Health officials in Wales have outlined which services will be most affected by upcoming nurse strikes.
Nurses in all but one Welsh NHS employer voted to strike over pay and working conditions for the first time in the Royal College of Nursing's 106-year history.
Industrial action is also taking place across England and Northern Ireland.
The first strike action will take place on Thursday 15 December, with another walkout planned for Tuesday 20 December.
The RCN has said strikes could continue until early May 2023 if a new pay offer is not agreed.
Health boards and Welsh Government officials have been making contingency plans to minimise disruption, with certain services completely protected from strike action.
The services that will be protected across Wales are chemotherapy, dialysis, paediatric emergency departments, paediatric intensive care, neonatal and critical care units.
Adult emergency departments will also see full staffing levels, with emergency nurse practitioners with additional skills also being drafted in to help with things like minor injuries.
Everything else is still being negotiated on a local level between health boards and RCN members, which means services could be affected differently depending on where you live.
Some departments and wards will remain open with reduced staffing levels, similar to Christmas Day.
It also means not all patients have been told whether their treatment will be affected yet, and some could find out at the last minute.
But health boards have said they are aiming to give patients whose treatment is being postponed at least a week's notice.
They added that anyone who has been on a waiting list will not be moved to the bottom of list and will be offered a rescheduled appointment as soon as possible.
Hospitals are also looking at introducing extra capacity to cope with the impact strikes will have on the existing treatment backlog.
Those with planned non-urgent surgeries, such as patients needing a hernia operation, will most likely see their treatment postponed.
Routine, non-urgent orthopaedic patients should also expect treatment cancellations, and services like outpatient clinics are likely to be severely reduced.
The Welsh Government is set to urge the public to still seek emergency care if they need it, but it will encourage those with non-urgent healthcare needs to use 111 and digital services.
The action follows the Welsh Government's announcement of a pay award of £1,400 for all NHS pay bands, the equivalent of 4%.
Discussions between the Welsh Government and the RCN are ongoing, but the Welsh Government is not expected to make a new pay offer unless the UK Government decides to do so in England, which would result in Wales receiving additional funding.
But opposition parties have argued that the Welsh Government does have the powers to give nurses a bigger pay rise.
Nurses' pay is set by governments based on recommendations from an independent pay review body.
The RCN said that despite this year's pay award, experienced nurses are worse off by 20% in real terms due to successive below-inflation awards since 2010.
The RCN is calling for a pay rise of 5% above RPI inflation, saying the economic argument for paying nursing staff fairly is clear when billions of pounds is being spent on agency staff to plug workforce gaps.
The UK Government has said it does not want make any decisions that could lock in current inflation rates.