"That is extremely concerning as you have to wonder, at that point, if the patient has somehow become infected."
The board has had problems before with unsterile instruments.
In 2019, it reported that two patients had been operated on with dirty instruments, including congealed blood inside a surgical screwdriver.
Neither of those people had been told as they had been considered at extremely low risk of infection.
Dr Millar said the latest issues during operations with poor cleaning of equipment, which had happened between March 31 last year and January 31 this year, were also low-risk events.
The instruments had been sterilised, but the problems discovered mid-operation, including water being left inside tubing, instrument trays not being properly cleaned and matter being left on instruments, were unsatisfactory, Dr Millar said.
Nurses had also discovered issues with equipment prior to operations and rejected them.
"The infection risk is vanishingly small, but it is a matter of distress for patients."
Sterile services staff were working in a very difficult area and doing their best in the circumstances, Dr Millar said.
An efficient and properly designed space to work in was essential to address the problem.
The increasing number of problems with dirty instruments or medical equipment prompted the board to start work on a project to relocate sterile services to roomier accommodation in the Oncology building.
Specialist services executive director Patrick Ng told board members they would receive an update on the proposal soon.
Design work had suggested the project would cost more than proposed, but Ng believed there were opportunities to bring that figure down.
Meanwhile, the air pressure issues which have prevented the board from opening the second stage of its $14.8million new critical care ward are no closer to resolution.
Ng said work was continuing with mechanical engineers to get a design to rectify the issue completed, peer-reviewed and signed off for remediation.
In the meantime, the board had written to the architect of the ventilation system to advise that it believed the architect had an obligation to remediate the design.
Ng would not comment further as a meeting was scheduled with the architect for today.
The 10-bed ward was meant to have opened in early 2020, but it could be late 2022 before it can receive patients.