Patients who refuse blood transfusions after severe blood loss have a poor prognosis but survival is possible. Below Simon Finfer and colleagues describe how they managed two patients who presented after a car crash. We asked an ethical expert, a former pathologist who is a Jehovah's Witness, and a lawyer to comment on the issues that these cases raised.

Patients with severe injuries who refuse blood transfusion present complex medical, legal, and moral problems. In many cases treatment may seem futile but occasionally patients will survive despite severe haemodilution. We report the cases of two men who were badly injured when their car was impaled on a motorway crash barrier.