A meeting of up to 400 parents who believe their children's hearts were kept without their knowledge by Alder Hey Children's Hospital, in Liverpool, has been called for next week.
They are calling for a public inquiry into the way up to 2,000 hearts and other organs were collected at the hospital over the past two decades.
Solicitor Ian Cohen said that in many cases pathologists removed and kept every single organ from children's bodies. 'I have clients who have been told that the child they buried is nothing but a shell. All the organs have been retained.'
The practice of organ retention, and the organ collection at Alder Hey, came to public prominence as a result of the Bristol Royal Infirmary inquiry.
It heard that at least 15,000 children's and adults' hearts have been kept by nine English hospitals. University Hospital of Wales in Cardiff has also admitted keeping babies' hearts.
The subsequent outcry has sparked three separate national investigations, as well as an internal inquiry at Alder Hey.
Parents have attacked the wording of post-mortem consent forms that refer to 'tissues' without spelling out which body parts will be removed or that they will not be returned before burial.
And the Bristol Royal Infirmary inquiry has come under pressure from the Bristol Children's Heart Action Group to recall four managers to give further evidence about organ retention.
They claim the trust gave families the impression that organs were 'retained whole and in one place', while in fact in' one case the heart was not in one piece but in 41 pieces, and in another, not in one piece but 53 pieces'.
These pieces are on slides which cannot be returned 'because they form part of the medical records'.
A Department of Health spokesperson said the remit for an inquiry into organ retention by chief medical officer Professor Liam Donaldson is still being decided.
But health secretary Alan Milburn 'is keen to find out what parents think they are signing up to when they sign a post mortem form and whether it is clear what that means'.
The Medical Research Council has issued proposed guidelines for obtaining specimens to use in research, and the Royal College of Pathologists is drawing up its own recommendations on consent to remove organs during autopsies.
RCP registrar Dr Julie Crow said the guidelines would be 'more specific' about defining organs 'and getting more upfront consent' to keep them.
But she warned that organs such as the brain had to be fixed in formalin for several weeks before they could be examined.
'If that is to go by the board because of public concern we might not be able to establish the cause of death, ' she said.
Therese Harvey, the human resources director at the Royal Liverpool Children's trust, which runs Alder Hey, said it had set up a helpline for parents and was employing counsellors to help them discuss whether to retrieve the organs for burial or cremation.