Hannah Jones, who was diagnosed with leukemia and later a heart condition, told her parents and medical authorities that she would rather spend her remaining time at home than in the hospital. Health authorities have ceded to the decision after interviewing the girl.
"I've been in hospital too much - I've had too much trauma," Hannah Jones told Sky News on Tuesday. "I don't want this, and it's my choice not to have it."
Hannah was diagnosed with leukemia when she was 4 years old. Chemotherapy put her into remission but doctors then discovered she had cardiomyopathy, a serious disease where the heart muscle becomes swollen and sometimes fails.
The girl's story surfaced when parents complained about hospital officials who sent a social worker to interview the girl about her choice.
The family received a telephone call saying the hospital would take legal action if they didn't bring Hannah to hospital, said her mother, Kirsty Jones.
"They phoned us on a Friday evening and said that if we didn't take her in they'd come and take her. We still refused to take her," she said.
Hospital officials said it is standard procedure to make sure both the child and their parents understand the consequences of any medical decision.
"Clearly, the welfare of the child is paramount," said Sally Stucke, a pediatrician with the Herefordshire Primary Care Trust where Hannah was receiving treatment. "Pediatricians will always consider the child's best interests at all times and this would include the child's medical, emotional and psychological well-being."
"No one can be forced to have a heart transplant," she added.
Dr. Tony Calland, who chairs the British Medical Association's medical ethics committee, told BBC radio that a 13-year-old like Hannah, supported by her parents, should be "perfectly capable" of making such a decision.
"Decisions to refuse life-prolonging treatment are always extremely difficult and emotive," he said. "What is paramount is that decisions are made in the best interests of the patient. Where consensus cannot be reached between doctors, patients and family, then it is only appropriate that the courts intervene to act in the best interests of the patient."
Dr. John Jenkins, a pediatrician and chairman of Britain's General Medical Council standards and ethics committee, said children who have lengthy illnesses become "experts in their own condition quite early in life."
Heart transplants are risky operations on any patient - and those risks increase with young people who have additional conditions like Hannah's leukemia.
The transplants often require patients to be on lifelong anti-rejection medication to prevent their body from attacking their new heart. The medicines often have side-effects, which make the body more susceptible to dangerous infections.
"I just decided there were too many risks, and even if I took it there might be a bad outcome," Hannah said. "There is a chance that I may be OK, and there's a chance that I may not be as well as I could be, but I'm willing to take that chance."