More than 500 people will have operations or procedures deferred this week, due to ongoing industrial action by medical imaging technologists.
Those deferments are likely to have a significant effect on waiting lists, the Southern District Health Board said.
The technologists, who operate X-ray machines and other scanning devices, have staged a series of 24-hour stop-works in recent months, but this time are holding a week long series of stoppages.
SDHB chief executive Chris Fleming said more patients had had to have procedures postponed so clinicians could keep more planned appointment times available for acute patient examinations.
"Around 500 X-ray patient appointments will be affected,'' he said.
"Some patients had their appointment brought forward, others have been scheduled at a later date and some appointments were not booked at the time they would have been.''
The CT scan service had held off booking 45-50 patients, around 50 people had had MRI scans either postponed or rescheduled, while an estimated 15 patients would have their nuclear medicine procedures affected.
During industrial action staff are required to be available to provide life-preserving services; that had not been an issue so far and services would be maintained for emergencies, Mr Fleming said.
The technologists are striking nation-wide over safe staffing levels, professional development and recognition of responsibility.
They will stage partial stop-works today, Thursday and next Monday, with 24-hour strikes scheduled for tomorrow and Friday.
"It is difficult to estimate the impact for radiology patients as urgent patients will take priority and be seen at the private providers or replace a non-urgent patient,'' Mr Fleming said.
"We estimate that the impact will be reasonably significant longer term, as patients rescheduled following industrial action will fill appointments that would normally be utilised by more recently referred patients.
"This will continue to have a flow-on effect until we are able to provide the required number of examinations.''
As things stood, 59.2% of patients referred for CT scans at Dunedin Hospital received their examination and had it reported within six weeks of their referral, as did 52.6% of patients referred for MRI.
That was likely to deteriorate, Mr Fleming said.
The strike will affect all services provided by technologists at Dunedin Hospital, Southland Hospital, Lakes District Hospital and community based health services, including Dunedin Urgent Doctors.
Affected patients are being contacted by the SDHB.
