood oxygen during a routine medical procedure to check out voice changes and reflux.

Joan, who was 81, died on September 4 after she'd been in hospital since the procedure on August 28.

She died from "anoxic encephalopathy due to hypoxic arrest" - brain damage due to lack of oxygen - during a procedure to scope her upper gastrointestinal tract and vocal folds, a spokeswoman for the city's medical examiner said.

The death was classified as a complication of a medical procedure.