The report, released yesterday, highlighted a list of failures - from "inter-service warfare" and dysfunction to short-staffing, disparities in treatment and process gaps - that contributed to delayed colonoscopies and the diagnosis and treatment of bowel cancer.
The problems had contributed to adverse outcomes for some patients and the frustrations associated with that had left some Southland staff, in particular, stressed and close to tears, the report found.
It was prepared by two Christchurch auditors, general surgeon Phil Bagshaw and gastroenterologist Steven Ding, and released yesterday, months after a leaked draft was made public by the Otago Daily Times in May.
The report noted the Southern DHB population had, in recent years, one of the highest incidences of colorectal cancer in the country, one of the highest rates of the cancer's spread beyond the bowel and one of the highest rates of emergency surgery in response, coupled with one of the lowest rates of colonoscopy.
The external review looked at 20 cases from recent years.
It found delays in diagnosis in 10 of them, albeit during a period when "many thousands" of colonoscopies were performed.
That included the case of a 71-year-old Southland woman, presenting with rectal bleeding, whose diagnosis and eventual treatment was delayed by three and a-half years.
She had been on a waiting list for a colonoscopy in May 2011 and when the list was reviewed, had indicated she wanted to remain on it. Instead, her name was removed in March 2013, on the assumption she had been waiting so long that "sinister pathology" was unlikely.
The woman later presented again with rectal bleeding, diarrhoea and abdominal pain in October 2014, and a rectal tumour was found.
The auditors concluded the woman should not have been removed from the waiting list without a further clinical evaluation.
The review highlighted delays in nine other cases that led to diagnosis and treatment delays of three and 10 months.
At the same time, raw data showed a gradual decrease in the number of referrals for elective colonoscopies between 2013-14 and 2017-18, which was a concern.
SDHB chief medical officer Dr Nigel Millar, in a statement yesterday, said the report raised "important issues that need to be better understood" but change was already happening.
The SDHB had already moved to align its processes for accessing colonoscopies at Dunedin and Southland Hospitals, he said.
It would also undertake a further review and invest in "building stronger internal relationships" to improve the handling of cases in which endoscopies were requested but standard criteria were not met.
The further review would look at 102 cases where questions had been raised around patients' care pathways.
Dr Millar said any case of delayed care needed to be taken "seriously", but bowel symptoms were for many people not the result of tumours.
It was "impractical" to investigate everyone with symptoms, so additional risk factors were applied to narrow the field.
"Unfortunately, there is always a possibility this misses some cases in people who are referred, but not accepted, for publicly funded colonoscopy.
"However, widening access to colonoscopy, to investigate symptoms that have been shown to be less likely to be due to gastrointestinal tumours, has the unintended consequence of developing longer waiting lists, and delaying access to those patients with symptoms shown to be more likely to be associated with a cancer diagnosis.
"This is a challenging balance to strike."
He said the SDHB had participation rates among the highest in the country, particularly for Maori, and the programme had so far detected 80 cancers that would not otherwise have been detected, and polyps in more than 700 patients.
Health minister David Clark said he had not seen the report and would wait for advice from the Ministry of Health before commenting.
