• Joan Rivers died age 81 on September 4 at Mount Sinai Hospital in NYC 

  • NY Department of Health and Human Services released damning report into star's cardiac arrest at Yorkville Endoscopy Clinic on August 28

  • Her heartbroken daughter Melissa has hired Manhattan legal powerhouse to launch law suit against doctors and clinic - and is 'outraged' by 'misconduct and mistreatment'

  • Melissa will sue both both Yorkville clinic AND her mom's personal ENT, Dr Gwen Korovin, friends confirm  

Joan Rivers' 'outraged' daughter will sue throat specialist to the stars Dr Gwen Korovin, friends have revealed.

Melissa Rivers is preparing to launch legal action against Yorkville Endoscopy Clinic, which was blasted yesterday in a damning report by the New York Department of Health and Human Services.

And she will not just include the clinic in her legal action - but her mother's personal ENT doctor as well. A source told MailOnline today: 'Melissa is undaunted, she's going after the clinic and the doctors personally involved. These doctors will rue the day they went near Joan.'

The DHH report revealed a catalog of errors at the clinic where the legendary comic suffered a heart attack during a routine throat procedure that led to her death.

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[caption id="attachment_1424" align="aligncenter" width="470"]Joan Rivers Dies After Throat Surgery Complications If you have questions about throat surgery, contact the Colorado Voice Clinic at ColoradoVoiceClinic.com[/caption]

Heartbroken: Melissa Rivers, right, has hired a top NYC law firm to launch legal action against the clinic where her mother Joan suffered cardiac arrest following a routine endoscopy before her death on September 4.

joan-rivers-colorado-voice-clinic-dave-opperman-california-los angeles-vocal-surgeon-specialist-professional-voice-blog-LA-doctors in LA-doctors in Denver-university-of-colorado-ENT-healthone-porter-health-voice-vocal-surgery-healthcare-lawrence-cohen

Joan's doctors: Dr Gwen Korovin (left)  is Joan's private throat specialist, while Dr Lawrence Cohen was the medical director at Yorkville Endoscopy Clinic. Both are believed to have been treating Joan Rivers when she went into cardiac arrest during a routine endoscopy on August 28.

Among the series of blunders, it was reported that staff at the Manhattan clinic failed to weigh Joan before sedating her with Propofol - the anesthetic that killed Michael Jackson.

The clinic also comes under fire for allowing a doctor without privileges, known to be Dr Korovin, to practice at the medical center.

Indeed, Dr Korovin is said to have declared 'I'll go first' as she stepped into the operating room with Dr Cohen, the report says.

It also confirms a picture was taken of the star while she was under anesthesia, alongside Dr Korovin.

Heartbroken Melissa Rivers, 46, will file a multimillion-dollar medical malpractice and wrongful death lawsuit against Yorkville and is working with top firm Gair, Gair, Conason, Steigman, Mackauf, Bloom & Rubinowitz.

'As any of us would be, Ms. Rivers is outraged by the misconduct and mismanagement now shown to have occurred before, during and after the procedure. Moving forward, Ms. Rivers will direct her efforts towards ensuring that what happened to her mother will not occur again with any other patient.'

Meanwhile, the friend said that although grief-stricken, Melissa wants to continue to produce her mother's E! show Fashion Police in memory of Joan. The network is looking to replace the venerable Joan, although the star's close friend Kathy Griffin, who has been linked with the spot, told People: 'They did offer it to me. I don't know if the situation is correct or right at this time for me. We'll see.'

​ Rivers’ official cause of death is “anoxic encephalopathy due to hypoxic arrest during laryngoscopy and upper gastrointestinal endoscopy with propofol sedation.”

The firm needs to obtain Joan's medical records before filing a case in Manhattan Supreme Court and her will also needs to submitted to court and an executor appointed by the judge.

On Monday, the DHH reported that the legendary comic was in excellent health before undergoing what was supposed to be a routine endoscopy.

A look back at Joan Rivers as she talks Fashion Police on set

While the doctors who treated Joan are not mentioned by name, they are believed to be her personal throat specialist Dr Gwen Korovin and Yorkville medical director Dr Lawrence Cohen.

