Mistakes by family doctors and a medical centre meant an elderly woman waited almost four months to find out she had bowel cancer.
The case is revealed in a report released on Monday by the Deputy Health and Disability Commissioner, Theo Baker.
The 81-year-old patient had already had bowel cancer and was at high risk when she visited her unnamed doctor because of tiredness in 2011. She was referred for a colonoscopy examination but opted for a less invasive CT bowel scan privately instead.
The scan revealed a tumour, but the results were sent to a medical centre where the referring doctor used to work, rather than the current one. Both the current medical centre and two unnamed doctors working there failed to follow up on the results to see what they showed.
One, a locum doctor, didn't know how to use his electronic reminder system for results.
Ms Baker says the errors began with mistakes by the first doctor involved.
"He didn't put any reminder to himself to follow up on that and he wasn't aware that it (the colonoscopy) hadn't happened, that she'd actually had a colonography. It really is the role of the referring doctor to follow up on results, and act on them as necessary."
The patient had a successful operation but Ms Baker says the standard of care was unacceptable.