Cash for kidneys from live donors and a legal presumption that a dead person's organs are available for transplant are two of the radical ideas being proposed to address a chronic shortfall of voluntary organ donors.

According to UK Transplant, the organisation that matches recipients and donors, 90% of the population favours organ donation but only 25% gets round to signing up with the NHS Organ Donor Register. Consequently, someone dies every day while waiting for an organ transplant. With only 50 organ transplant operations carried out in Scotland last year and over 700 people on the waiting list, the situation is now at crisis point. UK-wide, 7234 people are awaiting a transplant.

The announcement last week that a couple in England had paired with a Lothian couple in a kidney swap' could pave the way for further such arrangements. If so an additional 200 people a year could potentially benefit. But it isn't enough, and other options are still needed.

Sue Roff, a senior research fellow at Dundee University Medical School, advocates paying live kidney donors while, last month, the British Medical Association backed "presumed consent", which would mean medical staff could assume that any deceased person's organs or tissue are available unless they had officially opted-out before their death.

While Roff's idea is untried, the BMA's proposals have the political backing of Health Secretary Alan Johnson and his Scottish counterpart Nicola Sturgeon, who have both given the go-ahead for a UK-wide investigation into presumed consent by the Organ Donation Task Force.

Yet opinions remain divided. While England's Chief Medical Officer Liam Donaldson is a supporter of the proposal, his Scottish counterpart, Harry Burns, is sceptical, saying: "Public support for presumed consent is not in evidence. Therefore I do not believe we can change our position at this stage."

Despite the polls, many feel Burns is correct in his reading of a public that has yet to be fully informed on organ donation.

The ethics of when exactly a person is deemed "irreversibly dead", the legal presumption that their organs will be harvested if they have not actively registered their objections and the emotional burden for the family who may want to supersede the deceased's wishes - all have yet to be argued and put into a legal framework.

According to BMA spokesperson Sally Winning, an informed public consultation is exactly what the BMA wants. The association's position is based on a simple problem. She says: "Every day, perfectly healthy organs are cremated and buried. It is not until someone in a family requires an organ that everyone else registers. That is why we would like people to start talking about what they want before the situation of ill health or family bereavement arises."

While the BMA believes that presumed consent is the right way to improve donation rates, Joyce Robins disagrees. The co-director of watchdog group Patient Concern believes that not enough has been done to entice people to register. She says, "I have never once in a lifetime spent in GP surgeries, blood donor sessions and hospital visits been asked if I would sign up. That is an opportunity wasted ridiculously."

She disputes surveys that report 90% of people support organ donation. "Surveys may show a large majority willing to donate organs but giving the, feel-good answer in the street is very different from facing the reality of the process."

Christine Philips encountered just that brutal reality when her 18 year-old daughter, Josie, died in a fire due to smoke inhalation in 2004. Minutes after Josie's ventilator had been turned off, Christine was approached by the hospital's donor transplant co-ordinator. Philips recalls: "Obviously you are in a state of shock and don't think you can make any decisions, but the donor people were very sensitive. They said that even in years to come Josie would still be helping so many people. It was so, so hard though."

Only later did it emerge that Josie had already registered her wish to be an organ donor. That fact still comforts her mother, who says: "I would have been broken hearted if I had said no."

Josie's organs helped a man who had endured 13 years of kidney dialysis; a woman received the other kidney and pancreas, another patient received Josie's liver and a teenage boy was given her heart valve.

Another beneficiary of a registered organ donation is 42-year-old systems analyst Sheila Bell. Having received a kidney transplant two and a half years ago, after a decade-long wait, life for Sheila, from Lanarkshire, no longer revolves around kidney dialysis sessions four times a week.

A registered organ donor since the age of seven, Sheila is a fervent supporter of presumed consent. She says: "Humans can be pretty apathetic so if this became law it would make people talk about the issue. If they did feel strongly for personal, religious or squeamish reasons then they'd just opt-out." She also favours the "hard" opt-out option, under which a deceased person's wishes would over-ride those of their family. In contrast, the BMA's proposed "soft" system would take into account the views of relatives.

Like many health professionals, senior research fellow at Dundee University Medical School Sue Roff wants a full and explicit public education programme on organ donation. Controversially, that includes a proposal that live kidney donors should be eligible for financial remuneration. She explains: "I am very conservative on the retrieval of organ parts from the dead and the dying and very liberal on the issue of live donation."

She emphasises the distinction between two types of death - brain and cardiac. Despite the fact that organs retrieved from a brain-dead person are better for transplant because the heart is still pumping blood around the body, the statistics show a two-year decline in organ donations from people who suffered brain-death.

She attributes this to public "acceptance" of cardiac death, when the heart stops, but scepticism about brain death.

She explains: "Families are very reluctant to donate organs when the brain is declared dead but their loved one's heart is still pumping blood. The body still looks pink and healthy therefore you wouldn't want to bury or cremate it." Her radical idea for live kidney donors relieves the family of involvement altogether. With demand at an all-time high due to an upsurge in diabetes and the recent surgical trend of pre-emptive kidney transplants (which means the average patient requires three kidneys in a lifetime), her idea could cut waiting lists.

By establishing a tightly controlled and properly regulated model, body parts could be ascribed a value - in the case of a kidney she suggests a figure of £28,000, approximately equivalent to the average annual salary in the UK.

The scheme could, it is hoped, avoid "transplant tourism", where people travel to China and India for a new kidney only to return to the UK seeking after-care. Any squeamishness says Roff, could be tempered by society's existing acceptance of egg donation to infertile couples and "the entire operation being on a par with a caesarean in terms of surgical complexity, risk and scarring."

She argues: "We already encourage kidney patients to find a donor through family and friends, so why not now pay them if they want?"

One woman who has an over-view of the debate is Lesley Logan, Scottish regional manager of donor care and co-ordination for UK Transplant. Her remit is to oversee the 14 donor co-ordinators working throughout Scotland to match potential donors with recipients across the UK.

Logan highlights a number of critical logistical factors to allow organs to be taken. The deceased must be in an intensive care unit or emergency medical ward at the time of death, and the transplant surgeons based in Edinburgh and Glasgow and ideally one of the national co-ordinators must be geographically accessible. The co-ordinator must assess in a two-hour period of sensitive questioning of the family the potential of the donor through their medical history. This includes probing on everything from HIV or CJD infection, sex with prostitutes or same-sex relationships and asthma or kidney problems, all to ascertain whether organs and tissue can actually be used for transplants.

Having witnessed first hand the distress caused to families as their loved one is taken off to surgery for organ donation, Logan is adamant that the family must be borne in mind. She says: "The first rule of surgery is to do no harm', and unless we get a firm yes or no from a family then presumed consent could ruin families' lives."

However, Logan is sceptical about the investigation requested by Alan Johnson and Nicola Sturgeon into "soft" presumed consent in any case.

If the family of a deceased person could supercede any "presumption" just as they can presently over-ride the wishes of a donor-card holder, it is hard to see what difference the proposals would make to supplies of usable organs, she says.

Given the complicated and diverse issues raised by the contributors, it seems clear that any public consultation process on organ donation must be as informed as possible.