The mother of a teenage boy who died after neck surgery had been told the operation was "almost zero" risk by medics days before. Cheng Miu-wah, 43, told the inquest into her son's death that she now doubted whether he needed the operation at all, due to conflicting medical opinions. Medwin Cheung Yui-ting, 13, was sent to the intensive care unit after the surgery at Tuen Mun Hospital in August 2011. He died there two weeks later. The inquest into his death opened yesterday, with his mother the first of 16 witnesses to testify in the seven-day hearing. She had taken Cheung for an X-ray scan at Princess Margaret Hospital in January 2011 to test for obstructive sleep apnoea, due to his snoring. The scan showed another problem - two of his neck bones were misaligned. Neurosurgery consultant Dr Po Yin-chung had called it "not much of a problem", but referred Cheung for an MRI at Tuen Mun Hospital, she said. At Tuen Mun on July 8 Dr Wong Sui-to, a neurosurgery medical officer, suggested occipitocervical fusion surgery, as Cheung's neck bone was putting pressure on some nerves. However, about two weeks later another doctor at Princess Margaret Hospital said the problem was "no big deal" in a follow-up consultation. "It seemed strange to me. I was told my son needed an MRI, then surgery, then I'm told he had no problem," said Cheng. Later that day, Cheng and her son consulted Wong again. He said that without the surgery Cheung may become paralysed if involved in a car crash or a similar accident. A month later Cheng agreed to her son's operation. She had consulted three private doctors, but none could tell her whether her son needed the surgery. Three days before the operation on August 1, paediatric neurosurgery professor Dachling Pang, from the University of California, reassured her that the surgery was "almost zero" risk. Cheng agreed to the procedure and Pang and Wong operated on Cheung. She recalled that about 11 hours after her son was taken into the operating ward, Pang came out and told her the surgery had been a success. But three hours later another doctor, who had also been in the operating theatre, said there had been a problem removing a breathing tube, and her son's heartbeat had stopped for some time. The teenager was taken to intensive care where he died. The inquest continues before Coroner Philip Wong Wai-kuen and the jury.