Conflicts between parents and doctors over the treatment of a child are among the most fraught in medicine. The doctor-patient relationship is based on trust. Once trust is lost, what was seen as care can appear to be an assault.

The mother of the surviving triplet is doing what any parent would: trying to ensure that her daughter receives the best treatment. That means preventing her receiving bad or unnecessary treatment.

The most tragic recent case in which parents disagreed with doctors was over the separation 15 months ago of the conjoined twins known as Jodie and Mary from the Maltese island of Gozo. The operation led, as expected, to the death of Mary but doctors insisted that without it both children would have died. The parents, Michael and Rina Attard, initially objected, forcing St Mary's hospital in Manchester to seek a court order allowing the surgery to go ahead.

Although the Attards now say they are glad the operation went ahead against their wishes, the hospital did not spend long trying to persuade them. It sought the court order five days after the twins were admitted, even though surgery was not needed until more than two months later.

With the baby in Newcastle, who has Goldenhar syndrome, her mother objected to a camera being inserted into her windpipe to prepare for a possible tracheotomy ­ an operation to create an opening in the throat to help her breathe.

The doctors will have been keen to perform the procedure, known as an endoscopy, to familiarise themselves with the anatomy of the girl's throat, which may have abnormalities given her condition, so that should her breathing become obstructed and an emergency tracheotomy be required, they would be ready and prepared to perform it.

Why has the mother objected? It is not clear. Some reports suggested that doctors in Saudi Arabia had already performed the investigation and she did not see why it should be repeated. It is uncomfortable having a rod passed down your throat and there is a small risk of injury.

So her objection seems reasonable. Yet the Royal Victoria Infirmary (RVI) felt it necessary to seek a police protection order to prevent the parents removing the girl. Relations between the hospital and the parents deteriorated over nine days between 22 February, when the girl was admitted, and last Saturday, when the medical authorities applied for the police order. What went wrong?

One clue is provided by a remark the mother made about the care received in hospital. She said: "So many doctors and nurses come in to watch her. She is being used for student purposes. I think the RVI is now a training school and they want my daughter to be an experiment."

Was the mother asked before these doctors and students came to look at her strange baby with half a face? Department of Health guidelines state that patients, or parents, must consent before their cases are used for teaching purposes. At the same time, one can imagine the interest among medical staff in a baby with a condition affecting one in 500,000. See her now ­ this may be the only chance you get in a lifetime.

Although that stems from a healthy medical curiosity, it can leave a parent feeling isolated and her daughter depersonalised, reduced to a specimen. The parent objects as the only way to reassert control.

There is the added complication in this case of coping with the loss of two triplets. Bereavement may have made the mother extra protective and especially anxious. Last week she surprised medical staff by launching an appeal to raise money for the girl's care, despite the fact that all necessary care will be provided on the NHS.

Richard Nicholson, editor of the Bulletin of Medical Ethics, said the rights of parents had to be balanced with the right of the child to receive best treatment. He said: "Provided the doctor takes time to explain, it is usually possible to reach agreement. Doctors do marvellous hi-tech procedures but they neglect development of their people skills."