And most worryingly, both Dr Korovin and Dr Cohen failed to notice that Joan's vital signs were going down, as the report claims they failed to provide 'timely intervention'.

According to the findings, Joan, 81, arrived at Yorkville on the morning of August 28 for tests after suffering chronic reflux. She was in good health and her blood pressure was a normal 118 over 80 when her vital signs were first taken at 8.44am. Her pulse was 62 and regular.

The star was set to undergo an EGD (Esophagogastroduodenoscopy), where doctors insert a thin scope and camera into the area between the throat and upper intestine.

However, even though Joan had only agreed to only the ONE procedure, the report states she underwent a Nasolaryngoscopy performed by her personal ENT doctor Gwen Korovin - who was not authorized to practice at the clinic.

This was stopped when Dr Koroway said she did not have a clear view. The EGD then went ahead, carried out by Dr Cohen, and Dr Korovin performed a second Nasolaryngoscopy.

Worryingly, a staff member told the DHH investigators that Joan was NOT weighed before Propofol was administered. This is 'critical' according to the report.

The records note an 'inconsistent' log of the Propofol dosage. Although it says she was given a total of 300 milligrams, the clinic's anestiologist said this was a mistake and only 120 milligrams was administered.

Propofol hit the headlines after the death of superstar Michael Jackson in 2009, when it was revealed he had overdosed on the powerful sedative.

BFFs: Distraught Melissa posted a picture of her son Cooper and her mother Joan, writing: 'Connecticut, 2004. Mom + Cooper = BFFs... A perfect day. #TBT'

BFFs: Distraught Melissa posted a picture of her son Cooper and her mother Joan, writing: 'Connecticut, 2004. Mom + Cooper = BFFs... A perfect day. #TBT'

Still working: Dr Gwen Korovin is still working at her Manhattan office. She charges $460 for an initial consultation and does not accept insurance. She is believed to have been in the room at Yorkville Endoscopy Clinic when Joan Rivers went into cardiac arrest on August 28

Still working: Dr Gwen Korovin is still working at her Manhattan office. She charges $460 for an initial consultation and does not accept insurance. She is believed to have been in the room at Yorkville Endoscopy Clinic when Joan Rivers went into cardiac arrest on August 28

Perhaps the most damning criticism of the clinic comes as the report says 'the physicians in charge of Joan failed to identify deteriorating  vital signs and provide timely intervention during the procedure'.

Indeed, by 9.30am, Joan's blood pressure had plunged to 85 over 49 and no pulse was recorded.

The report, released after interviews with Yorkville staff and others, says there is conflicting information as to the time that Joan was resuscitated and transferred to Mount Sinai Hospital.

Last month, it was revealed that Joan's daughter Melissa Rivers has signed up a Manhattan legal powerhouse and will launch a multimillion-dollar law suit against the endoscopy clinic where the comedienne fell into a coma.

Today, Dr Korovin's lawyer, Michael Kelton, declined to comment.

Dr Korovin is known as the throat specialist to the stars and counts Celine Dion and Ariana Grande as well as a host of Broadway stars among her patients.

Previously, Mr Kelton told MailOnline: 'Gwen S. Korovin, M.D. is a highly experienced, board certified otolaryngologist. She maintains privileges at one of the city's most prestigious hospitals. She is respected and admired by her peers in the medical community and she is revered by her patients.

Famous clientele: Dr Gwen Korovin, who is believed to have been in the room when Joan Rivers underwent her ill-fated procedure, counts Celine Dion as one of her patients. In the singer's 2010 documentary, Dr Korovin performs a laryngoscopy on the star and they talk about her resting her vocal chords

Joan Rivers throat specialist in Celine Dion documentary

'As a matter of personal and professional policy, Dr. Korovin does not publicly discuss her patients or their care and treatment. Further, Dr. Korovin is prohibited by state and federal confidentiality laws from discussing her care and treatment of any particular patient.

'For these reasons, neither Dr. Korovin nor her attorneys will have any public comment on recent press reports regarding her practice. We ask that the press please respect Dr. Korovin's personal and professional policy of not discussing her patients, as well as the privacy of her patients.'