The mum of a 14-year-old girl who died at world famous Great Ormond Street Hospital (GOSH) after spinal surgery has told an inquest her death was a result of poor planning.

Amy Allan was recovering after surgery to correct curvature of her spine when she died in September 2018.

The youngster, from Dalry in Scotland, was taken off a ventilator the day of her operation but died 23 days later.

She was removed from the ventilator at 11.20pm but did not receive ECMO, where blood is oxygenated outside the body, until 8am the following morning.

Edward Ramsay, counsel for the family, asked Amy's mum Leigh: "Why do you feel, given you were there, that Amy died on September 28?"

She replied: "I think the reason is lack of planning, lack of communication, and lack of ECMO being available straight away."

The teen was diagnosed with Noonan's Syndrome, a genetic condition effecting her heart and lungs.

She also suffered from hypertrophic cardiomyopathy - an unhealthy thickening of her heart muscle, and pulmonary hypertension, both of which increased he risk of cardiac arrest from being on a ventilator after surgery.

Dr Aravinci Swaminathan, the man who removed the ventilation tube, said: "I was aware of the risk involved with her extubation given her complex cardiac background.

"I had anticipated the possibility of hypertension and heart failure.

"Early extubation would ease the stress on her right heart."

Despite the rapid deterioration in her condition which happened after she was taken off the ventilator, a pathologist examination did not connect the event with her death 23 days later.

Earlier in the hearing, Steven Playfor, an independent doctor called by her family to give evidence at her inquest, at St Pancras Coroners Court in London, said: "It (taking her off the ventilator) certainly materially contributed [to her death.]

But when asked today about lasting damage from the extubation, Pathologist Dr Liina (corr) Palm said: "There was no irreversible damage to either organ [the heart or brain]."

The hearing, which has so far lasted for three days, has also looked into the hospital's provision of ECMO - an emergency life-support technique.

The fact that ECMO, was available at GOSH was the reason Amy had her operation there.

Yesterday (TUESDAY), the court heard that an ECMO specialist, Dr Rahit Saxena, had not been told Amy was due the treatment.

Mr Ramsay asked him: "Given all the evidence about how difficult it is to assemble the [ECMO] team at 4am then why hadn't you been alerted that this might need to happen.

"It stands to reason that doing this in the middle of the night was the worst time do do it."

Dr Saxena said: "Yes, we have an expectation that if someone has been listed for ECMO support I should know about it. No-one informed me."

The conclusion of the inquest, which will officially establish how Amy died, is due to be heard tomorrow.