Auckland Hospital does not have enough nurses to have all of its operating theatres running as it tries to catch up after Covid-19 delays.
It was likely to be down at least one theatre a day indefinitely.
The shortage was pouring cold water on the region's attempt to catch up after thousands of people had their surgery deferred at the height of the Omicron outbreak.
RNZ understands the general surgical department at Auckland City Hospital was down almost a quarter of its full theatre nurse capacity.
That meant at least one of its operating theatres could not be used each day - reducing its capacity by a minimum of 10 percent.
When asked about the situation, Auckland District Health Board provided only a combined figure for all departments at both Auckland City and Greenlane hospitals, saying it was 14 percent down on the full contingent of theatre nurses.
During the Omicron outbreak, nearly all surgery at Greenlane Hospital ceased while Auckland Hospital did only emergency procedures and the most urgent planned care such as for cancer operations that could not wait.
That meant more than 1700 patients were added to the already existing backlog.
No one from Auckland DHB would be interviewed on the matter but in a statement it said it was trying to do as many operations as it could.
Sometimes, not having enough available surgeons, anaesthetic technicians, anaesthetists and healthcare assistants also contributed to surgeries not going ahead, a spokesperson said.
And sometimes surgery could not happen because there would not be enough space in the wards to care for patients before or after, she said.
The DHB's director of perioperative services Nigel Robertson said staff illness was also still having an impact but they were operating as many theatres as possible each day.
"We want to assure the public that if you need hospital level care, we are here. We're coordinating with our regional and national DHB counterparts to manage demand and maximise available capacity, to deliver as much planned care as possible," he said.
The problem was not unique to Auckland, but other DHBs told RNZ they could not immediately say how big their theatre nurse shortage were.
They instead put the request through their, often lengthy, Official Information Act request process.
Christchurch Hospital had to suddenly put off surgery this week as a surge in illness in the community and among staff meant the hospital had more patients than beds.
Health NZ, which would replace the country's DHBs from next month, set up a taskforce to try to tackle nationwide delays.
At the announcement last month, the Minister of Health Andrew Little said there were 27,000 people who had been waiting longer than four months for surgery, compared with 8000 in March 2019.
Nurses' Organisation president Anne Daniels said getting more nurses was critical to overcoming the delays and she was disappointed there was no union representative on the task force.
Theatre nurses were highly skilled and specialised and there needed to be a pathway to making sure more were trained in New Zealand, as well as brining in more from overseas, she said.
In the meantime, those working in the system were mentally and physically fed up as they kept working despite the shortages.
"It is just heartbreaking for them to go to work knowing they're not going to be able to do the best job that they can, that they're not going to be able to give the best level of care they can," she said.