Apparently this is NOT about blood. The brain surgery was preformed a while back. The dispute is about getting the child the less invasive Proton beam therapy.
http://www.theguardian.com/society/2014/aug/31/ashya-king-what-is-proton-beam-therapy
Proton beam therapy is a form of radiotherapy designed, like all the others, to kill cancer cells. The difference between this and conventional forms of radiotherapy is that it is thought to cause less damage to the healthy tissue around the tumour – and for that reason is particularly suited to children, who are more susceptible to harm from radiation because they are still growing. It is possible for large doses of radiation to cause secondary cancers in the long term..................
..........
Protons, which are positively-charged particles in the centre of any atom, cannot travel as far as x-rays. They stop when they reach the tumour. There should be less collateral damage, leading to fewer side-effects in the long term. But although that is the theory, and a number of countries have invested in hugely expensive machines on the strength of it (and the UK is now building two of them), there are still some questions over the efficacy and side-effects.
Proton beam therapy is not the best treatment for every patient – in fact, it is said to be suitable only for about 1% of all cancer patients. For some years, the NHS has paid for children who are thought to be likely to benefit to travel to the US or Switzerland for this kind of radiotherapy, at very high cost – the NHS pays for travel and accommodation for the child and a family member, as well as for the treatment.