Starship specialists have described an appointment with the parents of a baby at the centre of a court dispute that was hijacked by one of their support people spouting conspiracy theories.

The High Court has taken guardianship of the baby to allow him to have the life-saving heart operation he needs.

It was delayed by his parents' insistence he only be given blood from someone who has not been vaccinated against Covid-19.

The judgement issued by Justice Gault last night outlined how doctors tried to work with the parents but the relationship eventually broke down.

He referenced a meeting on November 25 between Starship Hospital's paediatric cardiac surgeon in chief and other specialists.

"Dr [Kirsten] Finucane said this meeting was hijacked by the parents' support person who proceeded to pressurise the specialists with her theory about conspiracies in New Zealand and even said that deaths in infants getting transfusions were occurring in Starship Hospital," Justice Gault said in the judgement.

After several minutes the specialists asked to leave the meeting and walked out with the support person continuing to try to talk to them.

That meant they were unable to explain their position to the parents.

The judgement described how, in October, the baby's parents were distressed when they learned he had been given a blood top-up during surgery and said in future they wanted to find an alternative.

The doctors asked the Blood Service if the parents could use a donor of their choosing but it was not practical because so many different blood products were likely to be needed.

In the end the specialists felt they could no longer wait because the baby was getting sicker and at greater risk of complication, the judgement said.

Justice Gault's decision gave Starship doctors the right to carry out the surgical and recovery care the baby needed because that was in the baby's best interest, he said.

His parents remain responsible for all his other care.

He outlined some of the evidence provided by the family's lawyer, Sue Grey, but noted that much of it did not come from clinicians.

She had felt the parents were being dismissed as conspiracy theorists and their concerns were being ignored.

Justice Gault noted the relationship between doctors and the parents had suffered and urged both sides to work together.

The loving parents wanted the best for their child, he said.

He accepted they had genuine concerns about the risk of using blood from vaccinated donors.

However, he agreed with advice from doctors that it was safe.

Using blood from a donor of their choosing was not an available alternative, nor supported by doctors so was not a safe alternative in the baby's interests, he said.

"For these reasons, and given that Baby W needs urgent surgery, an order enabling the surgery to proceed using NZ Blood Service blood products without further delay is in Baby W's best interests."

-Rowan Quinn/RNZ.