When it comes to organ transplants, conventional wisdom was that the donor and recipient must have compatible blood types.But a Denver surgeon is challenging that way of thinking and saving more lives.Larry and Diane Jones knew their son mark was days from dying."We really thought that we were going to lose him," said Larry Jones.At just 35 years old, the avid outdoorsman had chronic liver failure and was at the top of the list for a transplant."Keeping up hope, keeping the prayers going is really difficult. You begin to wonder, 'Is anything going to happen here?'" said Larry Jones.Finally, last week, a liver became available.There was a catch, though, the donor's blood type wasn't compatible with Mark's."Mark is B positive. The liver is an AB," said Larry Jones.Most surgeons would have considered that risk too great, but Dr. Thomas Heffron at Denver's Porter Adventist Hospital isn't most surgeons.One transplant at a time, he's challenging conventional wisdom about crossing blood types in transplants."It's all about getting a liver to someone before they get too sick," said Heffron. "So the whole idea with children or adults is: How can you get a liver to them quicker? Well, if you can use all blood groups, then you have three times as much. Right?"It was Mark Jones' only hope.7NEWS cameras rolled during his rare, cross blood-type liver transplant.A hospital spokeswoman said Heffron is the only surgeon in the region doing the procedure because of what could happen."The risk is that they have an acute reaction, and they clots off all their blood vessels," said Heffron.However, he said, after performing about 50 of the cross blood-type transplants, that's only happened to him once, and the patient survived.He said the liver just seems more able to adapt to different blood types than other organs.Most of his past research has been in pediatrics."My survival is 94 percent, which is the same as my same-blood group survival," he said. "Compare that to 60 percent survival nationwide in pediatric patients."He said the risk is worth it, and he has published his findings to encourage other liver transplant surgeons not to wait for the right blood type until the patient's too sick."I don't do anything different, other than cross blood groups," he said.But for Mark Jones and his family, that made all the difference.He is now recovering in intensive care."Before surgery, his whole face was yellow. His eyes were yellow... I think even his tears were yellow," said Diane Jones. "Now his skin is starting to look more like its normal color.""He's been extremely weak, but he's improving each day," said Larry Jones. "It almost seems like a miracle."Heffron said that in order to qualify for a cross blood-type transplant in Colorado, the patient's liver has to be extremely sick, or the patient must have status one acute liver failure.Some doctors are trying cross blood-type transplants with kidneys, as well, he said.