It's not clear why Appanna was banned from operating on his patients at Anglesea Hospital on March 30 last year but his spokeswoman Glenda Hughes said a case involving the doctor was reported to the Health and Disability Commissioner the same month "which has not yet been resolved".
"All doctors may be investigated by the HDC from time to time. Currently the HDC have found no issues with Dr Appanna."
The Health and Disability Commission would not confirm if a complaint had been taken against the doctor but the Herald understands there was an incident that preceded the suspension.
Appanna is suing Anglesea Hospital for lost income in a civil case he launched through the High Court at Auckland last year.
Anglesea Hospital chief executive Nicky van Praagh said she could not discuss individual doctor credentialling processes but that Appanna "is under an ongoing process".
A judgement in the case, obtained by the Herald, noted the hospital was ordered by the court to reinstate the privileges in October last year pending further court action.
At a hearing last month, Appanna's lawyers said the hospital had failed to comply with the injunction order by not providing appropriate nursing support to allow him to operate at the hospital.
He is claiming damages for harm to his reputation, compensation for pecuniary loss and general damages of $25,000, and said the suspension was "wrongful".
At the September 15 hearing, in front of Justice Geoffrey Venning, Anglesea Hospital argued for Appanna to release the names of his patients to prove they were "real" so that the value of damages sought for lost income could be quantified.
However Justice Venning agreed with Appanna's lawyers that lost income could be worked out on previous years' receipts to protect the privacy of patients.
He ordered Appanna to provide details of lost income and harm to his reputation by November 6.
Southern Cross Hospitals chief executive Terry Moore said Appanna had not operated at Southern Cross Hospital in Hamilton since December 2015, but he could not say why.
The Medical Council said it did not have any conditions on Appanna's scope of practice and it could not confirm complaints made about doctors.
Appanna made headlines last month when it was revealed he moonlights as an R18 events organiser, including co-organising the NZ Fetish Ball in Auckland and Christchurch. The Auckland event is scheduled to be held tonight.
Appanna said on his blog he has never hidden his "numerous business interests" outside of his work as a gynaecologist.
These include running the Risque Events ticketing site and Cirlesque show - a burlesque come circus "extravaganza" which the Herald understands includes nudity.
He is also in partnership with Venus Starr for the Dark Starr Inked Models pageants, Wild Storm Male Strip Revue and Starr Strippers, a website for hiring strippers, according to the blog.
Appanna and his wife Sandie co-run the Fetish Ball with business partner Glen Rossiter and have been involved in the adult-only events industry for almost a decade.
"I have never hidden the fact we run these various companies. I have however not deemed it necessary for my patients to be aware of this," Appanna wrote on the blog, dated August 30, 2017.
"It has no bearing on their management or their care. However many patients in the alternative lifestyles do choose to see me as they know that they will not be judged because of the lifestyle choices they have made."
He said he did not see it as an issue that some of the adult companies were registered to the same address where he works as a gynaecologist, The Women's Health Centre at 83B Tristram St.
Hughes said Appanna's involvement in the R18 events was minimal and had been restricted to administrative tasks.
"This business is situated and run completely independently of his medical practice."
But on phoning Women's Health an automated message gives callers the option to select Cirlesque.
