A seven-month-old Jehovah's Witness has had a liver transplant in one of the first bloodless surgeries on an infant.
Doctors now intend to make the procedure routine to reduce blood shortages.
The boy, who was given a piece of his grandmother's liver, can't have blood transfusions because of his parents' beliefs.
Usually the transplant surgery uses two to three units of donated blood. Instead, doctors used drugs to stimulate red blood cell production and recycled the blood from his own incisions.
It was so successful they will now do the same even on patients who do not hold those religious beliefs.
Dr Yuri Genyk, who helped carry out the operation at Children's Hospital Los Angeles, said: "We made special arrangements in this case because of this family's religious beliefs, but from now on we'll do this on every child to reduce our use of blood products."
The bloodless liver procedure has been performed on four adult Jehovah's Witnesses at UCS University Hospital.
Twenty more people - not necessarily Jehovah's Witnesses - are being evaluated to undergo the procedure.