About 100 patients in South Australia were given false positive results for prostate cancer in a bungle that has now led to the sacking of a key health executive.

Key points: Urologist questions if errors extend back to test manufacturer Siemens

Urologist questions if errors extend back to test manufacturer Siemens Minister Jack Snelling wants to know how SA Health dealt with the patients involved

Minister Jack Snelling wants to know how SA Health dealt with the patients involved SA Opposition says it is yet another health system issue which undermines confidence

Health Minister Jack Snelling demanded an independent inquiry when he found out from the media about the blunder.

The errors in test results since January from SA Pathology were picked up when Adelaide urologist Peter Sutherland ordered fresh testing for some of his patients when they returned concerning results despite already having had their prostate glands removed.

Dr Sutherland, the senior visiting urologist at the Royal Adelaide Hospital, said he had as many as 40 patients affected by the mistake and thinks dozens more also got incorrect results.

"Thankfully we repeated the test with other labs and showed it wasn't correct," he said.

"[Some patients were] quite distressed and worried about it so there was some real human misery associated with this in some men who were seriously worried they had recurrent cancer."

At a news conference in Adelaide on Sunday, health officials announced SA Pathology executive director Ken Barr had been sacked and confirmed there would be an independent investigation, as the Minister had demanded.

Central Adelaide local health network chief executive Julia Squire said the public should continue to have confidence in SA Pathology's services.

"Sometimes things don't always work to plan in health services, we know that, but it's really important that people feel confident when things don't go right that they know about it and that those issues are identified and we deal with it appropriately," she said.

Mr Snelling said he was furious about his department SA Health's handling of the matter.

"I don't have an enormous amount of confidence in what I've been told until such time as there is an independent investigator comes in and properly briefs me on what's happened," he said.

"This is the sort of thing that should be being communicated up to me and I'm extraordinarily frustrated that it wasn't.

"I'm determined to get to the bottom of it. It does worry me though that there are some people in SA Health who don't seem to think that they're answerable to anybody."

Opposition hits out at SA Pathology statement

Opposition health spokesman Stephen Wade said a statement on SA Pathology's website which mentioned testing improvements revealed nothing about there having been a blunder.

He said patients and the South Australian public deserved better.

"It's important that SA Health tells us what have they done to make sure that all relevant patients have been notified," Mr Wade said.

"It also raises serious questions about whether or not the Health Minister has actually lost control of his own department."

On its website, SA Pathology mentioned testing was reviewed as part of "our continuous quality improvement program".

It said it would run a new testing system in parallel with its old system for at least six months, and give both results to doctors.

Whilst our PSA results have been highly accurate and reliable in the core range, we have moved to improve values below 0.15ug/L, where some patients have required repeat testing. The new method offers a more sensitive PSA assay ... [and] SA Pathology will run previous and current systems in parallel for a minimum of six months. This will allow doctors to compare at least two results measured by the new method in individual patients and ensure continuity of care.

Mr Snelling said SA Pathology's statement was "certainly not what I would call full and frank disclosure".

"But, as I say, when they're not telling the Minister these sorts of things it does concern me that they're not telling the public about it either," he said.

Urologist has 'some sympathy' for SA Pathology

Dr Sutherland said the testing quality was an issue he expected went beyond SA Pathology.

"This is very complex chemistry that's going on here and I do have some sympathy with them because this is a test that they've run for a long time and it's always been reliable — and to suddenly get a change for them was a real surprise," he said.

"Thankfully we were sort of onto the fact that it was inaccurate, so we were rapidly repeating tests.

"So while it did take some weeks for them to get onto this, I can understand why they were reticent to believe it.

"I think this is in fact more a problem with the test, which is made by Siemens, that SA Pathology were using so the problem really relates back to Siemens and why they had a problem with their reagents through Christmas which they were supplying to SA Pathology."

Jack Snelling says he wants to know how authorities dealt with the patients caught up in the bungle. ( ABC News: Kate Hill )

A Siemens spokesmen said the company took the matter seriously and were "fully investigating to ensure we have all the facts to avoid speculation".

"We will continue to work closely with SA Health to support them in any way they need," the spokesperson said.

The Minister expressed concern for the men who had faced misdiagnosis.

"I have spoken to the chief executive of SA Health David Swan and instructed him to appoint an independent investigator to have a look, to find out what happened, how it happened and how it was communicated to the patients as well, which worries me," he said.

Mr Wade said it was another health blunder which undermined the public's faith in Mr Snelling and the Government's handling of the health system.

"He tells us that he won't take for granted anything that he's been told until he's had an independent investigation so, given that the Minister can't trust what his department says, how does he expect South Australians to believe what he says about other important breaches, like the 21 patient privacy breaches and the chemotherapy dosing bungle?" the Opposition frontbencher asked.

"They've had a whole series of events in relation to SA Health where serious concerns have been raised, the Minister claims he wasn't informed.

"This is continuing to undermine the public's confidence in the public health system and the Minister's capacity to manage it."