Pathologist Professor Sebastian Lucas performs a 'consented' post mortem.
As he wrestles with the uncertainties surrounding the patient's death, he shows Geoff Watts why he believes this once common practice remains valuable to modern medicine.
The majority of post mortems today are requested by a coroner, when an unnatural cause of death is suspected.
In contrast, 'consented' post mortems are performed when there's uncertainty about a natural death.
They're requested by a doctor with permission from relatives.
Until the 1960s, these post mortems played a crucial role in medical practice.
Professor Lucas remembers performing about a dozen a week to clarify why people died, teach medical staff and students, and improve clinical practice.
But over his career he's witnessed a sharp decline, and today he performs just one a week.
Understanding why people die matters.
Even though developments in scanning and biopsy techniques have improved diagnosis in the living, studies spanning a hundred years show that doctors get the cause of death wrong on the death certificate in up to thirty percent of cases.
Given that mortality statistics affect how resources are allocated within the NHS, Professor Lucas believes crucial public health information is being buried with the dead.
His solution? To boost the number of post mortems on people dying of the diseases upon which most public money is being spent.
Professor Lucas performs a 'consented' post mortem, defending its contribution to medicine.