His formal finding on the death of Claire Adamson, released yesterday, has been forwarded to the Southern District Health Board and Medical Council of New Zealand.
Mrs Adamson, a Dunedin seamstress, died at Dunedin Hospital on March 31, 2011, following surgery from which she developed a fatal whole-of-body inflammation (sepsis).
She underwent surgery on March 8 and was readmitted to hospital on March 23 for symptoms suggestive of an anastomotic leak, in which fluids leak from the failed closure of an organ cut in surgery.
On March 27, she underwent further surgery for investigation and repair of the leak, but the operation proved difficult because of her fragile and inflamed bowel, Mr Crerar said.
''Following this surgery, Claire Adamson developed further complications and she died,'' he said.
The cause of death was ''multi organ failure and peritoneal sepsis with a colonic anastomotic leak, on a background of Crohn's disease''.
Mrs Adamson's cousin, Carol Dobbs, a registered nurse, and other family expressed concern about Mrs Adamson's treatment at Dunedin Hospital, which resulted in meetings with, and investigations by, staff.
Professor Magnus Thorn, who had operated on Mrs Adamson, Dunedin Hospital's clinical leader of general surgery Prof John McCall and hospital service manager Helen Williams were involved in dealings with Mrs Adamson's family.
Prof Thorn prepared a report on the case which was forwarded to Dunedin Hospital's chief medical officer.
Prof Francis Frizelle was commissioned to write an independent report.
''Prof Frizelle expressed concern about the operative management undertaken for the anastomotic leak. In his opinion, the operation on March 27 was much more extensive than that which may have been required,'' Mr Crerar said.
His findings included a summary of Prof Frizelle's report, which stated Mrs Adamson's treatment up to the March 27 surgery was reasonable.
But Prof Frizelle said the operation to repair the anastomotic leak ''departed from the usual standard of care''.
''There is a range of choices of what would be acceptable and exactly what is optimum is debatable. However, what was done departed from what we consider to be reasonable in this situation,'' he said.
''Bowel anastomotic leakage is a significant complication with up to one in three patients dying as a direct result ... it is one of the most common and devastating complications of all surgery,'' Prof Frizelle said.
Mr Crerar's findings did not detail why the surgery performed was not acceptable.
He said medical practitioners and surgeons could not be expected to attain a standard of perfection and all surgery carried risk.
''I have no evidence that would indicate Claire Adamson was not advised appropriately of the risks of surgery. Claire Adamson was cruelly debilitated by Crohn's disease and its complications, and was seeking a better lifestyle outcome which it was hoped by her, and by her surgeons, could have been achieved by the operation,'' Mr Crerar said.
He was satisfied Prof Thorn provided appropriate care to Mrs Adamson until deciding to operate on March 27.
''I am required to accept the summary of Prof Frizelle about this, that what was undertaken was not appropriate for the patient's situation,'' Mr Crerar said.
He recommended his finding be used by the SDHB to inform clinicians and for training.
